Ignition BMW 3 SERIES 1985 E30 Workshop Manual

0•6Safety First!
Working on your car can be dangerous.
This page shows just some of the potential
risks and hazards, with the aim of creating a
safety-conscious attitude.
General hazards
Scalding
• Don’t remove the radiator or expansion
tank cap while the engine is hot.
• Engine oil, automatic transmission fluid or
power steering fluid may also be dangerously
hot if the engine has recently been running.
Burning
• Beware of burns from the exhaust system
and from any part of the engine. Brake discs
and drums can also be extremely hot
immediately after use.
Crushing
• When working under or near
a raised vehicle,
always
supplement the
jack with axle
stands, or use
drive-on
ramps.
Never
venture
under a car which
is only supported by a jack.
• Take care if loosening or tightening high-
torque nuts when the vehicle is on stands.
Initial loosening and final tightening should
be done with the wheels on the ground.
Fire
• Fuel is highly flammable; fuel vapour is
explosive.
• Don’t let fuel spill onto a hot engine.
• Do not smoke or allow naked lights
(including pilot lights) anywhere near a
vehicle being worked on. Also beware of
creating sparks
(electrically or by use of tools).
• Fuel vapour is heavier than air, so don’t
work on the fuel system with the vehicle over
an inspection pit.
• Another cause of fire is an electrical
overload or short-circuit. Take care when
repairing or modifying the vehicle wiring.
• Keep a fire extinguisher handy, of a type
suitable for use on fuel and electrical fires.
Electric shock
• Ignition HT
voltage can be
dangerous,
especially to
people with heart
problems or a
pacemaker. Don’t
work on or near the
ignition system with
the engine running or
the ignition switched on.• Mains voltage is also dangerous. Make
sure that any mains-operated equipment is
correctly earthed. Mains power points should
be protected by a residual current device
(RCD) circuit breaker.
Fume or gas intoxication
• Exhaust fumes are
poisonous; they often
contain carbon
monoxide, which is
rapidly fatal if inhaled.
Never run the
engine in a
confined space
such as a garage
with the doors shut.
• Fuel vapour is also
poisonous, as are the vapours from some
cleaning solvents and paint thinners.
Poisonous or irritant substances
• Avoid skin contact with battery acid and
with any fuel, fluid or lubricant, especially
antifreeze, brake hydraulic fluid and Diesel
fuel. Don’t syphon them by mouth. If such a
substance is swallowed or gets into the eyes,
seek medical advice.
• Prolonged contact with used engine oil can
cause skin cancer. Wear gloves or use a
barrier cream if necessary. Change out of oil-
soaked clothes and do not keep oily rags in
your pocket.
• Air conditioning refrigerant forms a
poisonous gas if exposed to a naked flame
(including a cigarette). It can also cause skin
burns on contact.
Asbestos
• Asbestos dust can cause cancer if inhaled
or swallowed. Asbestos may be found in
gaskets and in brake and clutch linings.
When dealing with such components it is
safest to assume that they contain asbestos.
Special hazards
Hydrofluoric acid
• This extremely corrosive acid is formed
when certain types of synthetic rubber, found
in some O-rings, oil seals, fuel hoses etc, are
exposed to temperatures above 400
0C. The
rubber changes into a charred or sticky
substance containing the acid. Once formed,
the acid remains dangerous for years. If it
gets onto the skin, it may be necessary to
amputate the limb concerned.
• When dealing with a vehicle which has
suffered a fire, or with components salvaged
from such a vehicle, wear protective gloves
and discard them after use.
The battery
• Batteries contain sulphuric acid, which
attacks clothing, eyes and skin. Take care
when topping-up or carrying the battery.
• The hydrogen gas given off by the battery
is highly explosive. Never cause a spark or
allow a naked light nearby. Be careful when
connecting and disconnecting battery
chargers or jump leads.
Air bags
• Air bags can cause injury if they go off
accidentally. Take care when removing the
steering wheel and/or facia. Special storage
instructions may apply.
Diesel injection equipment
• Diesel injection pumps supply fuel at very
high pressure. Take care when working on
the fuel injectors and fuel pipes.
