warning light BMW 3 SERIES 1985 E30 User Guide

Flushing
7Once the system is completely drained,
flush the radiator with fresh water from a
garden hose until the water runs clear at the
drain or bottom hose. If the radiator is
severely corroded, damaged or leaking, it
should be removed (see Chapter 3) and taken
to a radiator repair specialist.
8Flushing in this way will remove sediments
from the radiator, but will not remove rust and
scale from the engine and cooling tube
surfaces. These deposits can be removed by
using a chemical cleaner. Follow the
procedure outlined in the cleaner
manufacturer’s instructions. Remove the
cylinder block drain plug before flushing the
engine.
9On models so equipped, remove the
overflow hose from the coolant recovery
reservoir. Drain the reservoir and flush it with
clean water, then reconnect the hose.
Refilling
10Tighten the radiator drain plug, or
reconnect the radiator bottom hose. Refit and
tighten the cylinder block drain plug.
Four-cylinder engines
11Slowly add new coolant (a 40%/60%
mixture of antifreeze to water) to the radiator
until it is full. Add coolant to the reservoir up
to the lower mark.
12Leave the radiator cap off, and run the
engine in a well-ventilated area until the
thermostat opens (coolant will begin flowing
through the radiator, and the upper radiator
hose will become hot).
13Turn the engine off, and let it cool. Add
more coolant mixture to bring the coolant
level back up to the lip on the radiator filler
neck. On the M40 engine, unscrew the bleed
screw from the top of the radiator, and add
coolant until it comes out of the bleed screw
hole. Refit and tighten the bleed screw.
14Squeeze the upper radiator hose to expel
air, then add more coolant mixture if
necessary. Refit the radiator cap.
15Start the engine, allow it to reach normal
operating temperature, and check for leaks.
Six-cylinder engines
16Loosen the bleed screw in the thermostat
housing (see illustration)
17Fill the radiator with a 40%/60% solution
of antifreeze and water until it comes out of
the bleed screw opening. Tighten the bleed
screw.
18Refit the radiator cap, and run the engine
until the thermostat opens (the upper radiator
hose will become hot). Slowly loosen the
bleed screw until no bubbles emerge, then
tighten the screw.
19Repeat the procedure until the air is bled
from the system.
30 Fuel filter renewal
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. 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.
1On fuel injection engines, depressurise the
fuel system (see Chapter 4).
2The fuel filter is located in the engine
compartment on the bulkhead, or under the
vehicle adjacent to the fuel tank.
3Because on some models the filter is
located adjacent to the starter motor, fuel
could leak onto the electrical connections. For
safety reasons, therefore, disconnect the
battery negative cable before beginning work.
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.
4Place a pan or rags under the fuel filter to
catch any spilled fuel. If suitable hose clamps
are available, clamp the inlet and outlet hoses.
5 Detach the hoses and remove the bracket
screws/nuts, then remove the filter and where
applicable the bracket assembly (see
illustration).
6Detach the filter from the bracket.
7Refitting is the reverse of removal. Be sure
the arrow on the filter points in the direction of
fuel flow.
31 Manual transmission
lubricant change
1
1Tools necessary for this job include axle
stands to support the vehicle in a raised
position, an Allen key to remove the drain
plug, a drain pan, newspapers and clean rags.
The correct amount of the specified lubricant
should also be available (see “Lubricants and
fluids”at the start of this Chapter).
2The lubricant should be drained when it is
hot (ie immediately after the vehicle has been
driven); this will remove any contaminants
better than if the lubricant were cold. Because
1•25
30.5 To renew the fuel filter, disconnect
the hoses (A), then unscrew the nut (B) and
detach the filter from the bracket (fuel
injection type shown)29.16 The bleed screw (arrowed) is
located on the thermostat housing (six-
cylinder models)29.4 Radiator drain plug location
(arrowed) - not fitted to all models
31.5 Use an Allen key to remove the drain
plug (arrowed) from the bottom of the
transmission
1
Every 24 000 miles

the lubricant will be hot, it would be wise to
wear rubber gloves.
3Raise the vehicle and place it on axle
stands. Make sure it is safely supported, and
as level as possible.
4Move the necessary equipment under the
vehicle, being careful not to touch any of the
hot exhaust components.
5Place the drain pan under the transmission,
and remove the filler/level plug from the side
of the transmission. Loosen the drain plug
(see illustration).
