Engine mount BMW 3 SERIES 1988 E30 Owner's Manual

alignment mark on the camshaft sprocket and
rear timing cover to ensure correct refitting.
6On the M20 engine, loosen the two
tensioner roller retaining bolts a little, and
push the tensioner towards the water pump
(see illustration). With the timing belt tension
relieved, re-tighten the retaining bolt.
7On the M40 engine, loosen the tensioner
retaining nut, and use an Allen key to rotate
the tensioner clockwise. This will relieve the
tension of the timing belt. Tighten the
retaining nut to hold the tensioner in its free
position.
8If the same belt is to be refitted, mark it with
an arrow indicating direction of rotation.
Caution: It is not advisable to
refit a timing belt which has been
removed unless it is virtually
new. On the M40 engine, BMW
recommend that the timing belt is
renewed every time the tensioner roller is
released.
9Remove the timing belt by slipping it off the
roller(s) and the other sprockets (see
illustrations).
10If it’s necessary to remove the camshaft
or the intermediate shaft sprocket, remove the
sprocket bolt while holding the sprocket to
prevent it from moving. To hold the sprocket,
wrap it with a piece of an old timing belt
(toothed side engaging the sprocket teeth) ora piece of leather, then hold the sprocket
using a strap spanner. If a strap spanner is not
available, clamp the ends of the piece of belt
or leather tightly together with a pair of grips.
Before loosening the bolt, make sure you have
the necessary tool for positioning the
camshaft as described in the following
paragraph (see illustration).
Caution: Do not use the timing
belt you’re planning to refit to
hold the sprocket. Also, be sure
to hold the camshaft sprocket
very steady, because if it moves more than
a few degrees, the valves could hit the
pistons.
Note: On the M40 engine, the sprocket is not
directly located on the camshaft with a key, as
the groove in the end of the camshaft allows
the sprocket to move several degrees in either
direction. The retaining bolt locks the sprocket
onto a taper after positioning the camshaft
with a special tool.
11The BMW tool for positioning the camshaft
on the M40 engine consists of a metal plate
which locates over the square lug near the No
1 cylinder lobes on the camshaft - the valve
cover must be removed first (see
illustrations). If the BMW tool cannot be
obtained, a home-made tool should be
fabricated out of metal plate. The tool must be
made to hold the square lug on the camshaft
at right-angles to the upper face of the cylinder
head (ie the contact face of the valve cover).
12If it’s necessary to remove the crankshaft
sprocket, remove the crankshaft hub centre
bolt while holding the crankshaft steady.
Note:The removal of the crankshaft hub
mounting bolt requires a heavy-duty holding
device because of the high torque used to
tighten the bolt. BMW has a special tool,
numbered 112150 (M20 engines) or 112170
(M40 engines), for this purpose. If this tool
cannot be bought or borrowed, check with a
tool dealer or motor factors for a tool capable
of doing the job. Note that the tool number
112170 bolts on the rear of the cylinder head
and engages with the flywheel ring gear, so it
will only be possible to use this tool if the
gearbox has been removed, or if the engine is
out of the vehicle (see illustrations). On
2A•10 In-car engine repair procedures
10.12a Home-made tool for holding the
crankshaft stationary while the crankshaft
pulley bolt is being loosened (engine
removed for clarity)
10.11b The BMW camshaft-holding tool in
position on the M40 engine10.11a The BMW tool for holding the
camshaft in the TDC position on
M40 engines
10.10 Removing the camshaft sprocket on
the M40 engine
10.9b Removing the timing belt from the
camshaft sprocket on the M40 engine
10.9a When removing the timing belt on
models with a two-piece crankshaft hub,
it’s a tight fit to remove it around the hub,
but it’s a lot easier than removing the
crankshaft hub assembly, which is secured
by a very tight bolt10.6 Loosen the idler pulley bolts
(arrowed) to relieve the tension on the
timing belt so it can be removed