Warning: Never expose the hands,
face or any other part of the body
to injector spray; the fuel can
penetrate the skin with potentially fatal
results.
Remember...
DO
• Do use eye protection when using power
tools, and when working under the vehicle.
• Do wear gloves or use barrier cream to
protect your hands when necessary.
• Do get someone to check periodically
that all is well when working alone on the
vehicle.
• Do keep loose clothing and long hair well
out of the way of moving mechanical parts.
• Do remove rings, wristwatch etc, before
working on the vehicle – especially the
electrical system.
• Do ensure that any lifting or jacking
equipment has a safe working load rating
adequate for the job.
A few tips
DON’T
• Don’t attempt to lift a heavy component
which may be beyond your capability – get
assistance.
• Don’t rush to finish a job, or take
unverified short cuts.
• Don’t use ill-fitting tools which may slip
and cause injury.
• Don’t leave tools or parts lying around
where someone can trip over them. Mop
up oil and fuel spills at once.
• Don’t allow children or pets to play in or
near a vehicle being worked on.

0•7Anti-theft audio system
Anti-theft audio system
General information
Some models are equipped with an audio
system having an anti-theft feature that will
render the stereo inoperative if stolen. If the
power source to the stereo is cut, the stereo
won’t work even if the power source is
immediately re-connected. If your vehicle is
equipped with this anti-theft system, do not
disconnect the battery or remove the stereo
unless you have the individual code number
for the stereo.
Refer to the owner’s handbook suppliedwith the vehicle for more complete
information on this audio system and its anti-
theft feature.
Unlocking procedure
1Turn on the radio. The word “CODE” should
appear on the display.
2Using the station preset selector buttons,
enter the five-digit code. If you make a
mistake when entering the code, continue
the five-digit sequence anyway. If you hear
a “beep,” however, stop immediately andstart the sequence over again. Note: Yo u
have three attempts to enter the correct
code. If the correct code isn’t entered in
three tries, you’ll have to wait one hour, with
the radio on, before you enter the codes
again.
5Once the code has been entered correctly,
the word “CODE” should disappear from the
display, and the radio should play (you’ll have
to tune-in and enter your preset stations,
however).
6If you have lost your code number, contact
a BMW dealer service department.
Instrument panel language display
On some later models, disconnecting the
battery may cause the instrument panel
display to default to the German language
(this does not usually apply to UK models). If
it is necessary to reset the correct language
after the battery is reconnected, proceed as
follows. With all the doors shut and theignition on (engine not running), press the trip
reset button until the panel displays the
desired language. There are eight languages
available. If you wish to bypass a particular
selection, release the reset button and press
again - this will cause the display to advance
to the next language. Once the correctlanguage has been selected, continue holding
the reset button until the display reads “I.O.
Version 2.0”. Continue holding the button until
it reads “H.P. Version 3.4”, then release the
button.

0•8Roadside Repairs
Jacking and wheel
changing
The jack supplied with the vehicle should
be used only for raising the vehicle when
changing a tyre or placing axle stands under
the frame.
Warning:Never crawl under the
vehicle or start the engine when
this jack is being used as the
only means of support.
When changing a wheel, the vehicle should
be on level ground, with the handbrake firmly
applied, and the wheels chocked. Select
reverse gear (manual transmission) or Park
(automatic transmission). Prise off the hub
cap (if equipped) using the tapered end of the
wheel brace. Loosen the wheel bolts half a
turn, leaving them in place until the wheel is
raised off the ground.
Position the head of the jack under the side
of the vehicle, making sure it engages with thepocket made for this purpose (just behind the
front wheel, or forward of the rear wheel).
Engage the wheel brace handle and turn it
clockwise until the wheel is raised off the
ground. Unscrew the bolts, remove the wheel
and fit the spare.
Refit the wheel bolts and tighten them
finger-tight. Lower the vehicle by turning the
wheel brace anti-clockwise. Remove the jack
and tighten the bolts in a diagonal pattern to
the torque listed in the Chapter 1
Specifications. If a torque wrench is not
available, have the torque checked by a BMW
dealer or tyre fitting specialist as soon as
possible. Refit the hubcap.
