fuel type BMW 3 SERIES 1985 E30 User Guide

cover, remove the vibration damper/hub by
locking the crankshaft in position and
loosening the large centre bolt. Since the bolt
is on very tight, you’ll need to use an
extension bar and socket to break it loose. On
M30 engines, BMW recommends using a
3/4-inch drive socket and extension bar, since
the bolt is extremely tight on these engines.
To lock the crankshaft in place while the bolt
is being loosened, use BMW special tool
No. 11 2 100 (or equivalent).
9On the M10 engine, if the special tool listed
in the previous paragraph is not available, you
may try locking the crankshaft by removing
the flywheel/driveplate inspection cover and
jamming a wide-bladed screwdriver into the
ring gear teeth. On the M30 engine, since the
bolt is so extremely tight, we don’t
recommend substitute methods. Use the
correct tool. On the M10 engine, after the
centre bolt is removed, it will probably be
necessary to use a jaw-type puller to pull the
vibration damper off the crankshaft. Position
the jaws behind the inner pulley groove, and
tighten the puller centre bolt very slowly,
checking the pulley to make sure it does not
get bent or otherwise damaged by the puller.
10Unscrew the plug and remove the timing
chain tensioner spring (see illustration). The
tensioner plunger may come out with the
spring. If not, reach down into the hole where
the tensioner spring was, and remove the
plunger. To check the plunger for proper
operation, see Section 8.
Caution: The spring is under
tension, and this could cause the
plug to be ejected from its hole with
considerable force. Hold the
tensioner plug securely as it’s beingunscrewed, and release the spring tension
slowly.
11On the M30 engine, if you’re removing the
upper timing cover, unbolt the thermostat cover
and remove the thermostat (see Chapter 3).
12On the M30 engine, if you’re removing the
lower timing cover, loosen the alternator
mounting bolts, and swing the alternator to
one side. Remove the front lower mounting
bracket bolt, and loosen the other bolts. Also
unbolt the power steering pump mounting
bracket, and move it to one side.
13Remove the bolts and nuts securing the
upper timing chain cover to the engine block,
and remove the cover. Draw a simple diagram
showing the location of the bolts, so they can
be returned to the same holes from which
they’re removed. Remove the upper timing
chain cover. If it sticks to the engine block, tap
it gently with a rubber mallet, or place a piece
of wood against the cover and hit the wood
with a hammer. On the M30 engine fitted with
the L-Jetronic fuel system, remove the
distributor driveshaft.
14Remove the bolts and nuts attaching the
lower timing chain cover to the engine block.
Be sure to remove the three bolts from
underneath that connect the front of the sump
to the bottom of the front cover (see
illustration). Loosen the remaining sump bolts.
15Run a sharp, thin knife between the sump
gasket and lower timing chain cover, cutting
the cover free from the gasket. Be very careful
not to damage or dirty the gasket, so you can
re-use it.
16Break the lower timing chain cover-to-
block gasket seal by tapping the cover with a
rubber mallet, or with a hammer and block of
wood. Do not prise between the cover and the
engine block, as damage to the gasket sealing
surfaces will result.
17Using a scraper, remove all traces of old
gasket material from the sealing surfaces of
the covers and engine block.
Caution: Be very careful not to
scratch or gouge the delicate
aluminium surfaces. Also, do not
damage the sump gasket, and
keep it clean. Gasket removal solvents are
available at motor factors, and may prove
helpful. After all gasket material has beenremoved, the gasket surfaces can be
degreased by wiping them with a rag
dampened with a suitable solvent.Refitting
18Renew the front oil seals (see Section 11).
It’s not wise to take a chance on an old seal,
since renewal with the covers removed is very
easy. Be sure to apply a little oil to the front oil
seal lips.
19Apply a film of RTV-type gasket sealant to
the surface of the sump gasket that mates
with the lower timing chain cover. Apply extra
beads of RTV sealant to the edges where the
gasket meets the engine block. Note:If the
sump gasket is damaged, instead of fitting a
whole new gasket, you might try trimming the
front portion of the gasket off at the point
where it meets the engine block, then trim off
the front portion of a new sump gasket so it’s
exactly the same size. Cover the exposed
inside area of the sump with a rag, then clean
all traces of old gasket material off the area
where the gasket was removed. Attach the
new gasket piece to the sump with contact-
cement-type gasket adhesive, then apply
RTV-type sealant as described at the
beginning of this paragraph.
20Coat both sides of the new gasket with
RTV-type gasket sealant, then attach the
lower timing chain cover to the front of the
engine. Refit the bolts, and tighten them
evenly to the torque listed in this Chapter’s
Specifications. Work from bolt-to-bolt in a
criss-cross pattern to be sure they’re
tightened evenly.Note 1:Tighten the lower
cover-to-block bolts first, then tighten the
sump-to-cover bolts. If the gasket protrudes
above the cover-to-block joint, or bunches up
at the cover-to-sump joint, trim the gasket so
it fits correctly.Note 2:After applying RTV-
type sealant, reassembly must be completed
in about 10 minutes so the RTV won’t
prematurely harden.
21Refit the upper timing chain cover in the
same way as the lower cover. If the gasket
protrudes beyond the top of the cover and the
engine block, trim off the excess with a razor
blade.
22Refitting is otherwise the reverse of
removal.
In-car engine repair procedures 2A•7
7.14 From underneath the vehicle, remove
the three bolts (arrowed) that connect the
cover and the sump7.10 Unscrew the plug from the timing
chain cover, and remove the tensioner
spring and plunger7.7 Place a socket and ratchet on the
centre bolt to keep the pulley stationary,
and use another socket and ratchet to
remove the smaller bolts attaching the
pulley to the vibration damper
2A
If the pulley seems to be
sticking on the crankshaft, it
may help to spray the hub
area with some penetrating
oil, and to gently tap on the hub area
with a hammer.

22Using a scraper, remove all traces of old
gasket material from the sealing surfaces of
the covers and engine block.
Caution: Be very careful not to
scratch or gouge the delicate
aluminium surfaces. Also, do not
damage the sump gasket, and
keep it clean. Gasket removal solvents are
available at motor factors, and may
prove helpful. After all gasket material has
been removed, the gasket surfaces
can be degreased by wiping them
with a rag dampened with a suitable
solvent.
23Support the cover on two blocks of wood,
and drive out the seals from behind with a
hammer and screwdriver. Be very careful not
to damage the seal bores in the process.
