Fuel BMW 3 SERIES 1983 E30 User Guide

stripes moulded into them. Various systems
require hoses with different wall thicknesses,
collapse resistance and temperature
resistance. When fitting new hoses, be sure
the new ones are made of the same material.
5Often the only effective way to check a
hose is to remove it completely from the
vehicle. If more than one hose is removed, be
sure to label the hoses and fittings to ensure
correct refitting.
6When checking vacuum hoses, be sure to
include any plastic T-fittings in the check.
Inspect the connections for cracks which
could cause leakage.
7A small piece of vacuum hose can be used
as a stethoscope to detect vacuum leaks.
Hold one end of the hose to your ear and
probe around vacuum hoses and fittings,
listening for the “hissing” sound characteristic
of a vacuum leak.
Warning: When probing with the
vacuum hose stethoscope, be
careful not to touch moving
engine components such as the
drivebelt, cooling fan, etc.
Fuel hoses
Warning: There are certain
precautions which must be taken
when servicing or inspecting fuel
system components. Work in a
well-ventilated area, and do not allow open
flames (cigarettes, appliance pilot lights,
etc.) or bare light bulbs near the work
area. Mop up any spills immediately, and
do not store fuel-soaked rags where they
could ignite. 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.
8The fuel hoses are usually under pressure,
so if any fuel hoses are to be disconnected,
be prepared to catch spilled fuel.
Warning: On vehicles equipped
with fuel injection, you must
depressurise the fuel system
before servicing the fuel hoses.
Refer to Chapter 4 for details.9Check all rubber fuel hoses for deterioration
and chafing. Check especially for cracks in
areas where the hose bends, and just before
connectors, such as where a hose attaches to
the fuel pump or fuel filter, for example.
10Only high-quality fuel hose should be
used. Never, under any circumstances, use
unreinforced vacuum hose, clear plastic
tubing or water hose for fuel hoses.
11Band-type clamps are commonly used on
fuel hoses. These clamps often lose their
tension over a period of time, and can be
“sprung” during removal. Renew all band-type
clamps with screw clamps whenever a hose is
renewed.
Metal lines
12Sections of metal line are often used
between the fuel pump and fuel injection
system. Check carefully to make sure the line
isn’t bent, crimped or cracked.
13If a section of metal line must be renewed,
use seamless steel tubing only, since copper
and aluminium tubing do not have the
strength necessary to withstand the vibration
caused by the engine.
14Check the metal brake lines where they
enter the master cylinder and brake
proportioning or ABS unit (if used) for cracks
in the lines and loose fittings. Any sign of
brake fluid leakage calls for an immediate
thorough inspection of the braking system.
Power steering hoses
15Check the power steering hoses for leaks,
loose connections and worn clamps. Tighten
loose connections. Worn clamps or leaky
hoses should be renewed.
11 Drivebelt check, adjustment
and renewal
1
Check
1The drivebelts, sometimes called V-belts or
simply “fan” belts, are located at the front of
the engine, and play an important role in the
overall operation of the vehicle and itscomponents. Due to their function and
material make-up, the belts are prone to
failure after a period of time, and should be
inspected and adjusted periodically to prevent
major engine damage.
2The number of belts used on a particular
vehicle depends on the accessories fitted.
Drivebelts are used to turn the alternator,
power steering pump, water pump, and air
conditioning compressor. Depending on the
pulley arrangement, a single belt may be used
to drive more than one of these components.
3With the engine switched off, open the
bonnet and locate the various belts at the
front of the engine. Using your fingers (and a
torch, if necessary), move along the belts,
checking for cracks and separation of the belt
plies. Also check for fraying and glazing,
which gives the belt a shiny appearance (see
illustration). Both sides of the belts should be
inspected, which means you will have to twist
each belt to check the underside.
4The tension of each belt is checked by
pushing firmly with your thumb and seeing
how much the belt moves (deflects). Measure
the deflection with a ruler (see illustration). A
good rule of thumb is that the belt should
deflect 6 mm if the distance from pulley
centre-to-pulley centre is between 180 and
280 mm. The belt should deflect 13 mm if the
distance from pulley centre-to-pulley centre is
between 300 and 400 mm.