6Carefully remove the drain plug. Be careful
not to burn yourself on the lubricant.
7Allow the lubricant to drain completely.
Clean the drain plug thoroughly, then refit and
tighten it securely.
8Refer to Section 16 and fill the transmission
with new lubricant, then refit the filler/level
plug, tightening it securely.
9Lower the vehicle. Check for leaks at the
drain plug after the first few miles of driving.
32 Differential lubricant change
1
1Drive the vehicle for several miles to warm
up the differential lubricant, then raise the
vehicle and support it securely on axle stands.
2Move a drain pan, rags, newspapers and an
Allen key under the vehicle. Since the
lubricant will be hot, wear rubber gloves to
prevent burns.
3Remove the filler/level plug from the
differential; this is the upper of the two plugs.
4With the drain pan under the differential,
loosen the drain plug; this is the lower of the
two plugs (see illustration).
5Carefully unscrew the drain plug until you
can remove it from the case.
6Allow all the oil to drain into the pan, then
refit the drain plug and tighten it securely.
7Refer to Section 17 and fill the differential
with lubricant.
8Refit the filler/level plug and tighten it
securely.
9Lower the vehicle. Check for leaks at the
drain plug after the first few miles of driving.
33 Evaporative emissions
control (EVAP) system check
1
1The function of the evaporative emissions
control system is to draw fuel vapours from
the tank and fuel system, store them in a
charcoal canister, and then burn them during
normal engine operation. This system is
normally only fitted to those vehicles
equipped with a catalytic converter.
2The most common symptom of a fault in
the evaporative emissions system is a strong
fuel odour in the engine compartment. If a fuel
odour is detected, inspect the charcoal
canister and system hoses for cracks. The
canister is located in the front corner of the
engine compartment on most models (see
illustration).
3Refer to Chapter 6 for more information on
the evaporative emissions system.
34 Service indicator light
resetting
4
Service indicator lights
1All models covered in this manual are
equipped with various service indicator lights
on the facia, which automatically go on when
the mileage interval is reached. These lights
can only be turned off by using a special tool
which plugs into the service connector
located in the engine compartment.
2Although the service light resetting tool can
be obtained from a dealer, reasonably-priced
alternatives may also be available from
aftermarket sources. When obtaining a tool, it
is important to know the vehicle year and
model, and whether the service connector has
15 or 20 pins (see illustrations). Once the
proper tool is obtained, it is a simple matter to
plug it into the service connector and,
following the tool manufacturer’s instructions,
reset the service lights. Note: The brake
warning light will not automatically reset if the
sensor on the brake pad (or its wiring) isdamaged because it is worn through: it must
be repaired first.
3The service lights are controlled by the
Service Indicator (SI) board in the instrument
cluster, which is powered by rechargeable
batteries. Should these batteries fail,
problems will develop in the SI board.
Symptoms of failed batteries include the
inability to reset the service lights and
malfunctions affecting the tachometer,
temperature gauge and radio operation. Refer
to Chapter 12 for more information on the SI
board.
Every 60 000 miles
35 Engine timing belt renewal
5
Note:This is not included in the
manufacturer’s maintenance schedule, but is
strongly recommended as a precaution
against the timing belt failing in service. If the
timing belt fails while the engine is running,
extensive engine damage could be caused.
Refer to Chapter 2A, Section 10.
1•26
34.2b An aftermarket service light
resetting tool such as this one can be
plugged into the service connector and
used to reset the service lights
34.2a The earlier 15-pin connector
(arrowed) is mounted near the front of the
engine. The 20-pin connector used on later
models is located in the left rear corner of
the engine compartment33.2 Inspect the hoses (arrowed) at the
top of the evaporative emissions charcoal
canister for damage32.4 Remove the differential drain plug
with an Allen key
Every 24 000 miles

the crankshaft flange (see illustration). Be
careful - the flywheel is heavy.
5To refit the flywheel/driveplate on the
crankshaft, use a liquid thread-locking
compound on the bolts, and tighten them
gradually, using a criss-cross pattern, to the
torque listed in this Chapter’s Specifications.
6The remainder of refitting is the reverse of
removal.
16 Crankshaft rear oil seal-
renewal
3
1Remove the flywheel or driveplate (see
Section 15).