24Coat the outside diameters and lips of the
new seals with multi-purpose grease, and
drive the seals into the cover with a hammer
and a socket slightly smaller in diameter than
the outside diameter of the seal.
25Apply a film of RTV-type gasket sealant to
the surface of the sump gasket that mates
with the front cover. Apply extra beads of RTV
sealant to the edges where the gasket meets
the engine block. Note:If the sump gasket is
damaged, instead of fitting a whole new
gasket, you might try trimming the front
portion of the gasket off at the point where it
meets the engine block, then trim off the front
portion of a new sump gasket so it’s exactly
the same size. Cover the exposed inside area
of the sump with a rag, then clean all traces of
old gasket material off the area where the
gasket was removed. Attach the new gasket
piece to the sump with contact-cement-type
gasket adhesive, then apply RTV-type sealant
as described at the beginning of this
paragraph.
26Coat both sides of the new gasket with
RTV-type gasket sealant, then attach the front
cover to the front of the engine, carefully
working the seals over the crankshaft and
intermediate shaft. Refit the bolts and tighten
them evenly to the torque listed in this
Chapter’s Specifications. Work from bolt-to-
bolt in a criss-cross pattern, to be sure they’re
tightened evenly.Note 1:Tighten the front
cover-to-block bolts first, then tighten the
sump-to-cover bolts. Note 2:After applying
RTV-type sealant, reassembly must be
completed in about 10 minutes so the RTV
won’t prematurely harden.
27The remainder of refitting is the reverse of
removal.
Crankshaft front seal (M40 engines)
28Remove the timing belt and crankshaft
sprocket (see Section 10).
29Remove the Woodruff key from the
groove in the end of the crankshaft.
30Note the fitted position of the oil seal, then
prise it out from the front cover using a
screwdriver, but take care not to damage the
bore of the cover or the surface of thecrankshaft. If the seal is tight, drill two small
holes in the metal end of the seal, and use two
self-tapping screws to pull out the seal. Make
sure all remains of swarf are removed.
31Coat the outside diameter and lip of the
new seal with multi-purpose grease, then
drive it into the cover with a hammer and a
socket slightly smaller in diameter than the
outside diameter of the seal. Make sure the
seal enters squarely.
32The remainder of refitting is the reverse of
removal. Note that it is recommended that the
timing belt be renewed - see Section 10.
12 Cylinder head-
removal and refitting
5
Removal
1Relieve the fuel pressure on all fuel injection
engines (see Chapter 4).
2Disconnect the negative cable from the
battery. Where the battery is located in the
engine compartment, the battery may be
removed completely (see Chapter 5).
Caution: If the radio in your
vehicle is equipped with an anti-
theft system, make sure you
have the correct activation code
before disconnecting the battery.
Note: If, after connecting the battery, the
wrong language appears on the instrument
panel display, refer to page 0-7 for the
language resetting procedure.
3Remove the air cleaner assembly (see
Chapter 4).
4Disconnect the wiring from the distributor
(mark all wiring for position first, if necessary),
and the HT lead from the coil (see Chapter 5).
5Disconnect the lead from the coolant
temperature sender unit (see Chapter 3).
6Disconnect the fuel lines from the fuel rail or
carburettor as applicable (see Chapter 4).
7Drain the cooling system (see Chapter 3).
8Clearly label then disconnect all other
hoses from the throttle body, intake manifold,
carburettor and cylinder head, as applicable.
9Disconnect the throttle cable from the
throttle linkage or carburettor (see Chapter 4).
10Disconnect the exhaust manifold from the
cylinder head (see Section 6). Depending on
the engine type, It may not be necessary to
disconnect the manifold from the exhaust
pipe; however, on right-hand-drive models,
the steering column intermediate shaft may
not allow the manifold to clear the studs on
the cylinder head.
11Remove or disconnect any remaining
hoses or lines from the intake manifold,
including the ignition advance vacuum line(s),
and the coolant and heater hoses.
12On early carburettor models, disconnect
the wiring from the alternator and starter
motor.13Remove the intake manifold (see Sec-
tion 5). Do not dismantle or remove any fuel
injection system components unless it is
absolutely necessary.
14Remove the fan drivebelt and fan (see
Chapter 3).
15Remove the valve cover and gasket (see
Section 4). Remove the semi-circular rubber
seal from the front of the cylinder head, where
this is not incorporated in the valve cover
gasket.
16Set No 1 piston at Top Dead Centre on
the compression stroke (see Section 3).
17Remove the timing chain or belt (see
Section 8 or 10). Note:If you want to save
time by not removing and refitting the timing
belt or chain and re-timing the engine, you can
unfasten the camshaft sprocket and suspend
it out of the way - with the belt or chain still
attached - by a piece of rope. Be sure the
rope keeps firm tension on the belt or chain,
so it won’t become disengaged from any of
the sprockets.
18Loosen the cylinder head bolts a quarter-
turn at a time each, in the reverse of the
tightening sequence shown (see illustrations
12.30a, 12.30b, 12.30c or 12.30d). Do
notdismantle or remove the rocker arm
assembly at this time on M10, M20 and M30
engines.
19Remove the cylinder head by lifting it
straight up and off the engine block. Do not
prise between the cylinder head and the
engine block, as damage to the gasket sealing
surfaces may result. Instead, use a blunt bar
positioned in an intake port to gently prise the
head loose.
20Remove any remaining external
components from the head to allow for
thorough cleaning and inspection. See
Chapter 2B for cylinder head servicing
procedures. On the M40 engine, remove the
rubber O-ring from the groove in the top of the
oil pump/front end cover housing.
Refitting
21The mating surfaces of the cylinder head
and block must be perfectly clean when the
head is refitted.
22Use a gasket scraper to remove all traces
of carbon and old gasket material, then clean
the mating surfaces with a suitable solvent. If
there’s oil on the mating surfaces when the
head is refitted, the gasket may not seal
correctly, and leaks could develop. When
working on the block, stuff the cylinders with
clean rags to keep out debris. Use a vacuum
cleaner to remove material that falls into the
cylinders.
23Check the block and head mating
surfaces for nicks, deep scratches and other
damage. If the damage is slight, it can be
removed with a file; if it’s excessive,
machining may be the only alternative.