Adjustment
5If it is necessary to adjust the belt tension,
either to make the belt tighter or looser, it is
done by moving a belt-driven accessory on its
bracket. (When the same belt drives more
than one accessory, normally only one
accessory is moved when making
adjustment.)
6For each component, there will be an
adjusting bolt and a pivot bolt. Both bolts
must be loosened slightly to enable you to
move the component. On some components,
the drivebelt tension can be adjusted by
turning an adjusting bolt after loosening the
lockbolt (see illustration).
7After the two bolts have been loosened,
1•14
11.6 Loosen the nut on the other end of
the adjuster bolt (arrowed) and turn the
bolt to increase or decrease tension on the
drivebelt11.4 Measuring drivebelt deflection with a
straightedge and ruler11.3 Here are some of the more common
problems associated with drivebelts
(check the belts very carefully to prevent
an untimely breakdown)
Every 6000 miles

drag when the feeler gauge is moved back
and forth.
6If the gap is too large or too small, loosen
the locknut, insert a hook made from large-
diameter metal wire, and rotate the eccentric
to obtain the correct gap (see illustration).
7Once the gap has been set, hold the
eccentric in position with the hook, and
retighten the locknut securely. Recheck the
clearance - sometimes it’ll change slightly
when the locknut is tightened. If so, re-adjust
until it’s correct.
8On the M10 engine, the valves are adjusted
in the firing order, which is 1-3-4-2. After
adjusting No 1 cylinder valves, rotate the
crankshaft half a turn (180º), then check and
adjust the valves on No 3 cylinder. Repeat the
procedure on the remaining cylinders.
9On M20 and M30 engines, the valves are
adjusted following the firing order, which is
1-5-3-6-2-4. After adjusting No 1 cylinder
valves, rotate the crankshaft a third of a turn
(120º), then check and adjust the valves on No
5 cylinder. Repeat the procedure for the
remaining cylinders.
10Refit the valve cover (use a new gasket)
and tighten the mounting nuts evenly and
securely.
11Start the engine and check for oil leakage
between the valve cover and the cylinder
head.19 Throttle linkage -
check and lubrication
1
1The throttle linkage should be checked and
lubricated periodically to ensure its proper
operation.
2Check the linkage to make sure it isn’t
binding.
3Inspect the linkage joints for looseness, and
the connections for corrosion and damage,
renewing parts as necessary (see
illustration).
4Lubricate the connections with spray
lubricant or lithium-based grease.
20 Air filter renewal
1
Carburettor engines
1Release the spring clips, then unscrew the
centre nut and lift off the cover.
2Remove the air filter element, and wipe
clean the air cleaner body and cover
3Fit the new air filter element, then refit the
cover using a reversal of the removal
procedure.
Fuel injection engines
4Loosen the clamp on the air intake duct,
and detach the duct (see illustration).5Release the air cleaner cover retaining clips
(see illustration).
6Rotate the cover up, lift it off and lift the
element out, noting which way round it is
fitted (see illustrations).
7Wipe the inside of the air cleaner housing
with a clean cloth, then fit the new element. If
the element is marked TOP, be sure the
marked side faces up.
8Refit the cover and secure the clips.
9Connect the air duct and tighten the clamp
screw.
21 Fuel system check
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. Work in a well-
ventilated area. 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. Mop
up spills immediately, but do not store
fuel-soaked rags where they could ignite.
1If you smell fuel while driving or after the
vehicle has been sitting in the sun, inspect the
fuel system immediately.
2Remove the fuel filler cap and inspect it for
damage and corrosion. The gasket should
have an unbroken sealing imprint. If the
gasket is damaged or corroded, fit a new cap.
3Inspect the fuel feed and return lines for
cracks. Make sure that the connections
between the fuel lines and the carburettor or
fuel injection system, and between the fuel
lines and the in-line fuel filter, are tight.
Warning: On fuel injection
models, the fuel system must be
depressurised before servicing
fuel system components, as
outlined in Chapter 4.
1•20
20.6b . . . and lift the air filter
element out20.6a Rotate the cover
upwards . . .
20.5 Use a screwdriver to detach the air
cleaner cover clips20.4 Detach the duct from the air cleaner
housing19.3 Check and lubricate the throttle
linkage at the points shown (arrowed) -
fuel injection engine shown
Every 12 000 miles

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

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

1 General information
This Part of Chapter 2 is devoted to in-
vehicle engine repair procedures. All
information concerning engine removal and
refitting and engine block and cylinder head
overhaul can be found in Chapter 2B.