2Remove the bolts and/or nuts attaching the
seal retainer to the engine block. Be sure to
remove the two bolts (from underneath)
connecting the rear of the sump to the bottom
of the seal retainer (see illustration).
3Run a sharp, thin knife between the sump
gasket and the seal retainer, cutting the
retainer free from the gasket. Be very careful
not to damage the gasket, and keep it clean
so you can re-use it.
4Break the seal retainer-to-block gasket seal
by tapping the retainer with a plastic mallet or
block of wood and hammer. Do not prise
between the retainer and the engine block, as
damage to the gasket sealing surfaces will
result.
5Using a scraper, remove all traces of old
gasket material from the sealing surfaces of
the retainer and engine block. Gasket removal
solvents are available at car accessory shops,
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.
Caution: Be very careful not to
scratch or gouge the delicate
aluminium surfaces. Also, do not
damage the sump gasket, and
keep it clean.
6Support the retainer on two blocks of
wood, and drive out the seal from behind with
a hammer and screwdriver (see illustration).Be very careful not to damage the seal bore in
the process.
7Coat the outside diameter and lip of the
new seal with multi-purpose grease, and drive
the seal into the retainer with a hammer and a
block of wood (see illustration).
8Apply a film of RTV-type gasket sealant to
the surface of the sump gasket that mates with
the seal retainer. 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 rear portion
of the gasket off at the point where it meets the
engine block, then trim off the rear 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.
9Coat both sides of the new retainer gasket
with RTV-type gasket sealant, then attach the
gasket to the seal retainer. Fit the seal retainer
to the rear of the engine, then 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
retainer-to-block bolts first, then tighten the
sump-to-retainer bolts.Note 2:After applying
RTV-type sealant, reassembly must becompleted in about 10 minutes so the RTV
won’t prematurely harden.
10Refit the flywheel/driveplate (see Sec-
tion 15).
11Refit the transmission (on vehicles with
manual transmission, see Chapter 7A; on
vehicles with automatic transmission, see
Chapter 7B).
17 Engine mountings-
check and renewal
1
1Engine mountings seldom require attention,
but broken or deteriorated mountings should
be renewed immediately, or the added strain
placed on the driveline components may
cause damage or wear.
Check
2During the check, the engine must be
raised slightly to remove its weight from the
mounts.
3Raise the vehicle and support it securely on
axle stands, then position a jack under the
engine sump. Place a large block of wood
between the jack head and the sump, then
carefully raise the engine just enough to take
its weight off the mounts.
Warning: DO NOT place any part
of your body under the engine
when it’s supported only by a
jack!
In-car engine repair procedures 2A•19
16.6 After removing the retainer from the
block, support it on two wood blocks, and
drive out the old seal with a punch and
hammer16.2 Remove the six bolts from the rear of
the block and the two from underneath at
the sump15.4 Using a socket and ratchet, remove
the eight bolts that hold the flywheel/
driveplate to the crankshaft flange - prevent
the flywheel/driveplate from turning by
locking the ring gear with a lever
17.4 As engine mountings wear or age,
they should be inspected for cracking or
separation from their metal plates
16.7 Drive the new seal into the retainer
with a block of wood, or a section of pipe,
if you have one large enough - make sure
the seal enters the retainer bore squarely
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

M10, M20 and M30 engines
3Adjust all valves to their maximum clearance
by rotating the eccentric on the valve end of
the rocker arm towards the centre of the head
(see Chapter 1, if necessary).
4Before removing the thrustplate, measure
the camshaft endfloat by mounting a dial
indicator to the front end of the cylinder head,
with the probe resting on the camshaft (see
illustration). Prise the camshaft back-and-
forth in the cylinder head. The reading is the
camshaft endfloat. Compare the reading to
this Chapter’s Specifications.
5Unbolt and remove the camshaft
thrustplate. Note:There are two different
locations for the thrustplate. On M10 and M30
engines, it is attached on the front of the
cylinder head, behind the timing gear flange.
On M20 and M40 engines, the thrustplate is
located inside the head, by the rocker shafts,
at the forward end of the cylinder head.
6Remove the rear cover plate from the back
of the cylinder head (see illustration).
7Remove the retaining clips from each of the
rocker arms. Note:There is more than one
style of clip. The wire-type clips (see
illustration)are fitted one each side of the
rocker arm; the spring-steel-type goes over
the rocker arm, and clips onto either side of it.