24Use a tap of the correct size to chase the
threads in the head bolt holes, then clean the
holes with compressed air - make sure that
In-car engine repair procedures 2A•13
2A

otherwise a small brush or even a bicycle tyre
pump will work). The idea is to prevent dirt
from getting into the cylinders as the
compression check is being done.
3Remove all the spark plugs from the engine
(see Chapter 1).
4Block the throttle wide open, or have an
assistant hold the throttle pedal down.
5On carburettor models, disconnect the LT
lead from the coil. On fuel injection models,
disable the fuel pump and ignition circuit by
removing the main relay(see illustration).
This is to avoid the possibility of a fire from
fuel being sprayed in the engine
compartment. The location of the main relay is
generally near the fuse panel area under the
bonnet, but refer to Chapter 12 for the
specific location on your model.
6Fit the compression gauge in the No 1
spark plug hole (No 1 cylinder is nearest the
radiator).
7Turn the engine on the starter motor over at
least seven compression strokes, and watch
the gauge. The compression should build up
quickly in a healthy engine. Low compression
on the first stroke, followed by gradually-
increasing pressure on successive strokes,
indicates worn piston rings. A low
compression reading on the first stroke, which
doesn’t build up during successive strokes,
indicates leaking valves or a blown head
gasket (a cracked head could also be the
cause). Deposits on the undersides of the
valve heads can also cause low compression.
Record the highest gauge reading obtained.
8Repeat the procedure for the remaining
cylinders, and compare the results to the
compression listed in this Chapter’s Specifi-
cations.
9If compression was low, add some engine
oil (about three squirts from a plunger-type oil
can) to each cylinder, through the spark plug
hole, and repeat the test.
10If the compression increases after the oil
is added, the piston rings are definitely worn.
If the compression doesn’t increasesignificantly, the leakage is occurring at the
valves or head gasket. Leakage past the
valves may be caused by burned valve seats
and/or faces or warped, cracked or bent
valves.
11If two adjacent cylinders have equally low
compression, there’s a strong possibility that
the head gasket between them is blown. The
appearance of coolant in the combustion
chambers or the crankcase would verify this
condition.
12If one cylinder is 20 percent lower than the
others, and the engine has a slightly rough
idle, a worn exhaust lobe on the camshaft
could be the cause.
13If the compression is unusually high, the
combustion chambers are probably coated
with carbon deposits. If that’s the case, the
cylinder head should be removed and
decarbonised.
14If compression is way down, or varies
greatly between cylinders, it would be a good
idea to have a leak-down test performed by a
garage. This test will pinpoint exactly
where the leakage is occurring and how
severe it is.
4 Engine removal-
methods and precautions
If you’ve decided that an engine must be
removed for overhaul or major repair work,
several preliminary steps should be taken.
Locating a suitable place to work is
extremely important. Adequate work space,
along with storage space for the vehicle, will
be needed. If a workshop or garage isn’t
available, at the very least a flat, level, clean
work surface made of concrete or asphalt is
required.
Cleaning the engine compartment and
engine before beginning the removal
procedure will help keep tools clean and
organised.
An engine hoist or A-frame will also be
necessary. Make sure the equipment is rated
in excess of the combined weight of the
engine and accessories. Safety is of primary
importance, considering the potential hazards
involved in lifting the engine out of the vehicle.
If the engine is being removed by a novice,
a helper should be available. Advice and aid
from someone more experienced would also
be helpful. There are many instances when
one person cannot simultaneously perform all
of the operations required when lifting the
engine out of the vehicle.
Plan the operation ahead of time. Arrange
for or obtain all the tools and equipment you’ll
need prior to beginning the job. Some of the
equipment necessary to perform engine
removal and refitting safely and with relative
ease are (in addition to an engine hoist) a
heavy-duty trolley jack, complete sets of
spanners and sockets as described in thefront of this manual, wooden blocks, and
plenty of rags and cleaning solvent for
mopping up spilled oil, coolant and fuel. If the
hoist must be hired, make sure that you
arrange for it in advance, and perform all of
the operations possible without it beforehand.
This will save you money and time.
Plan for the vehicle to be out of use for
quite a while. A machine shop will be required
to perform some of the work which the do-it-
yourselfer can’t accomplish without special
equipment. These establishments often have
a busy schedule, so it would be a good idea
to consult them before removing the engine,
in order to accurately estimate the amount of
time required to rebuild or repair components
that may need work.
Always be extremely careful when removing
and refitting the engine. Serious injury can
result from careless actions. Plan ahead, take
your time and a job of this nature, although
major, can be accomplished successfully.
Warning: The air conditioning
system is under high pressure.
Do not loosen any fittings or
remove any components until
after the system has been discharged by a
qualified engineer. Always wear eye
protection when disconnecting air
conditioning system fittings.
Caution: If removing the M40
engine, it is important not to turn
the engine upside-down for
longer than 10 minutes since it is
possible for the oil to drain out of the
hydraulic tappets. This would render the
tappets unserviceable, and damage could
possibly occur to the engine when it is
next started up.
5 Engine- removal and refitting
3
Caution: If the radio in your
vehicle is equipped with an anti-
theft system, make sure you
have the correct activation code before
disconnecting the battery.
Note: If, after connecting the battery, the
wrong language appears on the instrument
panel display, refer to page 0-7 for the
language resetting procedure.
Removal1Relieve the fuel system pressure (see
Chapter 4), then disconnect the negative
cable from the battery.
2Cover the wings and front panel, and
remove the bonnet (see Chapter 11). Special
pads are available to protect the wings, but an
old bedspread or blanket will also work.
3Remove the air cleaner housing and intake
ducts (see Chapter 4).
4Drain the cooling system (see Chapter 1).
5Label the vacuum lines, emissions system
hoses, wiring connectors, earth straps and
fuel lines, to ensure correct refitting, then
General engine overhaul procedures 2B•5
3.5 As a safety precaution, before
performing a compression check, remove
the cover and the main relay (arrowed)
from the left side of the engine
compartment to disable the fuel and
ignition systems (525i model shown, other
models similar)
2B

detach them. Pieces of masking tape with
numbers or letters written on them work well
(see illustration).
6Label and detach all coolant hoses from the
engine (see Chapter 3).
7Remove the cooling fan, shroud and
radiator (see Chapter 3). Note:On the M40
engine, it is only necessary to remove the
cooling fan and shroud; however, prevent
damage to the radiator by covering it with a
piece of wood or cardboard.