The following repair procedures are based
on the assumption that the engine is still fitted
in the vehicle. If the engine has been removed
from the vehicle and mounted on a stand,
many of the steps outlined in this Part of
Chapter 2 will not apply.
The Specifications included in this Part of
Chapter 2 apply only to the procedures
contained in this Part. Chapter 2B contains
the Specifications necessary for cylinder head
and engine block rebuilding.
The single overhead camshaft four- and
six-cylinder engines covered in this manual
are very similar in design. Where there are
differences, they will be pointed out.
The means by which the overhead
camshaft is driven varies according to engine
type; M10 and M30 engines use a timing
chain, while M20 and M40 engines have a
timing belt.
2 Repair operations possible
with the engine in the vehicle
Many major repair operations can be
accomplished without removing the engine
from the vehicle.
Clean the engine compartment and the
exterior of the engine with some type of
degreaser before any work is done. It will
make the job easier, and help keep dirt out of
the internal areas of the engine.
Depending on the components involved, it
may be helpful to remove the bonnet to
improve access to the engine as repairs are
performed (see Chapter 11 if necessary).
Cover the wings to prevent damage to the
paint. Special pads are available, but an old
bedspread or blanket will also work.
If vacuum, exhaust, oil or coolant leaks
develop, indicating a need for gasket or seal
renewal, the repairs can generally be made
with the engine in the vehicle. The intake and
exhaust manifold gaskets, sump gasket,
crankshaft oil seals and cylinder head gasket
are all accessible with the engine in place.
Exterior components, such as the intake
and exhaust manifolds, the sump, the oil
pump, the water pump, the starter motor, the
alternator, the distributor and the fuel system
components, can be removed for repair with
the engine in place.
The cylinder head can be removed without
removing the engine, so this procedure is
covered in this Part of Chapter 2. Camshaft,
rocker arm and valve component servicing ismost easily accomplished with the cylinder
head removed; these procedures are covered
in Part B of this Chapter. Note, however, that
the camshaft on the M40 engine may be
removed with the engine in the vehicle since it
is retained by bearing caps.
In extreme cases caused by a lack of
necessary equipment, repair or renewal of
piston rings, pistons, connecting rods and
big-end bearings is possible with the engine in
the vehicle. However, this practice is not
recommended, because of the cleaning and
preparation work that must be done to the
components involved.
3 Top Dead Centre (TDC) for
No 1 piston- locating
2
Note 1:The following procedure is based on
the assumption that the distributor (if
applicable) is correctly fitted. If you are trying
to locate TDC to refit the distributor correctly,
piston position must be determined by feeling
for compression at the No 1 spark plug hole,
then aligning the ignition timing marks or
inserting the timing tool in the flywheel, as
applicable.
Note 2:The No 1 cylinder is the one closest to
the radiator.
1Top Dead Centre (TDC) is the highest point
in the cylinder that each piston reaches as it
travels up and down when the crankshaft
turns. Each piston reaches TDC on the
compression stroke and again on the exhaust
stroke, but TDC generally refers to piston
position on the compression stroke.
2Positioning the piston at TDC is an essential
part of many procedures, such as timing belt
or chain removal and distributor removal.
3Before beginning this procedure, be sure to
place the transmission in Neutral, and apply
the handbrake or chock the rear wheels. Also,
disable the ignition system by detaching the
coil wire from the centre terminal of the
distributor cap, and earthing it on the engine
block with a jumper wire. Remove the spark
plugs (see Chapter 1).
4In order to bring any piston to TDC, the
crankshaft must be turned using one of the
methods outlined below. When looking at the
front of the engine, normal crankshaft rotation
is clockwise.
(a) The preferred method is to turn the
crankshaft with a socket and ratchet
attached to the bolt threaded into the
front of the crankshaft.
(b) A remote starter switch, which may save
some time, can also be used. Follow the
instructions included with the switch.
Once the piston is close to TDC, use a
socket and ratchet as described in the
previous paragraph.