8Before removing the rocker arm shafts,
measure the rocker arm radial clearance,
using a dial indicator, and compare your
measurement to the Specifications at thebeginning of this Chapter. Without sliding the
rocker arm along the shaft, try to rotate the
rocker arm against the shaft in each direction
(see illustration). The total movement
measured at the camshaft end of the rocker
arm is the radial clearance. If the clearance is
excessive, either the rocker arm bush, rocker
arm shaft, or both, will need to be renewed.
9Remove the rubber retaining plugs, or the
threaded plugs, at the front of the cylinder
head, as applicable. There is a plug in front of
each rocker shaft.
Caution: If your engine has
welded-in retaining plugs at the
front of the rocker shafts, take
the cylinder head to a machine
shop for plug removal, to avoid possible
damage to the cylinder head or the rocker
arm shafts.
10Rotate the camshaft until the most rocker
arms possible are loose (not compressing
their associated valve springs).
11For the remaining rocker arms that are still
compressing their valve springs, BMW
recommends using a special forked tool to
compress the rocker arms against the valve
springs (and therefore take the valve spring
tension off the camshaft lobe). If the tool is not
available, insert a standard screwdriver into the
gap above the adjuster eccentric at the valve-
end tip of each rocker arm. Using thescrewdrivers, prise the rocker arms against the
valve springs, and hold them in place as the
camshaft is removed (see the next paragraph).
At least one assistant will be necessary for this
operation, since three or four valve springs
usually need compressing. If no assistance is
available, you could try retaining the
screwdrivers that are compressing the valve
springs to the bench with lengths of sturdy wire.
Warning: Be sure the wire is
securely attached to the bench
and screwdrivers, or the
screwdrivers could fly off the cylinder
head, possibly causing injury.
12When all the rocker arms are no longer
contacting the camshaft lobes, slowly and
carefully pull the camshaft out the front of the
cylinder head. It may be necessary to rotate
the camshaft as it is removed.
Caution: Be very careful not to
scratch the camshaft bearing
journals in the cylinder head as
the camshaft is withdrawn.
13After removing the camshaft, carefully
remove the rocker arm shafts. On models
without threaded holes at the front of the
shafts, drive them out from the rear of the
cylinder head with a hammer and hardwood
dowel that is slightly smaller in diameter than
the rocker arm shaft (see illustration). For
2B•8 General engine overhaul procedures
8.13 Removing a rocker arm shaft from
the front of the cylinder head - the shaft
must be either driven out from the rear of
the head with a hardwood dowel or, on
models where the rocker shaft is threaded
at the front, pulled out from the front with
a slide-hammer-type puller
8.8 Check the rocker arm-to-shaft radial
clearance by setting up a dial indicator as
shown, and trying to rotate the rocker arm
against the shaft - DO NOT slide the rocker
arm along the shaft
8.7 Remove the retaining clips from the
rocker arms - the wire-type clip is shown
here
8.6 Remove the cover from the rear of the
cylinder head - be sure to note the
locations of any washers, gaskets and
seals while you are removing the cover8.4 To check camshaft endfloat, mount a
dial indicator so that its stem is in-line with
the camshaft and just touching the
camshaft at the front8.2b Removing the oil tube from the
camshaft bearing caps on the top of the
cylinder head (M40 engine)

5Gently tap the caps with a soft-faced
hammer, then separate them from the engine
block. If necessary, use the bolts as levers to
remove the caps. Try not to drop the bearing
shells if they come out with the caps.
6Carefully lift the crankshaft out of the
engine. It may be a good idea to have an
assistant available, since the crankshaft is
quite heavy (see illustration). With the
bearing shells in place in the engine block and
main bearing caps, return the caps to their
respective locations on the engine block, and
tighten the bolts finger-tight.
14 Intermediate shaft-
removal and inspection
5
Note:The intermediate shaft is used on the
M20 engine only. The shaft rotates in the
engine block parallel to the crankshaft. It is
driven by the timing belt, and its only purpose
is to drive the oil pump.
1Remove the timing belt (see Chapter 2A).
2With the belt removed, unbolt the gear from
the intermediate shaft and unbolt the front
cover.
3Remove the oil pump driveshaft (see
Chapter 2A).