Towing
Vehicles with manual transmission can be
towed with all four wheels on the ground, if
necessary. Automatic transmission-equipped
vehicles can only be towed with all fourwheels on the ground providing that the
speed does not exceed 35 mph and the
distance is not over 50 miles, otherwise
transmission damage can result. For
preference, regardless of transmission type,
the vehicle should be towed with the driven
(rear) wheels off the ground.
Proper towing equipment, specifically
designed for the purpose, should be used,
and should be attached to the main structural
members of the vehicle, not to the bumpers or
bumper brackets. Sling-type towing
equipment must notbe used on these
vehicles.
Safety is a major consideration while
towing. The handbrake should be released,
and the transmission should be in neutral. The
steering must be unlocked (ignition switch
turned to position “1”). Remember that
power-assisted steering (where fitted) and the
brake servo will not work with the engine
switched off.
Jacking, towing and wheel changing

0•9Roadside Repairs
When jump-starting a car using a
booster battery, observe the following
precautions:
4Before connecting the booster
battery, make sure that the ignition is
switched off.
4Ensure that all electrical equipment
(lights, heater, wipers, etc) is
switched off.
4Make sure that the booster battery is
the same voltage as the discharged
one in the vehicle.
4If the battery is being jump-started
from the battery in another vehicle,
the two vehcles MUST NOT TOUCH
each other.
4Make sure that the transmission is in
neutral (or PARK, in the case of
automatic transmission).
Jump starting will get you out
of trouble, but you must correct
whatever made the battery go
flat in the first place. There are
three possibilities:
1The battery has been drained by
repeated attempts to start, or by
leaving the lights on.
2The charging system is not working
properly (alternator drivebelt slack
or broken, alternator wiring fault or
alternator itself faulty).
3The battery itself is at fault
(electrolyte low, or battery worn out).
Connect one end of the red jump lead to
the positive (+) terminal of the flat
batteryConnect the other end of the red lead to
the positive (+) terminal of the booster
battery.Connect one end of the black jump lead
to the negative (-) terminal of the
booster battery
Connect the other end of the black
jump lead to a bolt or bracket on the
engine block, well away from the
battery, on the vehicle to be started.
123
4
Make sure that the jump leads will not
come into contact with the fan, drive-
belts or other moving parts of the
engine.5
Start the engine using the booster
battery, then with the engine running at
idle speed, disconnect the jump leads in
the reverse order of connection.6
Jump starting

Fuel system
Idle speed
3-Series, E30
316 with M10/B18 engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 850 ± 50 rpm
316i with M40/B16 engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 800 ± 40 rpm
318i with M10/B18 engine (manual transmission) . . . . . . . . . . . . . 850 ± 50 rpm
318i with M10/B18 engine (automatic transmission) . . . . . . . . . . . 750 ± 50 rpm
318i with M40/B18 engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 800 ± 40 rpm
320i with M20/B20 engine (L-Jetronic) . . . . . . . . . . . . . . . . . . . . . . 800 ± 50 rpm
320i with M20/B20 engine (Motronic) . . . . . . . . . . . . . . . . . . . . . . . 760 ± 40 rpm
325i with M20/B25 engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 760 ± 40 rpm
5-Series, E28 (“old-shape”)
518 and 518i with M10/B18 engine . . . . . . . . . . . . . . . . . . . . . . . . 800 ± 50 rpm
All other models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 850 ± 50 rpm
5-Series, E34 (“new-shape”)
518i with M40/B18 engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 800 ± 40 rpm
520i with M20/B20M engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 760 ± 40 rpm
525i with M20/B25M engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 760 ± 40 rpm
530i with M30/B30M engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 800 ± 50 rpm
535i with M30/B35M engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 850 ± 50 rpm
CO% at 3000 rpm
3-Series, E30
316 with M10/B18 engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.5 to 1.0
316i and 318i with M40/B16 engine . . . . . . . . . . . . . . . . . . . . . . . . 0.7 ± 0.5
318i with M10/B18 engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.0 maximum
320i with M20/B20 engine (L-Jetronic) . . . . . . . . . . . . . . . . . . . . . . 1.0 ± 0.5
320i with M20/B20 engine (Motronic) . . . . . . . . . . . . . . . . . . . . . . . 0.7 ± 0.5