(c) If an assistant is available to turn the
ignition switch to the Start position in
short bursts, you can get the piston close
to TDC without a remote starter switch.Make sure your assistant is out of the
vehicle, away from the ignition switch,
then use a socket and ratchet as
described in (a) to complete the
procedure.
5Note the position of the terminal for the
No 1 spark plug lead on the distributor cap. If
the terminal isn’t marked, follow the plug lead
from the No 1 cylinder spark plug to the cap
(No 1 cylinder is nearest the radiator).
6Use a felt-tip pen or chalk to make a mark
directly below the No 1 terminal on the
distributor body or timing cover.
7Detach the distributor cap, and set it aside
(see Chapter 1 if necessary).
8Turn the crankshaft (see paragraph 4
above) until the timing marks (located at the
front of the engine) are aligned (see
illustration). The M40 engine does not have
any timing marks at the front of the engine,
but instead has a timing hole in the flywheel
which must be aligned with a hole in the rear
flange of the cylinder block. On this engine,
turn the crankshaft until the distributor rotor is
approaching the No 1 TDC position, then
continue to turn the crankshaft until a suitable
close-fitting drill can be inserted through the
hole in the cylinder block and into the
flywheel.
9Look at the distributor rotor - it should be
pointing directly at the mark you made on the
distributor body or timing cover.
10If the rotor is 180 degrees out, the No 1
piston is at TDC on the exhaust stroke.
11To get the piston to TDC on the
compression stroke, turn the crankshaft one
complete turn (360°) clockwise. The rotor
should now be pointing at the mark on the
distributor or timing cover. When the rotor is
pointing at the No 1 spark plug lead terminal
in the distributor cap and the ignition timing
marks are aligned, the No 1 piston is at TDC
on the compression stroke. Note:If it’s
impossible to align the ignition timing marks
when the rotor is pointing at the mark, the
timing belt or chain may have jumped the
teeth on the sprockets, or may have been
fitted incorrectly.
In-car engine repair procedures 2A•3
3.8 Align the notch in the pulley with the
notch on the timing plate, then check to
see if the distributor rotor is pointing to the
No 1 cylinder (if not, the camshaft is 180
degrees out - the crankshaft will have to
be rotated 360 degrees)
2A

12After the No 1 piston has been positioned
at TDC on the compression stroke, TDC for
any of the remaining pistons can be located
by turning the crankshaft and following the
firing order. Mark the remaining spark plug
lead terminal locations just like you did for the
No 1 terminal, then number the marks to
correspond with the cylinder numbers. As you
turn the crankshaft, the rotor will also turn.
When it’s pointing directly at one of the marks
on the distributor, the piston for that particular
cylinder is at TDC on the compression stroke.
4 Valve cover-
removal and refitting
1
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.
Removal
1Disconnect the battery negative cable.
2Detach the breather hose from the valve
cover.
3On M20 engines, unbolt and remove the
intake manifold support bracket and, if
applicable, the bracket for the engine sensors
or idle air stabiliser (it will probably be
necessary to disconnect the electrical
connectors from the sensors and stabiliser).
4On M30 engines, disconnect the electrical
connector for the airflow sensor. Unclip the
electrical harness, moving it out of the way.
5Where necessary on M30 engines, remove
the hoses and fittings from the intake air hose,
then loosen the clamp and separate the hose
from the throttle body. Unscrew the mounting
nuts for the air cleaner housing, and remove
the housing together with the air hose and
airflow sensor.
6Remove the valve cover retaining nuts and
washers (see illustrations). Where necessary,
disconnect the spark plug lead clip or coverfrom the stud(s), and set it aside. It will usually
not be necessary to disconnect the leads from
the spark plugs.
7Remove the valve cover and gasket.
Discard the old gasket. On the M40 engine,
also remove the camshaft cover (see
illustrations). If applicable, remove the semi-
circular rubber seal from the cut-out at the
front of the cylinder head.
Refitting
8Using a scraper, remove all traces of old
gasket material from the sealing surfaces of
the valve cover and cylinder head.
Caution: Be very careful not to
scratch or gouge the delicate
aluminium surfaces. Gasket
removal solvents are available at
motor factors, and may prove helpful.
After all gasket material has been
removed, the gasket surfaces can be
degreased by wiping them with a rag
dampened with a suitable solvent.
