1990 BMW 5 SERIES warning light

4Since some components of the fuel system
- the fuel tank and some of the fuel feed and
return lines, for example - are underneath the
vehicle, they can be inspected more easily
with the vehicle raised on a hoist. If that’s not
possible, raise the vehicle and support it on
axle stands or ramps.
5With the vehicle raised and safely
supported, inspect the fuel tank and filler neck
for punctures, cracks or other damage. The
connection between the filler neck and the
tank is particularly critical. Sometimes a
rubber filler neck will leak because of loose
clamps or deteriorated rubber. Inspect all fuel
tank mounting brackets and straps, to be sure
the tank is securely attached to the vehicle.
Warning: Do not, under any
circumstances, try to repair a fuel
tank (except rubber
components). A welding torch or
any naked flame can easily cause fuel
vapours inside the tank to explode.
6Carefully check all flexible hoses and metal
lines leading away from the fuel tank. Check
for loose connections, deteriorated hoses,
crimped lines, and other damage. Repair or
renew damaged sections as necessary (see
Chapter 4).
22 Cooling system check
1
1Many major engine failures can be
attributed to cooling system problems. If the
vehicle has automatic transmission, the
engine cooling system also plays an importantrole in prolonging transmission life, because it
cools the transmission fluid.
2The engine should be cold for the cooling
system check, so perform the following
procedure before the vehicle is driven for the
day, or after it has been switched off for at
leastthree hours.
3Remove the radiator cap, doing so slowly
and taking adequate precautions against
scalding if the engine is at all warm. Clean the
cap thoroughly, inside and out, with clean
water. Also clean the filler neck on the
radiator. The presence of rust or corrosion in
the filler neck means the coolant should be
changed (see Section 29). The coolant inside
the radiator should be relatively clean and
clear. If it’s rust-coloured, drain the system
and refill with new coolant.
4Carefully check the radiator hoses and the
smaller-diameter heater hoses. Inspect each
coolant hose along its entire length, renewing
any hose which is cracked, swollen or
deteriorated (see illustration). Cracks will
show up better if the hose is squeezed. Pay
close attention to hose clamps that secure the
hoses to cooling system components. Hose
clamps can pinch and puncture hoses,
resulting in coolant leaks.
5Make sure all hose connections are tight. A
leak in the cooling system will usually show up
as white or rust-coloured deposits on the area
adjoining the leak. If wire-type clamps are
used on the hoses, it may be a good idea to
replace them with screw-type clamps.
6Clean the front of the radiator (and, where
applicable, the air conditioning condenser)
with compressed air if available, or a soft
brush. Remove all flies, leaves, etc,
embedded in the radiator fins. Be extremely
careful not to damage the cooling fins or to
cut your fingers on them.
7If the coolant level has been dropping
consistently and no leaks are detected, have
the radiator cap and cooling system pressure-
tested.
23 Exhaust system check
1
1The engine should be cold for this check,
so perform the following procedure before the
vehicle is driven for the day, or after it has
been switched off for at leastthree hours.
Check the complete exhaust system from the
engine to the end of the tailpipe. Ideally, the
inspection should be done with the vehicle on
a hoist, to give unrestricted access. If a hoist
isn’t available, raise the vehicle and support it
securely on axle stands or ramps.
2Check the exhaust pipes and connections
for evidence of leaks, severe corrosion, and
damage. Make sure that all brackets and
mountings are in good condition, and that
they are tight (see illustration).
3At the same time, inspect the underside of
the body for holes, corrosion, open seams,etc. which may allow exhaust gases to enter
the passenger compartment. Seal all body
openings with suitable sealant.
4Rattles and other noises can often be
traced to the exhaust system, especially the
mountings and heat shields. Try to move the
pipes, silencers (and, where applicable, the
catalytic converter). If the components can
come in contact with the body or suspension
parts, re-hang the exhaust system with new
mountings.
5The running condition of the engine may be
checked by inspecting inside the end of the
tailpipe. The exhaust deposits here are an
indication of the engine’s state of tune. If the
pipe is black and sooty, the engine may be
running too rich, indicating the need for a
thorough fuel system inspection.
24 Steering and suspension
check
1
Note: The steering linkage and suspension
components should be checked periodically.
Worn or damaged suspension and steering
linkage components can result in excessive
and abnormal tyre wear, poor ride quality and
vehicle handling, and reduced fuel economy.
For detailed illustrations of the steering and
suspension components, refer to Chapter 10.
Strut/shock absorber check
1Park the vehicle on level ground, turn the
engine off and apply the handbrake. Check
the tyre pressures.
2Push down at one corner of the vehicle,
then release it while noting the movement of
the body. It should stop moving and come to
rest in a level position with one or two
bounces.
3If the vehicle continues to move up and
down, or if it fails to return to its original
position, a worn or weak strut or shock
absorber is probably the reason.
4Repeat the above check at each of the
three remaining corners of the vehicle.
5Raise the vehicle and support it on axle
stands.
6Check the struts/shock absorbers for
evidence of fluid leakage. A light film of fluid is
1•21
22.4 Hoses, like drivebelts, have a habit of
failing at the worst possible time - to
prevent the inconvenience of a blown
radiator or heater hose, inspect them
carefully as shown here
23.2 Check the exhaust system rubber
mountings for cracks
1
Every 12 000 miles