8Remove the drivebelts (see Chapter 1).
9Disconnect the fuel lines from the fuel rail
(see Chapter 4).
Warning: Fuel is extremely
flammable, so take extra
precautions when you work on
any part of the fuel system. Don’t
smoke, or allow open flames or bare light
bulbs, near the work area, and don’t work
in a garage where a natural gas-type
appliance (such as a water heater or
clothes dryer) with a pilot light is present.
If you spill any fuel on your skin, rinse it off
immediately with soap and water. When
you perform any kind of work on the fuel
system, wear safety glasses, and have a
fire extinguisher on hand.
10Disconnect the accelerator cable (see
Chapter 4) and kickdown linkage/speed
control cable (see Chapter 7B), if applicable,
from the engine.
11Where fitted, unbolt the power steering
pump (see Chapter 10). Leave the lines/hoses
attached, and make sure the pump is kept in
an upright position in the engine compartment
(use wire or rope to restrain it out of the way).
12On air-conditioned models, unbolt the
compressor (see Chapter 3) and set it aside,
or tie it up out of the way. Do not disconnect
the hoses.
13Drain the engine oil (see Chapter 1) and
remove the filter. Remove the engine splash
guard from under the engine.
14Remove the starter motor (see Chapter 5).15Remove the alternator (see Chapter 5).
This is not essential on all models, but it is a
good idea in any case to avoid accidental
damage.
16Unbolt the exhaust system from the
engine (see Chapter 4).
17If you’re working on a vehicle with an
automatic transmission, remove the torque
converter-to-driveplate fasteners (see
Chapter 7B). On the M40 engine, unbolt the
automatic transmission fluid coolant pipes
from the sump.
18Support the transmission with a jack.
Position a block of wood between them, to
prevent damage to the transmission. Special
transmission jacks with safety chains are
available - use one if possible.
19Attach an engine sling or a length of chain
to the lifting brackets on the engine. If the
brackets have been removed, the chain can
be bolted directly to the intake manifold studs,
but place a flat washer between the chain and
the nut, and tighten the nut all the way up to
the chain, to avoid the possibility of the studs
bending.
20Roll the hoist into position and connect
the sling to it. Take up the slack in the sling or
chain, but don’t lift the engine.
Warning: DO NOT place any part
of your body under the engine
when it’s supported only by a
hoist or other lifting device.
21On M10, M20 and M30 engines, remove
the transmission rear crossmember, and
slightly lower the rear of the transmission.
22Remove the transmission-to-engine block
bolts using a Torx socket. Note:The bolts
holding the bellhousing to the engine block
will require a swivel at the socket, and a very
long extension going back towards the
transmission.
23Remove the engine mounting-to-frame
bracket nuts. On the M40 engine, unbolt the
dampers from the mountings.
24Recheck to be sure nothing is still
connecting the engine to the transmission or
vehicle. Disconnect anything still remaining.
25Raise the engine slightly. Carefully work it
forwards to separate it from the transmission.
If you’re working on a vehicle with an
automatic transmission, you may find the
torque converter comes forward with theengine. If it stays with the transmission, leave
it, but you may find it easier to let it come
forward until it can be grasped easier and be
pulled from the crankshaft. Note:When
refitting the torque converter to the
transmission before the engine is refitted, be
sure to renew the transmission front pump
seal, which will probably be damaged when
the converter comes out with the engine.
Either method is acceptable, but be prepared
for some fluid to leak from the torque
converter if it comes out of the transmission. If
you’re working on a vehicle with a manual
transmission, draw the engine forwards until
the input shaft is completely disengaged from
the clutch. Slowly raise the engine out of the
engine compartment. Check carefully to make
sure everything is disconnected.
26Remove the flywheel/driveplate (and
where applicable, the engine rear plate), and
mount the engine on an engine stand (see
illustration). Do not turn the M40 engine
upside-down (see Cautionin Section 4).
Refitting
27Check the engine and transmission
mountings. If they’re worn or damaged, renew
them.
28Refit the flywheel or driveplate (see
Chapter 2A). If you’re working on a manual
transmission vehicle, refit the clutch and
pressure plate (see Chapter 7A). Now is a
good time to fit a new clutch.
29If the torque converter came out with the
engine during removal, carefully refit the
converter into the transmission before the
engine is lowered into the vehicle.
30Carefully lower the engine into the engine
compartment - make sure the engine
mountings line up.
31If you’re working on an automatic
transmission vehicle, guide the torque
converter onto the crankshaft following the
procedure outlined in Chapter 7B.
32If you’re working on a manual
transmission vehicle, apply a dab of high-
melting-point grease to the input shaft, and
guide it into the clutch and crankshaft pilot
bearing until the bellhousing is flush with the
engine block.. Do not allow the weight of the
engine to hang on the input shaft.
33Refit the transmission-to-engine bolts,
and tighten them securely.
Caution: DO NOT use the bolts to
force the transmission and
engine together.
34Refit the remaining components in the
reverse order of removal.
35Add coolant, oil, power steering and
transmission fluid as needed.
2B•6 General engine overhaul procedures
5.26 Removing the engine rear plate -
M40 engine5.5 Label each wire before unplugging the
connector
If there’s any possibility of
confusion, make a sketch of
the engine compartment and
clearly label the lines, hoses
and wires.
It may be necessary to rock
the engine slightly, or to turn
the crankshaft, to allow the
input shaft splines to mate
with the clutch plate

36Run the engine and check for leaks and
proper operation of all accessories, then refit
the bonnet and test drive the vehicle.
37Where necessary, have the air
conditioning system recharged and leak-
tested.
6 Engine overhaul- alternatives
The do-it-yourselfer is faced with a number
of options when performing an engine
overhaul. The decision to renew the engine
block, piston/connecting rod assemblies and
crankshaft depends on a number of factors,
with the number one consideration being the
condition of the block. Other considerations
are cost, access to machine shop facilities,
parts availability, time required to complete
the project, and the extent of prior mechanical
experience on the part of the do-it-yourselfer.
Some of the alternatives include:
Individual parts - If the inspection
procedures reveal that the engine block and
most engine components are in re-usable
condition, purchasing individual parts may be
the most economical alternative. The block,
crankshaft and piston/connecting rod
assemblies should all be inspected carefully.
Even if the block shows little wear, the
cylinder bores should be surface-honed.