4The shaft is held in the cylinder block by a
retaining plate with two bolts. Remove the
bolts, and pull the shaft forwards and out of
the block.
5Look for any signs of abnormal wear on the
bearing surfaces or the gear at the back end
of the shaft, which drives the oil pump shaft. If
the bearing surfaces in the engine block show
wear, they’ll have to be attended to by a
machine shop.
15 Engine block- cleaning
2
Caution: The core plugs may be
difficult or impossible to retrieve
if they’re driven into the block
coolant passages.
1Remove the core plugs from the engine
block. To do this, knock one side of each plug
into the block with a hammer and punch,
grasp the other side by its edge with large
pliers, and pull it out.
2Using a gasket scraper, remove all traces of
gasket material from the engine block. Be very
careful not to nick or gouge the gasket sealing
surfaces.
3Remove the main bearing caps, and
separate the bearing shells from the caps and
the engine block. Tag the bearings, indicating
which cylinder they were removed from and
whether they were in the cap or the block,
then set them aside.
4Remove all of the threaded oil gallery plugs
from the block. The plugs are usually very
tight - they may have to be drilled out and theholes retapped. Use new plugs when the
engine is reassembled.
5If the engine is extremely dirty, it should be
taken to a machine shop to be steam-
cleaned.
6After the block is returned, clean all oil
holes and oil galleries one more time. Brushes
specifically designed for this purpose are
available at most motor factors. Flush the
passages with warm water until the water runs
clear, dry the block thoroughly, and wipe all
machined surfaces with a light, rust-
preventive oil. If you have access to
compressed air, use it to speed the drying
process and to blow out all the oil holes and
galleries.
Warning: Wear eye protection
when using compressed air!
7If the block isn’t extremely dirty or sludged
up, you can do an adequate cleaning job with
hot soapy water and a stiff brush. Take plenty
of time, and do a thorough job. Regardless of
the cleaning method used, be sure to clean all
oil holes and galleries very thoroughly, dry the
block completely, and coat all machined
surfaces with light oil.
8The threaded holes in the block must be
clean to ensure accurate torque readingsduring reassembly. Run the proper-size tap
into each of the holes to remove rust,
corrosion, thread sealant or sludge, and to
restore damaged threads (see illustration). If
possible, use compressed air to clear the
holes of debris produced by this operation. Be
sure also that the holes are dry- any oil or
other fluid present could cause the block to
be cracked by hydraulic pressure when the
bolts are tightened. Now is a good time to
clean the threads on all bolts. Note that BMW
recommend that the cylinder head bolts and
main bearing bolts are renewed as a matter of
course.
9Refit the main bearing caps, and tighten the
bolts finger-tight.
10After coating the sealing surfaces of the
new core plugs with a suitable sealant, refit
them in the engine block (see illustration).
Make sure they’re driven in straight and
seated properly, or leakage could result.
Special tools are available for this purpose,
but a large socket, with an outside diameter
that will just slip into the core plug, a 1/2-inch
drive extension, and a hammer, will work just
as well.
11Apply non-hardening sealant to the new
oil gallery plugs, and thread them into the
holes in the block. Make sure they’re
tightened securely.
12If the engine isn’t going to be
reassembled right away, cover it with a large
plastic bag to keep it clean.
2B•14 General engine overhaul procedures
15.10 A large socket on an extension can
be used to drive the new core plugs into
the block
15.8 All bolt holes in the block -
particularly the main bearing cap and head
bolt holes - should be cleaned and
restored with a tap (be sure to remove
debris from the holes after this is done)
13.6 Remove the crankshaft by lifting
straight up. Be very careful when removing
the crankshaft - it is very heavy13.4 Use a centre-punch or number-
stamping dies to mark the main bearing
caps to ensure refitting in their original
locations on the block (make the punch
marks near one of the bolt heads)

the bearing - use your fingernail or the edge of
a credit card.
20Make sure the bearing faces are perfectly
clean, then apply a uniform layer of
molybdenum disulphide (“moly”) grease or
engine assembly oil to both of them. You’ll
have to push the piston into the cylinder to
expose the face of the bearing shell in the
connecting rod - be sure to slip the protective
hoses over the rod bolts first, where
applicable.
21Slide the connecting rod back into place
on the journal, and remove the protective
hoses from the rod cap bolts. Refit the rod
cap, and tighten the nuts/bolts to the
specified torque.