325i with M20/B25 engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.0 ± 0.5
5-Series, E28 (“old-shape”)
518 and 518i with M10/B18 engine . . . . . . . . . . . . . . . . . . . . . . . . 1.0 maximum
525i with M30/B25 engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.0 ± 0.5
528i with M30/B28 engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.5 maximum
535i with M30/B34 engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.3 to 1.5
M535i with M30/B34 engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.3 to 1.5
5-Series, E34 (“new-shape”)
All models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.7 ± 0.5
Air filter element
M10 engines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Champion W155 (round) or U504 (square)
M20 engines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Champion U504 or U527
M30 engines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Champion U504 or U527
M40 engines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Champion U527
Fuel filter (all fuel injection engines) . . . . . . . . . . . . . . . . . . . . . . . . . . . . Champion L206
Ignition system
Spark plug type
M10, M20 and M30 engines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Champion N9YCC
M40 engines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Champion C9YCC
Spark plug gap* . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.8 mm
Spark plug (HT) leads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Champion type not available
* The spark plug gap quoted is that recommended by Champion for their specified plugs listed above. If spark plugs of any other type are to be
fitted, refer to their manufacturer’s spark plug gap recommendations.
Brakes
Disc brake pad thickness (minimum) . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.0 mm
Drum brake shoe lining thickness (minimum) . . . . . . . . . . . . . . . . . . . . . 2.0 mm
Wiper blades
Windscreen
3-Series . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Champion X-5103
3-Series passenger side from 1991 . . . . . . . . . . . . . . . . . . . . . . . . . . Champion X-5103 (20 inch) or Champion X-5303 (21 inch)
5-Series, E28 (“old-shape”) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Champion X-4503
5-Series, E34 (“new-shape”) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Champion type not available
Tailgate
3-Series . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Champion X-4503
5-Series . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Champion type not available
1•2Servicing Specifications

1•5
Underbonnet view (left-hand side) of a
UK model 318i (1988)
1 Radiator
2 Intake manifold
3 Idle control valve
4 Accelerator cable
5 Diagnostic/service indicator resetting
socket
6 Fuse/relay box
7 Brake hydraulic fluid reservoir
8 Airflow meter
9 Air cleaner unit
10 Radiator filler cap
11 Radiator top hose
12 Oil filter housing
Underbonnet view (right-hand side) of a
UK model 318i (1988)
1 Oil filler cap
2 Valve cover
3 Engine oil filler dipstick
4 Viscous cooling fan
5 Distributor cap cover
6 Bottom hose
7 Windscreen washer fluid reservoir
8 Ignition coil
9 Clutch hydraulic fluid reservoir
10 Battery
1
Maintenance and Servicing

1 Introduction
This Chapter is designed to help the home
mechanic maintain his or her vehicle with the
goals of maximum performance, economy,
safety and reliability in mind. Included is a
master maintenance schedule, followed by
procedures dealing specifically with each item
on the schedule. Visual checks, adjustments,
component renewal and other helpful items
are included. Refer to the accompanying
illustrations of the engine compartment and
the underside of the vehicle for the locations
of various components. Servicing the vehicle,
in accordance with the mileage/time
maintenance schedule and the step-by-step
procedures, will result in a planned
maintenance programme that should produce
a long and reliable service life. Keep in mind
that it is a comprehensive plan, so maintaining
some items but not others at specified
intervals, will not produce the same results.
2 Routine maintenance
As you service the vehicle, you will discover
that many of the procedures can - and should
- be grouped together, because of the nature
of the particular procedure you’re performing,
or because of the close proximity of two
otherwise-unrelated components to one
another. For example, if the vehicle is raised
for chassis lubrication, you should inspect the
exhaust, suspension, steering and fuelsystems while you’re under the vehicle. When
the wheels are removed for other work, it
makes good sense to check the brakes, since
the wheels are already removed. Finally, let’s
suppose you have to borrow a torque wrench.