Crankshaft kit- A crankshaft kit (where
available) consists of a reground crankshaft
with matched undersize new main and
connecting big-end bearings. Sometimes,
reconditioned connecting rods and new
pistons and rings are included with the kit
(such a kit is sometimes called an “engine
kit”). If the block is in good condition, but the
crankshaft journals are scored or worn, a
crankshaft kit and other individual parts may
be the most economical alternative.
Short block- A short block consists of an
engine block with a crankshaft and
piston/connecting rod assemblies already
fitted. New bearings are fitted, and all
clearances will be correct. The existing
camshaft, valve train components, cylinder
head and external parts can be bolted to the
short block with little or no machine shop
work necessary.
Full block - A “full” or “complete” block
consists of a short block plus an oil pump,
sump, cylinder head, valve cover, camshaft
and valve train components, timing sprockets
and chain (or belt) and timing cover. All
components are fitted with new bearings,
seals and gaskets used throughout. The
refitting of manifolds and external parts is all
that’s necessary.
Give careful thought to which alternative is
best for you, and discuss the situation with
local machine shops, parts dealers and
experienced rebuilders before ordering or
purchasing new parts.
7 Engine overhaul-
dismantling sequence
1It’s much easier to dismantle and work on
the engine if it’s mounted on a portable
engine stand. A stand can often be hired quite
cheaply from a tool hire shop. Before the
engine is mounted on a stand, the
flywheel/driveplate should be removed from
the engine.
2If a stand isn’t available, it’s possible to
dismantle the engine with it blocked up on the
floor. Be extra-careful not to tip or drop the
engine when working without a stand.
3If you’re going to obtain a rebuilt engine, all
the external components listed below must
come off first, to be transferred to the new
engine if applicable. This is also the case if
you’re doing a complete engine overhaul
yourself. Note:When removing the external
components from the engine, pay close
attention to details that may be helpful or
important during refitting. Note the fitted
position of gaskets, seals, spacers, pins,
brackets, washers, bolts and other small items.
Alternator and brackets
Emissions control components
Distributor, HT leads and spark plugs
Thermostat and housing cover
Water pump
Fuel injection/carburettor and fuel system
components
Intake and exhaust manifolds
Oil filter and oil pressure sending unit
Engine mounting brackets (see illustration)
Clutch and flywheel/driveplate
Engine rear plate (where applicable)
4If you’re obtaining a short block, which
consists of the engine block, crankshaft,
pistons and connecting rods all assembled,
then the cylinder head, sump and oil pump
will have to be removed as well. See Section 6
for additional information regarding the
different possibilities to be considered.
5If you’re planning a complete overhaul, the
engine must be dismantled and the internal
components removed in the following general
order:
Valve cover
Intake and exhaust manifolds
Timing belt or chain covers
Timing chain/belt
Water pump
Cylinder head
Sump
Oil pump
Piston/connecting rod assemblies
Crankshaft and main bearings
Camshaft
Rocker shafts and rocker arms (M10, M20
and M30 engines)
Cam followers and hydraulic tappets
(M40 engine)
Valve spring retainers and springs
Valves
6Before beginning the dismantling andoverhaul procedures, make sure the following
items are available. Also, refer to Section 21
for a list of tools and materials needed for
engine reassembly.
Common hand tools
Small cardboard boxes or plastic bags for
storing parts
Compartment-type metal box for storing
the hydraulic tappets (M40 engine)
Gasket scraper
Ridge reamer
Vibration damper puller
Micrometers
Telescoping gauges
Dial indicator set
Valve spring compressor
Cylinder surfacing hone
Piston ring groove cleaning tool
Electric drill motor
Tap and die set
Wire brushes
Oil gallery brushes
Cleaning solvent
8 Cylinder head- dismantling
4
1Remove the cylinder head (see Chapter 2A).
2Remove the oil supply tube from its
mounting on top of the cylinder head (see
illustrations). Note:It’s important to renew
the seals under the tube mounting bolts.
General engine overhaul procedures 2B•7
7.3 Engine left-hand mounting bracket -
M40 engine
8.2a Remove the oil tube from the top of
the cylinder head (M10 engine). Be sure to
note the location of all gaskets and
washers for reassembly
2B

information on removing and refitting the
intake manifold, refer to Chapter 2A.
The throttle valve inside the throttle body or
carburettor is actuated by the accelerator
cable. When you depress the accelerator
pedal, the throttle plate opens and airflow
through the intake system increases.
On fuel injection systems, a flap inside the
airflow meter opens wider as the airflow
increases. A throttle position switch attached
to the pivot shaft of the flap detects the angle
of the flap (how much it’s open) and converts
this to a voltage signal, which it sends to the
computer.
Fuel system
On carburettor models, the fuel pump
supplies fuel under pressure to the
carburettor. A needle valve in the float
chamber maintains the fuel at a constant
level. A fuel return system channels excess
fuel back to the fuel tank.
On fuel injection models, an electric fuel
pump supplies fuel under constant pressure
to the fuel rail, which distributes fuel to the
injectors. The electric fuel pump is located
inside the fuel tank on later models, or beside
the fuel tank on early models. Early models
also have a transfer pump located in the fuel
tank. The transfer pump acts as an aid to the
larger main pump for delivering the necessary
pressure. A fuel pressure regulator controls
the pressure in the fuel system. The fuel
system also has a fuel pulsation damper
located near the fuel filter. The damper
reduces the pressure pulsations caused by
fuel pump operation, and the opening and
closing of the injectors. The amount of fuel
injected into the intake ports is precisely
controlled by an Electronic Control Unit (ECU
or computer). Some later 5-Series models
have a fuel cooler in the return line.
Electronic control system (fuel
injection system)
Besides altering the injector opening
duration as described above, the electronic
control unit performs a number of other tasks
related to fuel and emissions control. It
accomplishes these tasks by using data
relayed to it by a wide array of information
sensors located throughout the enginecompartment, comparing this information to
its stored map, and altering engine operation
by controlling a number of different actuators.
Since special equipment is required, most
fault diagnosis and repair of the electronic
control system is beyond the scope of the
home mechanic. Additional information and
testing procedures for the emissions system
components (oxygen sensor, coolant
temperature sensor, EVAP system, etc.) is
contained in Chapter 6.