no cause for concern. Make sure that any fluid
noted is from the struts/shocks, and not from
any other source. If leakage is noted, renew
the struts or shock absorbers in axle pairs (or
as a full set).
7Check the struts/shock absorbers to be
sure that they are securely mounted and
undamaged. Check the upper mountings for
damage and wear. If damage or wear is
noted, renew the struts or shock absorbers.
8If the struts or shock absorbers must be
renewed, refer to Chapter 10 for the
procedure. Always renew both units on the
same axle, or the safety of the vehicle may be
compromised. If possible, renew all four as a
set.
Steering and suspension check
9Inspect the steering system components
for damage and distortion. Look for leaks and
damaged seals, boots and fittings.
10Clean the lower end of the steering
knuckle. Have an assistant grasp the lower
edge of the tyre and move the wheel in and
out, while you look for movement at the
steering knuckle-to-axle arm balljoints.
Inspect the balljoint boots for tears (see
illustration). If there is any movement, or the
boots are torn or leaking, the balljoint(s) must
be renewed.
11Grasp each front tyre at the front and rear
edges, push in at the front, pull out at the rear
and feel for play in the steering linkage. If any
free play is noted, check the steering gear
mountings and the track rod balljoints for
looseness. If the steering gear mountings are
loose, tighten them. If the track rods are
loose, the balljoints may be worn (check to
make sure the nuts are tight). Additional
steering and suspension system information
can be found in Chapter 10.
25 Driveshaft gaiter check
1
1The driveshaft gaiters are very important
because they prevent dirt, water and foreign
material from entering and damaging the
constant velocity (CV) joints. External oil and
grease contamination can cause the gaitermaterial to deteriorate prematurely, so it’s a
good idea to wash the gaiters with soap and
water.
2Inspect the gaiters for tears and cracks, as
well as for loose clamps (see illustration). If
there is any evidence of cracks or leaking
lubricant, the gaiter must be renewed (see
Chapter 8).
26 Brake system check
2
Warning: Dust produced by lining
wear and deposited on brake
components may contain
asbestos, which is hazardous to
your health. Do not blow it out with
compressed air, and don’t inhale it! Do not
use petroleum-based solvents to remove
the dust. Brake system cleaner or
methylated spirit should be used to flush
the dust into a drain pan. After the brake
components are wiped with a damp rag,
dispose of the contaminated rag(s) and the
drain pan contents into a covered and
labelled container. Try to use asbestos-
free new parts whenever possible.
Note:In addition to the specified intervals, the
brake system should be inspected each time
the wheels are removed or a malfunction is
indicated. Because of the obvious safety con-
siderations, the following brake system checks
are some of the most important maintenance
procedures you can perform on your vehicle.
Symptoms of brake system
problems
1The disc brakes have built-in electrical wear
indicators which cause a warning light on the
dash to come on when they’re worn to the
renewal point. When the light comes on,
renew the pads immediately, or expensive
damage to the brake discs could result.
2Any of the following symptoms could
indicate a potential brake system defect:
a) Vehicle pulls to one side when the brake
pedal is depressed
b) Brakes make squealing or dragging noises
when applied
c) Brake pedal travel excessived) Brake pedal pulsates (normal if ABS is
working)
e) Brake fluid leaks (usually on the inner side
of the tyre or wheel)
3If any of these conditions are noted, inspect
the brake system immediately.
Brake lines and hoses
Note: Steel brake pipes are used throughout
the brake system, with the exception of
flexible, reinforced hoses at the front wheels
and as connectors at the rear axle. Periodic
inspection of all these lines is very important.
4Park the vehicle on level ground, and
switch off the engine. Remove the wheel
covers. Loosen, but do not remove, the bolts
on all four wheels.
5Raise the vehicle and support it securely on
axle stands.
6Remove the wheels (see “Jacking and
towing” at the front of this book, or refer to
your owner’s handbook, if necessary).
7Check all brake lines and hoses for cracks,
chafing of the outer cover, leaks, blisters, and
distortion. Check the brake hoses at front and
rear of the vehicle for softening, cracks,
bulging, or wear from rubbing on other
components. Check all threaded fittings for
leaks, and make sure the brake hose
mounting bolts and clips are secure.
8If leaks or damage are discovered, they
must be repaired immediately. Refer to
Chapter 9 for detailed brake system repair
procedures.
Disc brakes
9If it hasn’t already been done, raise the
vehicle and support it securely on axle stands.
Remove the front wheels.
10The disc brake calipers, containing the
pads, are now visible. Each caliper has an
outer and an inner pad - all pads should be
checked.
11Note the pad thickness by looking
through the inspection hole in the caliper (see
illustration). If the lining material is 2.0 mm
thick or less, or if it is tapered from end to
end, the pads should be renewed (see
Chapter 9). Keep in mind that the lining
1•22
26.11 Look through the caliper inspection
window to inspect the brake pads - the
pad lining which rubs against the disc can
also be inspected by looking through each
end of the caliper25.2 Gently probe the driveshaft boots to
check for cracks24.10 Inspect the balljoint boots for tears
(arrowed)
Every 12 000 miles

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)