nothing (including oil, water, etc) remains in
the holes (see illustration).
25BMW recommend head bolts are renewed,
but if the old ones are re-used, mount each bolt
in a vice, and run a die down the threads to
remove corrosion and restore the threads. Dirt,
corrosion, sealant and damaged threads will
affect torque readings (see illustration). If the
bolts or their threads are damaged, do not re-
use the bolts - fit a new set.
26Refit any components removed from the
head prior to cleaning and inspection. On the
M40 engine, locate a new rubber O-ring in the
groove in the top of the oil pump/front end
cover housing (see illustration).
27Make sure the gasket sealing surfaces ofthe engine block and cylinder head are clean
and oil-free. Lay the head gasket in place on
the block, with the manufacturer’s stamped
mark facing up (it usually says “UP,” “OBEN”
or something similar). Use the dowel pins in the
top of the block to properly locate the gasket.
28Carefully set the cylinder head in place
on the block. Use the dowel pins to properly
align it. Where the engine is tilted slightly (ie
M40 engine) you may find it helpful to fit
guide studs to ensure correct positioning of
the cylinder head on the block. Use two old
head bolts, one screwed into each end of
the block. Cut the heads off the bolts, and
use a hacksaw to cut slots in the tops
of the bolts so they can be removed oncethe cylinder head is in position (see
illustration).
29Fit the cylinder head bolts (see
illustration).
30Tighten the cylinder head bolts, in the
sequence shown, to the torque listed in this
Chapter’s Specifications (see illustrations).
Note that on some engines the final stage of
tightening takes place after the engine has
been run.
31The remainder of refitting is the reverse of
removal. Set the valve clearances on M10,
M20 and M30 engines (see Chapter 1) before
refitting the valve cover (check them again
after the engine is warmed-up). Run the
engine and check for leaks.
2A•14 In-car engine repair procedures
12.30d Cylinder head bolt TIGHTENING
sequence for M40 (four-cylinder) engines12.30c Cylinder head bolt TIGHTENING
sequence for M30 (six-cylinder) engines12.30b Cylinder head bolt TIGHTENING
sequence for M20 (six-cylinder) engines
12.30a Cylinder head bolt TIGHTENING
sequence for M10 (four-cylinder) engines12.29 Inserting a cylinder head bolt
(M40 engine)12.28 Lowering the cylinder head onto the
block (M40 engine)
12.26 Fitting a new rubber O-ring in the
groove in the top of the oil pump/front end
cover on the M40 engine12.25 A die should be used to remove
sealant and corrosion from the head bolt
threads prior to installation12.24 The cylinder head bolt holes should
be cleaned and restored with a tap (be
sure to remove debris from the holes after
this is done)

13 Sump- removal and refitting
1
1Drain the engine oil (see Chapter 1).
2Raise the front of the vehicle and place it
securely on axle stands.
3Remove the splash shields from under the
engine.
4Where applicable, disconnect the hoses
attached to the sump, and move them to one
side (see illustration).
5Where applicable, disconnect the oil level
sensor electrical connector (see illustration).
6Where applicable, remove the cast-
aluminium inspection cover that covers the
rear of the sump (see illustrations).
7On models with the M40 engine, unbolt and
remove the lower sump section and remove
the gasket (this is necessary for access to the
front mounting bolts). Unscrew the mounting
bolt, and pull the oil dipstick tube from the
sump (see illustrations). Check the condition
of the O-ring, and renew it if necessary.
8On models with the M40 engine, unscrew
the engine mounting nuts on both sides, then
attach a suitable hoist and lift the engine
sufficiently to allow the sump to be removed.
As a safety precaution, position axle stands or
blocks of wood beneath the engine.
9Remove the bolts securing the sump to theengine block and front/rear covers (see
illustration).
10Tap on the sump with a soft-faced
hammer to break the gasket seal, and lower
the sump from the engine.
11Using a gasket scraper, scrape off all
traces of the old gasket from the engine
block, the timing chain cover, the rear main oil
seal housing, and the sump. Be especially
careful not to nick or gouge the gasket sealing
surfaces of the timing chain cover and the oil
seal housing (they are made of aluminium,
and are quite soft).
12Clean the sump with solvent, and dry it
thoroughly. Check the gasket sealing surfaces
for distortion. Clean any residue from thegasket sealing surfaces on the sump and
engine with a rag dampened with a suitable
solvent.
13Before refitting the sump, apply a little
RTV-type gasket sealant to the area where the
front and rear covers join the cylinder block..
Lay a new sump gasket in place on the block.
If necessary, apply more sealant to hold the
gasket in place.
14Carefully position the sump in place (do
not disturb the gasket) and refit the bolts.
Start with the bolts closest to the centre of the
sump, and tighten them to the torque listed in
this Chapter’s Specifications, using a criss-
cross pattern. Do not overtighten them, or
leakage may occur.
In-car engine repair procedures 2A•15
13.5 If applicable, disconnect the oil level
sensor connector at the left side of the
engine, down near the power steering
pump mounting bracket13.4 If applicable, remove the nut securing
the power steering lines to the sump, and
move the lines to one side to allow you to
get at the sump bolts12.30e Angle-tightening the cylinder head
bolts (M40 engine)
13.9 Remove the bolts holding the sump
to the engine block and front cover, as
shown here on a six-cylinder engine13.7b Removing the oil dipstick tube
bracket mounting bolt
13.6b . . . remove the cover to get to all
the sump bolts13.6a Remove the four inspection cover
bolts (arrowed) and . . .
13.7a Main sump retaining bolts accessed
after removal of the lower sump section on
the M40 engine (engine on bench for clarity)
2A