2 Fuel injection system-
depressurising
1
Warning: Fuel is extremely
flammable, so take extra
precautions when you work on
any part of the fuel system. Don’t
smoke or allow open flames or bare light
bulbs near the work area. Also, don’t work
in a garage where a natural gas-type
appliance with a pilot light is present.
1Remove the fuel pump fuse from the main
fuse panel (see illustrations). Note:Consult
your owner’s handbook for the exact location
of the fuel pump fuse, if the information is not
stamped onto the fusebox cover.
2Start the engine, and wait for it to stall.
Switch off the ignition.
3Remove the fuel filler cap to relieve the fuel
tank pressure.
4The fuel system is now depressurised.
Note:Place a rag around fuel lines before
disconnecting, to prevent any residual fuel
from spilling onto the engine(see
illustration).
5Disconnect the battery negative cable
before working on any part of the system.
Caution: If the radio in your
vehicle is equipped with an anti-
theft system, make sure you
have the correct activation code
before disconnecting the battery. Refer to
the information on page 0-7 at the front of
this manual before detaching the cable.
Note: If, after connecting the battery, the
wrong language appears on the instrument
panel display, refer to page 0-7 for the
language resetting procedure.
3 Fuel pump/fuel pressure-
check
3
Warning: Fuel is extremely
flammable, so take extra
precautions when you work on
any part of the fuel system. Don’t
smoke, or allow open flames or bare light
bulbs, near the work area. Also, don’t work
in a garage where a natural gas-type
appliance with a pilot light is present.
Carburettor engines
1To test the fuel pump, it will be necessary to
connect a suitable pressure gauge between
the fuel pump outlet, and the carburettor
supply pipe. For this particular test, the fuel
return valve, which is normally connected in
the fuel line from the fuel pump to the
carburettor, mustbe bypassed.
2With the engine running at idle speed, the
pump pressure should be between 0.1 and
0.3 bars.
3Should a pressure gauge not be available, a
simpler (but less accurate) method of testing
the fuel pump is as follows.
4Disconnect the outlet hose from the fuel
pump.
5Disconnect the LT lead from the coil, to
prevent the engine firing, then turn the engine
over on the starter. Well-defined spurts of fuel
should be ejected from the outlet hose.
Fuel injection engines
Note 1:The electric fuel pump is located
inside the fuel tank on later models, or beside
the fuel tank on early models. Early models are
also equipped with a transfer pump located in
the fuel tank. The transfer pump feeds the
main pump, but can’t generate the high
pressure required by the system.
Note 2:The fuel pump relay on Motronic
systems is activated by an earth signal from
the Motronic control unit (ECU). The fuel
pump operates for a few seconds when the
ignition is first switched on, and then
continues to operate only when the engine is
actually running.
Fuel and exhaust systems 4•3
2.4 Be sure to place a rag under and
around any fuel line when disconnecting2.1b Removing the fuel pump fuse on
5-Series models2.1a Removing the fuel pump fuse on
3-Series models
4

19Depressurise the fuel system (see Sec-
tion 2).
20Detach the battery negative cable.
Caution: If the radio in your
vehicle is equipped with an anti-
theft system, make sure you
have the correct activation code
before disconnecting the battery. Refer to
the information on page 0-7 at the front of
this manual before detaching the cable.
Note: If, after connecting the battery, the
wrong language appears on the instrument
panel display, refer to page 0-7 for the
language resetting procedure.
21Detach the fuel feed hose from the fuel
rail, and attach a fuel pressure gauge directly
to the hose. Note:If the tee fitting is still
connected to the gauge, be sure to plug the
open end.
22Reconnect the battery.
23Using a jumper wire, bridge the terminals
of the fuel pump relay.
24Turn the ignition switch on to operate the
fuel pump.
25Note the pressure reading on the gauge,
and compare the reading to the fuel pump
pressure listed in this Chapter’s Specifica-
tions.
26If the indicated pressure is less than
specified, inspect the fuel line for leaks
between the pump and gauge. If no leaks are
found, renew the fuel pump.
27Turn the ignition off and wait five minutes.
Note the reading on the gauge, and compare
it to the fuel pump hold pressure listed in this
Chapter’s Specifications. If the hold pressure
is less than specified, check the fuel lines
between the pump and gauge for leaks. If no
leaks are found, renew the fuel pump.
28Remove the jumper wire. Relieve the fuel
pressure by opening the bleed valve on the
gauge and directing the fuel into a suitable
container. Remove the gauge and reconnect
the fuel line.
Transfer pump pressure check
29Depressurise the fuel system (see Sec-
tion 2).
30Detach the battery negative cable.
Caution: If the radio in your
vehicle is equipped with an anti-
theft system, make sure you
have the correct activation code
before disconnecting the battery. Refer to
the information on page 0-7 at the front of
this manual before detaching the cable.
Note: If, after connecting the battery, the
wrong language appears on the instrument
panel display, refer to page 0-7 for the
language resetting procedure.
31Remove the transfer pump access plate
(on some models, it’s located under the rear
seat cushion - on others, it’s located under
the carpet in the luggage compartment).
Disconnect the output hose from the transfer
pump, and connect a fuel pressure gauge to
the outlet pipe.
32Reconnect the battery.33Using a jumper wire, bridge the terminals
of the fuel pump relay.
34Turn the ignition switch on to operate the
fuel pump.
35Note the pressure reading on the gauge,
and compare to the value listed in this
Chapter’s Specifications.
36If the indicated pressure is less than
specified, renew the transfer pump.
Fuel pump relay check
37Switch on the ignition.
38Using a voltmeter, probe the following
terminals from the back of the relay electrical
connector. Check for battery voltage at
terminal 30 (M20 and M30 engines) or
terminal 15 (M10 and M40 engines). Note:If
there is no voltage on models with luggage
compartment-mounted batteries, check for a
faulty fusible link. The 50-amp link is about
6 inches from the battery, in a black wire.
39Turn the ignition off, and disconnect the
relay from the electrical connector. Using a
voltmeter, probe the connector terminals that
correspond to fuel pump relay pins 85 (-) and
86(+) on M20 and M30 engines, or terminal 50
and earth on M10 and M40 engines. Have an
assistant turn the engine over on the starter,
and observe the voltage reading. Battery
voltage should be indicated.
40If there is no voltage, check the fuse(s)
and the wiring circuit for the fuel pump relay. If
the voltage readings are correct, and the fuel
pump only runs with the jumper wire in place,
then renew the relay.