Even if you only need it to tighten the spark
plugs, you might as well check the torque of
as many critical nuts and bolts as time allows.
The first step in this maintenance
programme is to prepare yourself before the
actual work begins. Read through all the
procedures you’re planning to do, then gather
up all the parts and tools needed. If it looks
like you might run into problems during a
particular job, seek advice from a mechanic or
an experienced do-it-yourselfer.
3 Engine “tune-up”-
general information
The term “tune-up” is used in this manual to
represent a combination of individual
operations rather than one specific procedure.
If, from the time the vehicle is new, the
routine maintenance schedule is followed
closely, and frequent checks are made of fluid
levels and high-wear items, as suggested
throughout this manual, the engine will be
kept in relatively good running condition, and
the need for additional work will be minimised.
More likely than not, however, there will be
times when the engine is running poorly due
to a lack of regular maintenance. This is even
more likely if a used vehicle, which has not
received regular and frequent maintenance
checks, is purchased. In such cases, an
engine tune-up will be needed outside of the
regular maintenance intervals. The first step in any tune-up or diagnostic
procedure to help correct a poor-running
engine is a cylinder compression check. A
compression check (see Chapter 2B) will help
determine the condition of internal engine
components, and should be used as a guide
for tune-up and repair procedures. If, for
instance, a compression check indicates
serious internal engine wear, a conventional
tune-up will not improve the performance of
the engine, and would be a waste of time and
money. Because of its importance, the
compression check should be done by
someone with the right equipment, and the
knowledge to use it properly.
The following procedures are those most
often needed to bring a generally poor-
running engine back into a proper state of
tune.
Minor tune-up
Check all engine-related fluids (Section 4)
Check all underbonnet hoses (Section 10)
Check and adjust the drivebelts (Sec-
tion 11)
Clean, inspect and test the battery (Sec-
tion 13)
Renew the spark plugs (Section 14)
Inspect the spark plug HT leads, distributor
cap and rotor (Section 15)
Check the air filter (Section 20)
Check the cooling system (Section 22)
Major tune-up
All items listed under minor tune-up, plus . . .
Check the ignition system (see Chapter 5)
Check the charging system (see Chapter 5)
Check the fuel system (see Chapter 4)
Renew the spark plug HT leads, distributor
cap and rotor (Section 15)
1•7
1
Routine Maintenance
Weekly checks
4 Fluid level checks
1
Note:The following are fluid level checks to
be done on a 250-mile or weekly basis.
Additional fluid level checks can be found in
specific maintenance procedures which
follow. Regardless of intervals, be alert to fluid
leaks under the vehicle, which would indicate
a fault to be corrected immediately.
1Fluids are an essential part of the
lubrication, cooling, brake and windscreen
washer systems. Because the fluids gradually
become depleted and/or contaminated during
normal operation of the vehicle, they must be
periodically replenished. See “Lubricants and
fluids”at the beginning of this Chapter before
adding fluid to any of the following
components. Note:The vehicle must be on
level ground when any fluid levels are
checked.
Engine oil
2Engine oil is checked with a dipstick, which
is located on the side of the engine (refer to
the underbonnet illustrations in this Chapter
for dipstick location). The dipstick extends
through a metal tube down into the sump.
3The engine oil should be checked before
the vehicle has been driven, or at least
15 minutes after the engine has been shut off.
4Pull the dipstick out of the tube, and wipe
all of the oil away from the end with a clean
rag or paper towel. Insert the clean dipstick all
the way back into the tube, and pull it out
again. Note the oil at the end of the dipstick.
At its highest point, the oil should be betweenthe two notches or marks (see illustration).
5It takes one litre of oil to raise the level from
the lower mark to the upper mark on the
dipstick. Do not allow the level to drop below
the lower mark, or oil starvation may cause
4.4 The oil level should be kept between
the two marks, preferably at or near the
upper one - if it isn’t, add enough oil to
bring the level to the upper mark
If the oil is checked
immediately after driving the
vehicle, some of the oil will
remain in the upper part of
the engine, resulting in an inaccurate
reading on the dipstick.