26Refit the cover plate and tighten the bolts
to the specified torque.
27To check the pressure relief valve, extract
the circlip and remove the sleeve, spring and
piston. Check that the length of the spring is
as given in the Specifications (see
illustrations). Reassemble the pressure relief
valve using a reversal of the dismantling
procedure.
Refitting
M10, M20 and M30 engines
28Make sure the mounting surfaces are
clean, then insert the pump into the engine
block recess. Refit the bolts and tighten them
to the torque specified at the beginning of this
Chapter.
29Refitting is the reverse of removal.
M40 engines
30Clean the mating surfaces, then refit the
front end cover and oil pump to the cylinder
block, together with a new gasket (see
illustration). Tighten the bolts to the
specified torque. Note that there are two sizes
of bolts, and they have different torque
settings.
31Fit the spacer ring on the front of the
crankshaft.
32Apply engine oil to the lips of the new oil
seal, then press it into the housing to its
previously-noted position. To ensure the oil
seal enters the housing squarely, use a large
socket and the crankshaft pulley bolt to pull it
into position (see illustration).
33Refit the key to the groove in the nose of
the crankshaft.34Refit the stabilising roller to the front end
cover, and tighten the bolt.
35Refit the sprocket, spacer and crankshaft
pulley bolt. Tighten the bolt to the specified
torque while holding the crankshaft stationary
using one of the methods previously
described.
36Refit the timing belt tensioning roller, but
do not tighten the bolt at this stage.
37Refit the cylinder head as described in
Section 12.
38Refit the timing belt as described in
Section 10.
39Refit the sump (see Section 13).
15 Flywheel/driveplate-
removal and refitting
3
1Remove the transmission (on vehicles with
manual transmission, see Chapter 7A; on
vehicles with automatic transmission, see
Chapter 7B).
2On vehicles with manual transmission,
remove the clutch (see Chapter 8).
3Where necessary, mark the relationship of
the flywheel/driveplate to the crankshaft, so it
can be refitted the same way.
4The flywheel/driveplate is attached to the
rear of the crankshaft with eight bolts. Loosen
and remove the bolts, then separate it from
2A•18 In-car engine repair procedures
14.32 Using a large socket and the
crankshaft pulley bolt to pull the oil seal
into the housing (M40 engine)14.30 Locating a new gasket on the front
of the cylinder block (M40 engine)14.27e Checking the length of the
pressure relief valve spring (M40 engine)
14.27d . . . and piston14.27c . . . spring . . .
14.27b . . . and remove the sleeve . . .14.27a Extract the circlip from the oil
pump (M40 engine) . . .14.24b Measuring the clearance between
the oil pump outer and inner rotors
(M40 engine)

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

4Check the mountings to see if the rubber is
cracked (see illustration), hardened or
separated from the metal plates. Sometimes
the rubber will split right down the centre.
5Check for relative movement between the
mounting plates and the engine or frame (use
a large screwdriver or lever to attempt to
move the mountings). If movement is noted,
lower the engine and tighten the mounting
nuts or bolts (see illustration). Rubber
preservative should be applied to the
mountings, to slow deterioration.
6On models with the M40 engine, check the
condition of the dampers on each mounting
by disconnecting them and attempting tocompress and expand them (see illustration).
If there is very little resistance to movement,
the dampers should be renewed.
Renewal
7If the dampers on the M40 engine are to be
renewed, simply unscrew the bolts, then fit
the new dampers and tighten the bolts.
8To renew the mountings, disconnect the
battery negative cable, then raise the vehicle
and support it securely on axle stands if you
haven’t already done so.
Caution: If the radio in your
vehicle is equipped with an anti-
theft system, make sure you
have the correct activation codebefore 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.
9Support the engine as described in
paragraph 3.
10Remove the large bracket-to-mounting
nut (see illustration). Raise the engine
slightly, then remove the lower mounting-to-
frame bolts/nuts and detach the mounting
11Refitting of the mountings is the reverse of
removal. Use thread-locking compound on
the mounting bolts/nuts, and be sure to
tighten them securely.
2A•20 In-car engine repair procedures
17.10 To remove an engine mounting, first
remove the stud nut (arrowed) -
M30 engine shown, others similar17.6 Engine mounting and damper on the
M40 engine17.5 Lever gently between the block and
the engine mounting attachment point
(arrowed) - if there is movement, tighten
the bolts

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

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)