22Repeat the entire procedure for the
remaining pistons/connecting rods.
23The important points to remember are:
a) Keep the back sides of the bearing shells
and the insides of the connecting rods
and caps perfectly clean when
assembling them.
b) Make sure you have the correct
piston/rod assembly for each cylinder.
c) The notch or mark on the piston must
face the front of the engine.
d) Lubricate the cylinder walls with clean oil.
e) Lubricate the bearing faces when refitting
the rod caps after the oil clearance has
been checked.
24After all the piston/connecting rod
assemblies have been properly fitted, rotate
the crankshaft a number of times by hand to
check for any obvious binding.25Check the connecting rod side play (see
Section 13).
26Compare the measured side play to the
Specifications to make sure it’s correct. If it
was correct before dismantling, and the
original crankshaft and rods were refitted, it
should still be right. If new rods or a new
crankshaft were fitted, the side play may be
incorrect. If so, the rods will have to be
removed and taken to a machine shop for
attention.
27 Initial start-up and running-
in after overhaul
1
Warning:Have a fire extinguisher
handy when starting the engine
for the first time.
1Once the engine has been refitted in the
vehicle, double-check the engine oil and
coolant levels.
2With the spark plugs removed and the
ignition system disabled (see Section 3), crank
the engine until oil pressure registers on the
gauge, or until the oil pressure warning light
goes out.
3Refit the spark plugs, connect the HT leads,
and restore the ignition system functions (see
Section 3).
4Start the engine. It may take a few
moments for the fuel system to build uppressure, but the engine should start without
a great deal of effort. Note: If backfiring
occurs through the throttle body or
carburettor, check the valve timing (check that
the timing chain/belt has been correctly fitted),
the firing order (check the fitted order of the
spark plug HT leads), and the ignition timing.
5After the engine starts, it should be allowed
to warm up to normal operating temperature.
While the engine is warming up, make a
thorough check for fuel, oil and coolant leaks.
6Shut the engine off and recheck the engine
oil and coolant levels.
7Drive the vehicle to an area with minimum
traffic, accelerate at full throttle from 30 to
50 mph, then lift off the throttle completely,
and allow the vehicle to slow to 30 mph with
the throttle closed. Repeat the procedure
10 or 12 times. This will load the piston rings,
and cause them to seat properly against the
cylinder walls. Check again for oil and coolant
leaks.
8Drive the vehicle gently for the first
500 miles (no sustained high speeds) and
keep a constant check on the oil level. It is not
unusual for an engine to use oil during the
running-in period.
9At approximately 500 to 600 miles, change
the oil and filter.
10For the next few hundred miles, drive the
vehicle normally - don’t nurse it, but don’t
abuse it, either.
11After 2000 miles, change the oil and filter
again. The engine may now be considered to
be fully run-in.
2B•22 General engine overhaul procedures

Warning: Do not remove the
pressure cap from the radiator or
expansion tank until the engine
has cooled completely and
there’s no pressure remaining in the
cooling system. Removing the cap from a
hot engine risks personal injury by
scalding.
Heating system
The heating system consists of a blower fan
and heater matrix located in the heater box,
with hoses connecting the heater matrix to the
engine cooling system, and the heater/air
conditioning control head on the dashboard.
Hot engine coolant is circulated through the
heater matrix passages all the time the engine
is running. Switching the heater on opens a
flap door to direct air through the heater
matrix, and the warmed air enters the
passenger compartment. A fan switch on the
control head activates the blower motor,
which forces more air through the heater
matrix, giving additional heater output for
demisting, etc.
Air conditioning system
The air conditioning system consists of a
condenser mounted in front of the radiator, an
evaporator mounted adjacent to the heater
matrix, a compressor mounted on the engine,
a filter-drier (receiver-drier) which contains a
high-pressure relief valve, and the plumbing
connecting all of the above components.
A blower fan forces the warmer air of the
passenger compartment through the
evaporator matrix (a radiator-in-reverse),
transferring the heat from the air to the
refrigerant. The liquid refrigerant boils off into
low-pressure vapour, taking the heat with it
when it leaves the evaporator.
Note: Refer to the precautions at the start
of Section 12 concerning the potential
dangers associated with the air conditioning
system.