41If the fuel pump still does not run, check
for the proper voltage at the fuel pump
terminals (see Section 4). If necessary, renew
the fuel pump.
4 Fuel pump, transfer pump
and fuel level sender unit-
removal and refitting
2
Warning: Fuel is extremely
flammable, so take extra
precautions when you work on
any part of the fuel system. Don’t
smoke, or allow open flames or bare light
bulbs, near the work area. Also, don’t work
in a garage where a natural gas-type
appliance with a pilot light is present.
Fuel pump (carburettor engines)
1Disconnect the battery negative cable.
Disconnect both hoses from the pump, and
unscrew and remove the two securing nuts
(see illustration).
2Carefully withdraw the pump from the
cylinder head. If it’s stuck, a slight downward
tap on the thick insulating distance piece with
a piece of wood, should free it.
3Remove the two thin gaskets.
4The fuel pump is a sealed unit, and it is not
possible to renew any of the internal
components. Should an internal fault occur, it
must be renewed complete.5Refitting is a reversal of the removal
procedure, but renew the thin gaskets each
side of the insulating distance piece, and
tighten the fuel pump down evenly to the
torque stated in the Specifications. On no
account alter the thickness of the distance
piece, or the correct operation of the fuel
pump will be upset.
Fuel pump (fuel injection
engines)
Note 1: The electric fuel pump is located
inside the fuel tank on later models with the
Motronic system, or adjacent to the fuel tank
on the L-Jetronic system. The early models
are also equipped with a transfer pump
located in the fuel tank. The transfer pump
feeds the larger main pump, which delivers
the high pressure required for proper fuel
system operation.
Note 2: The fuel level sender unit is located in
the fuel tank with the transfer pump on early
models, or with the main fuel pump on later
models.
6Depressurise the fuel system (see Sec-
tion 2) and remove the fuel tank filler cap to
relieve pressure in the tank.
7Disconnect the battery negative cable.
Caution: If the radio in your
vehicle is equipped with an anti-
theft system, make sure you
have the correct activation code
before disconnecting the battery. Refer to
the information on page 0-7 at the front of
this manual before detaching the cable.
Note: If, after connecting the battery, the
wrong language appears on the instrument
panel display, refer to page 0-7 for the
language resetting procedure.
Externally-mounted fuel pump
8Raise and support the vehicle.
9Remove the two rubber boots that protect
the fuel pump connectors, and disconnect the
wires from the pump (see illustration).
10Using hose clamps, pinch shut the fuel
hoses on each side of the fuel pump. If you
don’t have any hose clamps, wrap the hoses
with rags, and clamp them shut with self-
locking pliers, tightened just enough to
prevent fuel from flowing out.
11Disconnect the hoses from the pump.
12Remove the fuel pump mounting screws
Fuel and exhaust systems 4•5
4.1 Fuel pump on carburettor engines
4

correct resistance. On L-Jetronic and early
Motronic systems, follow the table below. On
later Motronic systems, connect the
ohmmeter probes onto the fuel level sender
unit terminals that correspond to pins 1 and 3
on the electrical connector (see illustrations).
The resistance should decrease as the
plunger rises.
L-Jetronic and early Motronic systems
Terminals Float position Resistance
G and 31 Slowly moving Resistance
fromthe EMPTY slowly
position to the decreases
FULL position
EMPTY 71.7 ± 2.3 ohms
FULL 3.2 ± 0.7 ohms
W and 31 EMPTY (low Continuity
fuel warning)
23If the resistance readings are incorrect,
renew the sender unit.
24Refitting is the reverse of removal.
5 Fuel lines and fittings-
repair and renewal
3
Warning: Fuel is extremely
flammable, so take extra
precautions when you work on
any part of the fuel system. Don’t
smoke, or allow open flames or bare light
bulbs, near the work area. Don’t work in a
garage where a natural gas-type appliance
(such as a water heater or clothes dryer)
with a pilot light is present. If you spill any
fuel on your skin, rinse it off immediately
with soap and water. When you perform
any kind of work on the fuel system, wear
safety glasses, and have a fire
extinguisher on hand.
1Always disconnect the battery negative
cable, and (on fuel injection models)
depressurise the fuel system as described in
Section 2, before servicing fuel lines or
fittings.
2The fuel feed, return and vapour lines
extend from the fuel tank to the engine
compartment. The lines are secured to the
underbody with clip and screw assemblies.These lines must be occasionally inspected
for leaks, kinks and dents (see illustration).
3If evidence of dirt is found in the system or
fuel filter during dismantling, the lines should
be disconnected and blown out. On fuel
injection models, check the fuel strainer on
the in-tank fuel pump for damage and
deterioration.
4Because fuel lines used on fuel injection
vehicles are under high pressure, they require
special consideration. If renewal of a rigid fuel
line or emission line is called for, use welded
steel tubing meeting BMW specification or its
equivalent. Don’t use plastic, copper or
aluminium tubing to renew steel tubing. These
materials cannot withstand normal vehicle
vibration.
5When renewing fuel hoses, be sure to use
only hoses of original-equipment standard.6 Fuel tank-
removal and refitting
3
Warning: Fuel is extremely
flammable, so take extra
precautions when you work on
any part of the fuel system. Don’t
smoke, or allow open flames or bare light
bulbs, near the work area. Also, don’t work
in a garage where a natural gas-type
appliance with a pilot light is present.
When you perform any kind of work on the
fuel system, wear safety glasses, and have
a fire extinguisher on hand. If you spill any
fuel on your skin, clean it off immediately
with soap and water.
Note: To avoid draining large amounts of fuel,
make sure the fuel tank is nearly empty (if
possible) before beginning this procedure.
1Remove the fuel tank filler cap to relieve
fuel tank pressure.2On fuel injection models, depressurise the
fuel system (see Section 2).
3Detach the battery negative cable.
Caution: If the radio in your
vehicle is equipped with an anti-
theft system, make sure you
have the correct activation code
before disconnecting the battery. Refer to
the information on page 0-7 at the front of
this manual before detaching the cable.
Note: If, after connecting the battery, the
wrong language appears on the instrument
panel display, refer to page 0-7 for the
language resetting procedure.
4Remove the tank drain plug (see
illustration)and drain the fuel into an
approved fuel container. If no drain plug is
fitted, it should be possible to syphon the fuel
out (not by mouth), otherwise the fuel will have
to be drained during the removal operation.
