1990 BMW 3 SERIES Chain

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

detach them. Pieces of masking tape with
numbers or letters written on them work well
(see illustration).
6Label and detach all coolant hoses from the
engine (see Chapter 3).
7Remove the cooling fan, shroud and
radiator (see Chapter 3). Note:On the M40
engine, it is only necessary to remove the
cooling fan and shroud; however, prevent
damage to the radiator by covering it with a
piece of wood or cardboard.
8Remove the drivebelts (see Chapter 1).
9Disconnect the fuel lines from the fuel rail
(see Chapter 4).
Warning: Fuel is extremely
flammable, so take extra
precautions when you work on
any part of the fuel system. Don’t
smoke, or allow open flames or bare light
bulbs, near the work area, and don’t work
in a garage where a natural gas-type
appliance (such as a water heater or
clothes dryer) with a pilot light is present.
If you spill any fuel on your skin, rinse it off
immediately with soap and water. When
you perform any kind of work on the fuel
system, wear safety glasses, and have a
fire extinguisher on hand.
10Disconnect the accelerator cable (see
Chapter 4) and kickdown linkage/speed
control cable (see Chapter 7B), if applicable,
from the engine.
11Where fitted, unbolt the power steering
pump (see Chapter 10). Leave the lines/hoses
attached, and make sure the pump is kept in
an upright position in the engine compartment
(use wire or rope to restrain it out of the way).
12On air-conditioned models, unbolt the
compressor (see Chapter 3) and set it aside,
or tie it up out of the way. Do not disconnect
the hoses.
13Drain the engine oil (see Chapter 1) and
remove the filter. Remove the engine splash
guard from under the engine.
14Remove the starter motor (see Chapter 5).15Remove the alternator (see Chapter 5).
This is not essential on all models, but it is a
good idea in any case to avoid accidental
damage.
16Unbolt the exhaust system from the
engine (see Chapter 4).
17If you’re working on a vehicle with an
automatic transmission, remove the torque
converter-to-driveplate fasteners (see
Chapter 7B). On the M40 engine, unbolt the
automatic transmission fluid coolant pipes
from the sump.
18Support the transmission with a jack.
Position a block of wood between them, to
prevent damage to the transmission. Special
transmission jacks with safety chains are
available - use one if possible.
19Attach an engine sling or a length of chain
to the lifting brackets on the engine. If the
brackets have been removed, the chain can
be bolted directly to the intake manifold studs,
but place a flat washer between the chain and
the nut, and tighten the nut all the way up to
the chain, to avoid the possibility of the studs
bending.
20Roll the hoist into position and connect
the sling to it. Take up the slack in the sling or
chain, but don’t lift the engine.
Warning: DO NOT place any part
of your body under the engine
when it’s supported only by a
hoist or other lifting device.
21On M10, M20 and M30 engines, remove
the transmission rear crossmember, and
slightly lower the rear of the transmission.
22Remove the transmission-to-engine block
bolts using a Torx socket. Note:The bolts
holding the bellhousing to the engine block
will require a swivel at the socket, and a very
long extension going back towards the
transmission.
23Remove the engine mounting-to-frame
bracket nuts. On the M40 engine, unbolt the
dampers from the mountings.
24Recheck to be sure nothing is still
connecting the engine to the transmission or
vehicle. Disconnect anything still remaining.
25Raise the engine slightly. Carefully work it
forwards to separate it from the transmission.
If you’re working on a vehicle with an
automatic transmission, you may find the
torque converter comes forward with theengine. If it stays with the transmission, leave
it, but you may find it easier to let it come
forward until it can be grasped easier and be
pulled from the crankshaft. Note:When
refitting the torque converter to the
transmission before the engine is refitted, be
sure to renew the transmission front pump
seal, which will probably be damaged when
the converter comes out with the engine.
Either method is acceptable, but be prepared
for some fluid to leak from the torque
converter if it comes out of the transmission. If
you’re working on a vehicle with a manual
transmission, draw the engine forwards until
the input shaft is completely disengaged from
the clutch. Slowly raise the engine out of the
engine compartment. Check carefully to make
sure everything is disconnected.
26Remove the flywheel/driveplate (and
where applicable, the engine rear plate), and
mount the engine on an engine stand (see
illustration). Do not turn the M40 engine
upside-down (see Cautionin Section 4).