2 Antifreeze-
general information
Warning: Do not allow antifreeze
to come in contact with your skin
or painted surfaces of the
vehicle. Rinse off spills
immediately with plenty of water. If
consumed, antifreeze can be fatal;
children and pets are attracted by its
sweet taste, so wipe up garage floor and
drip pan coolant spills immediately. Keep
antifreeze containers covered, and repair
leaks in your cooling system as soon as
they are noticed.
The cooling system should be filled with a
60/40% water/ethylene-glycol-based anti-
freeze solution, which will prevent freezing
down to approximately -27°C (-17°F). The
antifreeze also raises the boiling point of thecoolant, and (if of good quality) provides
protection against corrosion.
The cooling system should be drained,
flushed and refilled at the specified intervals
(see Chapter 1). Old or contaminated
antifreeze solutions are likely to cause
damage, and encourage the formation of rust
and scale in the system. Use distilled water
with the antifreeze, if available, or clean
rainwater. Tap water will do, but not if the
water in your area is at all “hard”.
Before adding antifreeze, check all hose
connections, because antifreeze tends to
search out and leak through very minute
openings. Engines don’t normally consume
coolant, so if the level goes down, find the
cause and correct it.
The antifreeze mixture should be
maintained at its correct proportions; adding
too much antifreeze reduces the efficiency of
the cooling system. If necessary, consult the
mixture ratio chart on the antifreeze container
before adding coolant. Hydrometers are
available at most car accessory shops to test
the coolant. Use antifreeze which meets the
vehicle manufacturer’s specifications.
3 Thermostat-
check and renewal
1
Warning: Do not remove the
radiator cap, drain the coolant, or
renew the thermostat until the
engine has cooled completely.
Check
1Before assuming the thermostat is to blame
for a cooling system problem, check the
coolant level, drivebelt tension (see Chapter 1)
and temperature gauge (or warning light)
operation.
2If the engine seems to be taking a long time
to warm up (based on heater output or
temperature gauge operation), the thermostat
is probably stuck open. Renew the
thermostat.
3If the engine runs hot, use your hand to
check the temperature of the upper radiator
hose. If the hose isn’t hot, but the engine is,
the thermostat is probably stuck closed,preventing the coolant inside the engine from
circulating to the radiator. Renew the
thermostat.
Caution: Don’t drive the vehicle
without a thermostat. The engine
will be very slow to warm-up in
cold conditions, resulting in poor
fuel economy and driveability. A new
thermostat is normally an inexpensive
component anyway.
4If the upper radiator hose is hot, it means
that the coolant is flowing and the thermostat
is at least partly open. Consult the “Fault
finding” Section at the rear of this manual for
cooling system diagnosis.
Renewal
All models
5Disconnect the negative cable from the
battery.
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.
6Drain the cooling system (see Chapter 1). If
the coolant is relatively new or in good
condition, save it and re-use it.
M10 engines
7The thermostat is located in the bottom
hose. First remove the cooling fan.
8Note the fitted position of the thermostat,
then unscrew the hose clamps and withdraw
the thermostat from the hose connections
(see illustration).
9Refit the thermostat-to-hose connections,
and tighten the hose clamps.
10Refit the cooling fan.
M20 and M30 engines
11Loosen the hose clamp (see illustration),
then detach the hose(s) from the thermostat
cover.
3•2 Cooling, heating and air conditioning systems
3.11 On M20 and M30 engine models,
loosen the hose clamp (A) and disconnect
the hose from the thermostat housing
cover - note that the coolant temperature
sender unit (barely visible behind the fuel
pressure regulator) is located at the top of
the thermostat housing (B)
3.8 On the M10 (four-cylinder) engine, the
thermostat (arrowed) is connected in-line
in the radiator hose

disconnect the fluid cooler lines from the
radiator. Use a drip tray to catch spilled fluid.
Plug the fluid cooler lines and fittings.
7Disconnect the coolant sensors located on
the radiator (see illustration). The thermo-
statically-controlled switches for high- and
low-speed operation of the auxiliary fan are
located in the radiator tanks, in various
locations depending on engine and model.
8Remove the radiator mounting bolt(s). The
mountings are either on the top or sides of the
radiator (see illustration).
9Carefully lift out the radiator from the
bottom mountings, taking care not to damage
the cooling fins. Don’t spill coolant on the
vehicle, or scratch the paint.