5Unplug the fuel pump/sender unit electrical
connector (as applicable) and detach the fuel
feed, return and vapour hoses (see Section 4).
Where applicable, remove the rear seat
cushion for access.
6Remove the fuel tank shield (see
illustration).
7Detach the fuel filler neck and breather
hoses.
8Raise and support the vehicle. On some
models, it will also be necessary to remove
the exhaust system and propeller shaft.
9Support the tank with a trolley jack.
Fuel and exhaust systems 4•7
4.22b Fuel level sender unit terminal
designations on later Motronic systems -
check the sender unit resistance across
terminals 1 and 3 of the connector
1 Fuel level sender unit earth
2 Warning light
3 Sender unit
4 Fuel pump earth
5 Fuel pump4.22a Fuel level sender unit terminal
designations on L-Jetronic and early
Motronic systems
6.4 Remove the tank drain plug (arrowed)
and drain the fuel into a suitable container
5.2 When checking the fuel lines, don’t
overlook these short sections of fuel hose
attached to the main fuel rail - they’re a
common source of fuel leaks
4

Position a block of wood between the jack
head and the fuel tank to protect the tank.
10Remove the mounting bolts at the corners
of the fuel tank, and unbolt the retaining
straps (see illustrations). Pivot the straps
down until they’re hanging out of the way.11Lower the tank just enough so you can
see the top, and make sure you have
detached everything. Finish lowering the tank,
and remove it from the vehicle.
12Refitting is the reverse of removal.
7 Fuel tank cleaning and repair
- general information
1All repairs to the fuel tank or filler neck
should be carried out by a professional who
has experience in this critical and potentially
dangerous work. Even after cleaning and
flushing of the fuel system, explosive fumes
can remain and ignite during repair of the
tank.
2If the fuel tank is removed from the vehicle,
it should not be placed in an area where
sparks or open flames could ignite the fumes
coming out of the tank. Be especially careful
inside garages where a natural gas-type
appliance is located, because the pilot light
could cause an explosion.
8 Air cleaner assembly-
removal and refitting
1
1Detach the battery negative cable.
Caution: If the radio in your
vehicle is equipped with an anti-
theft system, make sure you
have the correct activation code
before disconnecting the battery. Refer to
the information on page 0-7 at the front of
this manual before detaching the cable.
Note: If, after connecting the battery, the
wrong language appears on the instrument
panel display, refer to page 0-7 for the
language resetting procedure.
Carburettor engines
2Release the spring clips, then unscrew the
centre nut and lift off the cover (see
illustrations).
3Remove the air filter element, and wipe
clean the air cleaner body and cover (see
illustration).
4To remove the body, first disconnect the
inlet duct and warm-air hose (see
illustration).
5Disconnect the vacuum line at the
carburettor.
4•8 Fuel and exhaust systems
8.3 Remove the air cleaner element, and
wipe clean the body and cover8.2b . . . then remove the air cleaner cover
centre nut, and lift off the cover8.2a Release the air cleaner cover spring
clips . . .
6.10a Remove the fuel tank mounting
bolts (one arrowed)6.10b Remove the retaining strap bolts
(one arrowed) and lower the fuel tank
6.6 Exploded view of the fuel tank assembly on later 5-Series models

Caution: If the radio in your
vehicle is equipped with an anti-
theft system, make sure you
have the correct activation code before
disconnecting the battery. Refer to the
information on page 0-7 at the front of this
manual before detaching the cable.
Note: If, after connecting the battery, the
wrong language appears on the instrument
panel display, refer to page 0-7 for the
language resetting procedure.
8Loosen the cable adjuster locknuts, and
detach the cable from its support bracket
located on the intake manifold (see
illustration).
9Pinch the plastic retainer with a pair of
needle-nose pliers, and push it out of the
bracket (see illustration).10Pull the cable down through the slot and
away from the bracket (see illustrations).
11Working from underneath the driver’s side
of the facia, reach up and detach the
accelerator cable from the top of the pedal.
12Pull the cable through the bulkhead, from
the engine compartment side.
13Refitting is the reverse of removal. Adjust
the cable as described earlier.
10 Carburettor-
general information
1Early models are fitted with a Solex 2B4
carburettor, and later models are fitted with a
Solex 2BE carburettor. Both carburettors are
of downdraught, two-stage type. The first
stage is operated mechanically by the
accelerator pedal, and the second stage by
vacuum control.
2Each stage has its own float chamber, float
assembly and needle valve, designed to
reduce the effects of braking and centrifugal
forces.
3On the 2B4 version, the primary stage
choke valve is operated by an automatic
choke (a bi-metal spring which is electrically
heated) during the warm-up period. Warm-up
enrichment is also provided by a coolant-
operated thermal valve and air temperature-
controlled flow valve.
4On the 2BE version, an electronic controlunit is used to automatically adjust the
carburettor settings during warm-up and
normal temperature operation. The control
unit is located beneath the right-hand side of
the facia.
11 Carburettor-
removal and refitting
2
Removal
1Remove the air cleaner as described in
Section 8.
2Disconnect the accelerator cable from the
carburettor with reference to Section 9.
3On automatic transmission models,
disconnect the kickdown cable.
4Disconnect the wiring from the carburettor,
noting the location of each wire.
5Remove the screw, and disconnect the
earth cable from the throttle positioner
bracket (see illustration).
6Disconnect the vacuum hoses, noting that
the hose with the white tracer is located on
the white plastic ‘T’ piece, and the distributor
vacuum hoses are located on the side of the
carburettor (see illustration).
7On the 2B4 carburettor, disconnect and
plug the coolant hoses from the TM (thermal
starter) valve.
8Disconnect the fuel supply hose (see
illustration).
4•10 Fuel and exhaust systems
11.8 Disconnect the fuel supply hose
(arrowed)11.6 Note the locations of the carburettor
vacuum hoses (arrowed) before
disconnecting them11.5 Remove the screw, and disconnect
the carburettor earth cable (arrowed)
9.10b After the cable is off the throttle
valve assembly, remove the plastic
retainer from the cable
9.10a Rotate the throttle valve and remove
the cable end from the slotted portion of
the valve9.9 Pinch the plastic retainer, and push it
through the bracket recess on the throttle
valve9.8 Push the rubber grommet from the
rear, and separate the cable from the
bracket