Refitting
27Check the engine and transmission
mountings. If they’re worn or damaged, renew
them.
28Refit the flywheel or driveplate (see
Chapter 2A). If you’re working on a manual
transmission vehicle, refit the clutch and
pressure plate (see Chapter 7A). Now is a
good time to fit a new clutch.
29If the torque converter came out with the
engine during removal, carefully refit the
converter into the transmission before the
engine is lowered into the vehicle.
30Carefully lower the engine into the engine
compartment - make sure the engine
mountings line up.
31If you’re working on an automatic
transmission vehicle, guide the torque
converter onto the crankshaft following the
procedure outlined in Chapter 7B.
32If you’re working on a manual
transmission vehicle, apply a dab of high-
melting-point grease to the input shaft, and
guide it into the clutch and crankshaft pilot
bearing until the bellhousing is flush with the
engine block.. Do not allow the weight of the
engine to hang on the input shaft.
33Refit the transmission-to-engine bolts,
and tighten them securely.
Caution: DO NOT use the bolts to
force the transmission and
engine together.
34Refit the remaining components in the
reverse order of removal.
35Add coolant, oil, power steering and
transmission fluid as needed.
2B•6 General engine overhaul procedures
5.26 Removing the engine rear plate -
M40 engine5.5 Label each wire before unplugging the
connector
If there’s any possibility of
confusion, make a sketch of
the engine compartment and
clearly label the lines, hoses
and wires.
It may be necessary to rock
the engine slightly, or to turn
the crankshaft, to allow the
input shaft splines to mate
with the clutch plate

36Run the engine and check for leaks and
proper operation of all accessories, then refit
the bonnet and test drive the vehicle.
37Where necessary, have the air
conditioning system recharged and leak-
tested.
6 Engine overhaul- alternatives
The do-it-yourselfer is faced with a number
of options when performing an engine
overhaul. The decision to renew the engine
block, piston/connecting rod assemblies and
crankshaft depends on a number of factors,
with the number one consideration being the
condition of the block. Other considerations
are cost, access to machine shop facilities,
parts availability, time required to complete
the project, and the extent of prior mechanical
experience on the part of the do-it-yourselfer.
Some of the alternatives include:
Individual parts - If the inspection
procedures reveal that the engine block and
most engine components are in re-usable
condition, purchasing individual parts may be
the most economical alternative. The block,
crankshaft and piston/connecting rod
assemblies should all be inspected carefully.
Even if the block shows little wear, the
cylinder bores should be surface-honed.
Crankshaft kit- A crankshaft kit (where
available) consists of a reground crankshaft
with matched undersize new main and
connecting big-end bearings. Sometimes,
reconditioned connecting rods and new
pistons and rings are included with the kit
(such a kit is sometimes called an “engine
kit”). If the block is in good condition, but the
crankshaft journals are scored or worn, a
crankshaft kit and other individual parts may
be the most economical alternative.
Short block- A short block consists of an
engine block with a crankshaft and
piston/connecting rod assemblies already
fitted. New bearings are fitted, and all
clearances will be correct. The existing
camshaft, valve train components, cylinder
head and external parts can be bolted to the
short block with little or no machine shop
work necessary.
Full block - A “full” or “complete” block
consists of a short block plus an oil pump,
sump, cylinder head, valve cover, camshaft
and valve train components, timing sprockets
and chain (or belt) and timing cover. All
components are fitted with new bearings,
seals and gaskets used throughout. The
refitting of manifolds and external parts is all
that’s necessary.
Give careful thought to which alternative is
best for you, and discuss the situation with
local machine shops, parts dealers and
experienced rebuilders before ordering or
purchasing new parts.
7 Engine overhaul-
dismantling sequence
1It’s much easier to dismantle and work on
the engine if it’s mounted on a portable
engine stand. A stand can often be hired quite
cheaply from a tool hire shop. Before the
engine is mounted on a stand, the
flywheel/driveplate should be removed from
the engine.
2If a stand isn’t available, it’s possible to
dismantle the engine with it blocked up on the
floor. Be extra-careful not to tip or drop the
engine when working without a stand.
3If you’re going to obtain a rebuilt engine, all
the external components listed below must
come off first, to be transferred to the new
engine if applicable. This is also the case if
you’re doing a complete engine overhaul
yourself. Note:When removing the external
components from the engine, pay close
attention to details that may be helpful or
important during refitting. Note the fitted
position of gaskets, seals, spacers, pins,
brackets, washers, bolts and other small items.