9If applicable, place a new semi-circular
rubber seal in the cut-out at the front of the
cylinder head, then apply RTV-type gasket
sealant to the joints between the seal and the
mating surface for the valve cover gasket.
Note:After the sealant is applied, you should
refit the valve cover and tighten the nuts within
ten minutes.
10Refit the camshaft cover (M40 engine), the
valve cover and a new gasket. Refit the
washers and nuts; tighten the nuts evenly and
securely. Don’t overtighten these nuts - theyshould be tight enough to prevent oil from
leaking past the gasket, but not so tight that
they warp the valve cover.
11The remainder of refitting is the reverse of
removal.
5 Intake manifold-
removal and refitting
2
Removal
1Allow the engine to cool completely, then
relieve the fuel pressure on fuel-injection
engines (see Chapter 4).
2Disconnect the battery negative cable.
Caution: If the radio in your
vehicle is equipped with an anti-
theft system, make sure you
have the correct activation code
before disconnecting the battery.
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.
3Drain the engine coolant (see Chapter 1)
below the level of the intake manifold. If the
coolant is in good condition, it can be saved
and reused.
4On fuel injection engines, loosen the hose
clamp and disconnect the large air inlet hose
from the throttle body. It may also be
necessary to remove the entire air
cleaner/inlet hose assembly to provide
enough working room (see Chapter 4).
2A•4 In-car engine repair procedures
4.7b Removing the camshaft cover on the
M40 engine4.7a Removing the valve cover on the
M40 engine4.7c Removing the valve cover gasket on
the M40 engine
4.6b Valve cover bolt locations (arrowed)
on M20 six-cylinder engines4.6a Valve cover bolt locations (arrowed)
on M10 four-cylinder engines

5On carburettor engines, remove the
complete air cleaner assembly (see Chap-
ter 4).
6Disconnect the coolant hoses from the
throttle body/intake manifold as applicable.
7Disconnect the throttle cable and, if
applicable, cruise control cable (see Chap-
ter 4).
8Remove the EGR valve and line where
applicable (see Chapter 6).
9At this stage on the M40 engine, the upper
part of the intake manifold should be removed
by unscrewing the bolts and nuts. Remove
the gaskets (see illustrations).
10On fuel injection engines, disconnect the
vacuum hose from the fuel pressure regulator,
and disconnect the electrical connectors from
the fuel injectors (see Chapter 4).
11Disconnect the fuel lines from the fuel rail
or carburettor, as applicable (see Chapter 4).
12On the M40 engine, unbolt and remove
the support bracket from the bottom of the
intake manifold (see illustration).
13Disconnect all remaining hoses and wires
attached between the intake manifold/throttle
body assembly and the engine or chassis.
14Remove the bolts and/or nuts that attach
the manifold to the cylinder head (see
illustrations). Start at the ends and work
toward the middle, loosening each one a little
at a time until they can be removed by hand.
Support the manifold while removing the
fasteners so it doesn’t fall. Note: You can
remove the manifold without removing the
throttle body, injectors, vacuum/thermovalves, fuel pressure regulator or carburettor.
If you’re fitting a new manifold, transfer the
components (see Chapter 4) and lines to the
new manifold before it is fitted on the cylinder
head.
15Move the manifold up and down to break
the gasket seal, then lift it away from the head
and remove the gasket (see illustrations).
Refitting
16Remove the old gasket, then carefully
scrape all traces of sealant off the head and
the manifold mating surfaces. Be very careful
not to nick or scratch the delicate aluminium
mating surfaces. Gasket removal solvents are
available at motor factors, and may prove
helpful. Make sure the surfaces are perfectly
clean and free of dirt and oil.17Check the manifold for corrosion (at the
coolant passages), cracks, warping and other
damage. Cracks and warping normally show
up near the gasket surface, around the stud
holes. If defects are found, have the manifold
repaired (or renew it, as necessary).
18When refitting the manifold, always use a
new gasket. Where one side of the gasket has
a graphite surface, this must face the cylinder
head.
19Refit the nuts and bolts and tighten them
gradually, working from the centre out to the
ends, to the torque listed in this Chapter’s
Specifications.
20The remainder of refitting is the reverse of
removal. On the M40 engine, renew the
gaskets between the upper and lower parts of
the manifold.