move the component away from the engine to
tighten the belt, or towards the engine to
loosen the belt. Hold the accessory in
position, and check the belt tension. If it is
correct, tighten the two bolts until just tight,
then recheck the tension. If the tension is still
correct, tighten the bolts.
8It will often be necessary to use some sort
of lever to move the accessory while the belt
is adjusted. If this must be done to gain the
proper leverage, be very careful not to
damage the component being moved, or the
part being prised against.
Renewal
9To renew a belt, follow the instructions
above for adjustment, but remove the belt
from the pulleys.
10In some cases, you will have to remove
more than one belt, because of their
arrangement on the front of the engine.
Because of this, and the fact that belts will
tend to fail at the same time, it is wise to
renew all belts together. Mark each belt and
its appropriate pulley groove, so all renewed
belts can be fitted in their proper positions.
11It is a good idea to take the old belts with
you when buying new ones, in order to make
a direct comparison for length, width and
design.
12Recheck the tension of new belts after a
few hundred miles.
12 Engine idle speed and CO
level check and adjustment
4
Note:The engine should be at normal
operating temperature, with correct ignition
timing and valve clearances (where
adjustable). The air filter should be in good
condition, and all electrical components
(including the air conditioning, where fitted)
should be switched off.
Carburettor
1Connect a tachometer and exhaust gas
analyser (CO meter) to the engine.
2Start the engine and allow it to idle.
3Check that the idle speed is as given in the
Specifications. Adjustment of the idle speed is
only possible on the 2B4 carburettor. Turn the
carburettor idle speed adjustment screw until
the engine idles at the correct speed (see
illustration).
4If the idle speed is low on the 2BE
carburettor, and all wiring to the carburettor is
in good condition, it is possible to connect a
resistance into the control circuit. This should
be carried out by your BMW dealer.
5Check that the CO reading is as given in the
Specifications. If not, turn the carburettor idle
mixture adjustment screw until the mixture is
correct (see illustration).
L-Jetronic
6Connect a tachometer and CO meter to the
engine. BMW technicians use a special CO
tester with a probe connected into the
exhaust manifold, but the normal type of
tester which locates in the exhaust tailpipe
can be used instead. Note however that on
models with a catalytic converter, meaningful
CO readings will not be obtained at the
tailpipe.
7Start the engine and allow it to idle.
8Check that the idle speed is as given in
Specifications. If not, remove the tamperproof
cap from the throttle housing, and turn the idle
adjustment screw until the speed is correct.
9Check that the CO reading is as given in the
Specifications. The mixture control screw is
located on the airflow meter, and a specialtool (BMW number 13 1 060) may be required
to make the adjustment.
Motronic
10Connect a tachometer and CO meter to
the engine. BMW technicians use a special
CO tester with a probe connected into the
exhaust manifold, but the normal type of
tester which locates in the exhaust tailpipe
may be used instead. Note however that on
models with a catalytic converter, meaningful
CO readings will not be obtained at the
tailpipe.
11It is not possible to adjust the idle speed
manually, as the idle air stabiliser valve is
activated by the electronic control unit. If the
idle speed is not within the specified range
with the engine at normal operating
temperature, check for a leak in the air inlet
system, and also check the operation of the
idle air stabiliser valve (see Chapter 4).
12Check that the CO reading is as given in
the Specifications. If adjustment is required,
prise out the tamperproof plug from the
airflow meter, and turn the adjustment screw
to set the CO content (on some models, an
Allen key will be required). Fit a new
tamperproof plug on completion (see
illustrations).
1•15
12.12a Removing the tamperproof plug
from the airflow meter
12.5 Mixture adjustment screw (2) on the
2B4 carburettor
12.3 Idle speed adjustment screw on the
2B4 carburettor (shown with the
carburettor removed)
12.12b Adjusting the CO on the Motronic
system
1
Every 6000 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

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