Alternator and brackets
Emissions control components
Distributor, HT leads and spark plugs
Thermostat and housing cover
Water pump
Fuel injection/carburettor and fuel system
components
Intake and exhaust manifolds
Oil filter and oil pressure sending unit
Engine mounting brackets (see illustration)
Clutch and flywheel/driveplate
Engine rear plate (where applicable)
4If you’re obtaining a short block, which
consists of the engine block, crankshaft,
pistons and connecting rods all assembled,
then the cylinder head, sump and oil pump
will have to be removed as well. See Section 6
for additional information regarding the
different possibilities to be considered.
5If you’re planning a complete overhaul, the
engine must be dismantled and the internal
components removed in the following general
order:
Valve cover
Intake and exhaust manifolds
Timing belt or chain covers
Timing chain/belt
Water pump
Cylinder head
Sump
Oil pump
Piston/connecting rod assemblies
Crankshaft and main bearings
Camshaft
Rocker shafts and rocker arms (M10, M20
and M30 engines)
Cam followers and hydraulic tappets
(M40 engine)
Valve spring retainers and springs
Valves
6Before beginning the dismantling andoverhaul procedures, make sure the following
items are available. Also, refer to Section 21
for a list of tools and materials needed for
engine reassembly.
Common hand tools
Small cardboard boxes or plastic bags for
storing parts
Compartment-type metal box for storing
the hydraulic tappets (M40 engine)
Gasket scraper
Ridge reamer
Vibration damper puller
Micrometers
Telescoping gauges
Dial indicator set
Valve spring compressor
Cylinder surfacing hone
Piston ring groove cleaning tool
Electric drill motor
Tap and die set
Wire brushes
Oil gallery brushes
Cleaning solvent
8 Cylinder head- dismantling
4
1Remove the cylinder head (see Chapter 2A).
2Remove the oil supply tube from its
mounting on top of the cylinder head (see
illustrations). Note:It’s important to renew
the seals under the tube mounting bolts.
General engine overhaul procedures 2B•7
7.3 Engine left-hand mounting bracket -
M40 engine
8.2a Remove the oil tube from the top of
the cylinder head (M10 engine). Be sure to
note the location of all gaskets and
washers for reassembly
2B

carbon deposits or cylinder wear have
produced ridges, they must be completely
removed with a special tool called a ridge
reamer (see illustration). Follow the
manufacturer’s instructions provided with the
tool. Failure to remove the ridges before
attempting to remove the piston/connecting
rod assemblies may result in piston ring
breakage.
2After the cylinder ridges have been
removed, turn the engine upside-down so the
crankshaft is facing up.
3Before the connecting rods are removed,
check the side play with feeler gauges. Slide
them between the first connecting rod and
crankshaft web until no play is apparent (see
illustration). The side play is equal to the
thickness of the feeler gauge(s). If the side
play exceeds the service limit, new
connecting rods will be required. If new rods
(or a new crankshaft) are fitted, ensure that
some side play is retained (if not, the rods will
have to be machined to restore it - consult a
machine shop for advice if necessary). Repeat
the procedure for the remaining connecting
rods.
4Check the connecting rods and caps for
identification marks. If they aren’t plainly
marked, use a small centre-punch to make
the appropriate number of indentations (see
illustration)on each rod and cap (1, 2, 3, etc.,
depending on the cylinder they’re associated
with).
5Loosen each of the connecting rod cap
nuts/bolts a half-turn at a time until they can
be removed by hand. Remove the No 1
connecting rod cap and bearing shell. Don’t
drop the bearing shell out of the cap.
6Where applicable, slip a short length of
plastic or rubber hose over each connecting
rod cap stud to protect the crankshaft journal
and cylinder wall as the piston is removed
(see illustration).
7Remove the bearing shell, and push the
connecting rod/piston assembly out through
the top of the engine. Use a wooden hammer
handle to push on the upper bearing surface
in the connecting rod. If resistance is felt,
double-check to make sure that all of the
ridge was removed from the cylinder.8Repeat the procedure for the remaining
cylinders.