10With the radiator removed, it can be
inspected for leaks and damage. If it needs
repair, have a specialist perform the work, as
special techniques are required.
11Flies and dirt can be removed from the
radiator with compressed air and a soft brush.
Don’t bend the cooling fins as this is done.
12Check the radiator mountings for
deterioration, and renew if necessary (see
illustration).
Refitting
13Refitting is the reverse of the removal
procedure.
14After refitting, fill the cooling system with
the proper mixture of antifreeze and water.
Refer to Chapter 1 if necessary.15Start the engine and check for leaks.
Allow the engine to reach normal operating
temperature, indicated by the upper radiator
hose becoming hot. Recheck the coolant
level, and add more if required.
16If you’re working on an automatic
transmission model, check and add
transmission fluid as needed.
5 Engine cooling fan(s) and
clutch- check, removal and
refitting
1
Warning: To avoid possible injury
or damage, DO NOT operate the
engine with a damaged fan. Do
not attempt to repair fan blades -
fit a new fan. Also, the electric auxiliary fan
in front of the radiator or air conditioning
condenser can come on without the
engine running or ignition being on. It is
controlled by the coolant temperature of
the thermo-switches located in the
radiator.
Check
Electric auxiliary fan
Note: This fan on most models is controlled
by two thermo-switches placed in the radiator:
one for low-speed/low-temperature operation,
and one for high-speed/high-temperature
operation. Each switch comes on at a different
coolant temperature (refer to the Specifica-
tions at the beginning of this Chapter).
1The thermostatically-controlled switches for
high- and low-speed operation of the auxiliary
fan are fitted in various locations in the
radiator (see illustration 4.7), depending on
engine or model. Two single switches, or one
dual switch, may be fitted.
2Insert a small screwdriver into the
connector to lift the lock tab, and unplug the
fan wire harness.
3To test the fan motor, unplug the electrical
connector at the motor, and use jumper wires
to connect the fan directly to the battery. If the
fan doesn’t work when connected directly to
the battery, the motor is proved faulty, and
must be renewed. If the fan works, there’s agood chance the switch is malfunctioning. To
more accurately diagnose the problem, follow
the steps that apply to your model. Note: Spin
the auxiliary fan motor by hand, to check that
the motor or fan isn’t binding. Make sure,
however, that the engine is sufficiently cool
that there is no danger of the fan cutting-in on
its own when this is done.
4To test the low-speed and high-speed
circuits, disconnect the electrical connector
from one of the fan switches, and bridge the
terminals of the switch’s electrical connector
with a short piece of wire. The fan should run
at low or high speed, depending on which
switch has been disconnected. On some
models the ignition must be on before the fan
will run.
5Repeat the test at the other switch so that
both high and low speeds are tested.
6If the low-speed and high-speed circuits
are OK, but there has been a problem with the
fan not operating correctly in service, renew
the switch (or switches). To remove a switch,
drain the coolant below the level of the switch
(see Chapter 1), then unscrew the switch and
screw in the new one. Refill the system with
coolant.
7If the switches are satisfactory, but the
motor still does not operate, the problem lies
in the fuse, the relay, the wiring which
connects the components (or the fan motor
itself). Carefully check the fuse, relay, all
wiring and connections. See Chapter 12 for
more information on how to carry out these
checks.
Mechanical fan with viscous clutch
8Disconnect the battery negative cable, and
rock the fan back and forth by hand to check
for excessive bearing play.
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.
9With the engine cold, turn the fan blades by
hand. The fan should turn with slight
resistance.
10Visually inspect for substantial fluid
leakage from the fan clutch assembly. If
problems are noted, renew the fan clutch
assembly.
11With the engine completely warmed up,
turn off the ignition switch and disconnect the
battery negative cable. Turn the fan by hand.
Heavier resistance should be evident. If the
fan turns easily, a new fan clutch may be
needed.
Removal and refitting
Electric auxiliary fan
12Disconnect the battery negative cable.
13To remove the auxiliary fan follow the
procedure that applies to your vehicle.
3•4 Cooling, heating and air conditioning systems
4.12 When the radiator is out, the radiator
mountings can be inspected - check for
signs of deterioration, and renew them, if
needed
4.8 The radiator is bolted to the front
panel at either the sides or the top of the
radiator4.7 Sensors that control the high- and
low-speed operation of the auxiliary
cooling fan are located in various places in
the radiator tanks