In-car engine repair procedures 2A•5
5.9c . . . and gaskets5.9b . . . and remove the upper part of the
intake manifold . . .5.9a On the M40 engine, remove the nuts
and special bolts . . .
5.15b Removing the lower intake manifold
gasket (M40 engine)5.15a Removing the lower intake manifold
(M40 engine)
5.14a Remove the intake manifold nuts
with a socket, ratchet and long extension
(M20 engine)5.12 Removing the support bracket from
the bottom of the intake manifold
(M40 engine)
5.14b Removing the lower intake manifold
nuts (M40 engine)
2A

6 Exhaust manifold-
removal and refitting
1
Warning: Make sure the engine is
completely cool before beginning
work on the exhaust system.
Caution: If the radio in your
vehicle is equipped with an anti-
theft system, make sure you
have the correct activation code
before disconnecting the battery.
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.
1Disconnect the battery negative cable.
2On models where the air cleaner is on the
exhaust manifold side of the engine, remove
the air cleaner housing assembly and/or
airflow sensor to provide sufficient working
area (see Chapter 4, if necessary).
3Unplug the HT leads and set the spark plug
lead harness aside (see Chapter 1).
4Clearly label, then disconnect or remove, all
wires, hoses, fittings, etc. that are in the way.
Be sure to disconnect the oxygen sensor,
where fitted.
5Raise the vehicle, and support it securely
on axle stands. Working from under the
vehicle, separate the exhaust downpipe from
the manifold. Use penetrating oil on the
fasteners to ease removal (see illustrations).
6Remove the axle stands, and lower the
vehicle. Working from the ends of the
manifold toward the centre, loosen the
retaining nuts gradually until they can be
removed. Again, penetrating oil may prove
helpful.
7Pull the manifold off the head, then remove
the old gaskets (see illustrations). Note:Be
very careful not to damage the oxygen sensor,
where fitted.8Clean the gasket mating surfaces of the
head and manifold, and make sure the
threads on the exhaust manifold studs are in
good condition.
9Check for corrosion, warping, cracks, and
other damage. Repair or renew the manifold
as necessary.
10When refitting the manifold, use new
gaskets. Tighten the manifold-to-head
retaining nuts gradually, starting at the centre
and working out to the ends, to the torque
listed in this Chapter’s Specifications. Also
tighten the downpipe-to-manifold nuts.
11The remaining steps are simply a reversal
of the removal procedure.
7 Timing chain covers-
removal and refitting
5
Note 1:This procedure applies to M10 and
M30 engines.
Note 2:The upper timing chain cover can be
removed separately. If you need to remove
both the upper and lower covers, special tools
are required. Read paragraphs 8 and 9 before
beginning work.
Removal
1Disconnect the battery negative cable.Caution: If the radio in your
vehicle is equipped with an anti-
theft system, make sure you
have the correct activation code before
disconnecting the battery.
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.
2If you’re removing the lower timing chain
cover (the upper cover can be removed
separately), remove the cooling fan and fan
shroud, the radiator and the fan drivebelt
pulley (see Chapter 3).
3On the M10 engine only, remove the water
pump (see Chapter 3).
4On engines where the distributor cap is
mounted directly to the timing chain cover,
remove the cap, rotor and the black plastic
cover beneath the rotor (see Chapter 1).
5On the M30 engine fitted with the
L-Jetronic fuel system, remove the
distributor from the upper timing cover (see
Chapter 5).
6Remove the valve cover (see Section 4).
7If you’ll be removing the lower timing chain
cover on the M30 engine, remove the crankshaft
pulley from the vibration damper/hub. Hold the
pulley stationary with a socket on the centre
bolt, and remove the pulley bolts with another
socket (see illustration).
8If you’ll be removing the lower timing chain
2A•6 In-car engine repair procedures
6.7c Removing the exhaust manifold-to-
downpipe gasket (M40 engine)6.7b Removing the exhaust manifold
gasket (M40 engine)6.7a Removing the exhaust manifold
(M40 engine)
6.5b Exhaust manifold-to-downpipe flange
(M40 engine)6.5a Remove the exhaust manifold nuts
(arrowed) from the exhaust pipe (M20
engine) - soaking the nuts with penetrating
oil should make them easier to remove
Remove the windscreen
washer reservoir from the
right-hand side of the engine
compartment to give more
working room.

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