9After removal, reassemble the connecting
rod caps and bearing shells in their respective
connecting rods, and refit the cap nuts/bolts
finger-tight. Leaving the old bearing shells in
place until reassembly will help prevent the
connecting big-end bearing surfaces from
being accidentally nicked or gouged.
10Don’t separate the pistons from the
connecting rods (see Section 18).
13 Crankshaft- removal
5
Note: The crankshaft can be removed only
after the engine has been removed from the
vehicle. It’s assumed that the flywheel or
driveplate, vibration damper, timing chain or
belt, sump, oil pump and piston/connecting
rod assemblies have already been removed.
The rear main oil seal housing must be
unbolted and separated from the block before
proceeding with crankshaft removal.
1Before the crankshaft is removed, check
the endfloat. Mount a dial indicator with the
stem in line with the crankshaft and touching
the nose of the crankshaft, or one of its webs
(see illustration).
2Push the crankshaft all the way to the rear,and zero the dial indicator. Next, prise the
crankshaft to the front as far as possible, and
check the reading on the dial indicator. The
distance that it moves is the endfloat. If it’s
greater than the maximum endfloat listed in
this Chapter’s Specifications, check the
crankshaft thrust surfaces for wear. If no wear
is evident, new main bearings should correct
the endfloat.
3If a dial indicator isn’t available, feeler
gauges can be used. Identify the main bearing
with the thrust flanges either side of it - this is
referred to as the “thrust” main bearing (see
Section 24, paragraph 6). Gently prise or push
the crankshaft all the way to the front of the
engine. Slip feeler gauges between the
crankshaft and the front face of the thrust
main bearing to determine the clearance.
4Check the main bearing caps to see if
they’re marked to indicate their locations.
They should be numbered consecutively from
the front of the engine to the rear. If they
aren’t, mark them with number-stamping dies
or a centre-punch (see illustration). Main
bearing caps generally have a cast-in arrow,
which points to the front of the engine.
Loosen the main bearing cap bolts a quarter-
turn at a time each, working from the outer
ends towards the centre, until they can be
removed by hand. Note if any stud bolts are
used, and make sure they’re returned to their
original locations when the crankshaft is
refitted.
General engine overhaul procedures 2B•13
12.4 Mark the big-end bearing caps in
order from the front of the engine to the
rear (one mark for the front cap, two for
the second one and so on)12.3 Check the connecting rod side play
with a feeler gauge as shown12.1 A ridge reamer is required to remove
the ridge from the top of each cylinder - do
this before removing the pistons!
13.1 Checking crankshaft endfloat with a
dial indicator
12.6 To prevent damage to the crankshaft
journals and cylinder walls, slip sections of
rubber or plastic hose over the rod bolts
before removing the pistons
2B

3When examining the bearings, remove
them from the engine block, the main bearing
caps, the connecting rods and the rod caps,
and lay them out on a clean surface in the
same general position as their location in the
engine. This will enable you to match any
bearing problems with the corresponding
crankshaft journal.
4Dirt and other foreign particles get into the
engine in a variety of ways. It may be left in
the engine during assembly, or it may pass
through filters or the crankcase ventilation
(PCV) system. It may get into the oil, and from
there into the bearings. Metal chips from
machining operations and normal engine wear
are often present. Abrasives are sometimes
left in engine components after recondi-
tioning, especially when parts are not
thoroughly cleaned using the proper cleaning
methods. Whatever the source, these foreign
objects often end up embedded in the soft
bearing material, and are easily recognised.
Large particles will not embed in the bearing,
and will score or gouge the bearing and
journal. The best prevention for this cause of
bearing failure is to clean all parts thoroughly,
and to keep everything spotlessly-clean
during engine assembly. Frequent and regular
engine oil and filter changes are also
recommended.
5Lack of lubrication (or lubrication
breakdown) has a number of interrelated
causes. Excessive heat (which thins the oil),
overloading (which squeezes the oil from the
bearing face) and oil “leakage” or “throw off”
(from excessive bearing clearances, worn oil
pump, or high engine speeds) all contribute to
lubrication breakdown. Blocked oil passages,
which usually are the result of misaligned oil
holes in a bearing shell, will also oil-starve a
bearing and destroy it. When lack of
lubrication is the cause of bearing failure, the
bearing material is wiped or extruded from the
steel backing of the bearing. Temperatures
may increase to the point where the steel
backing turns blue from overheating.
6Driving habits can have a definite effect on
bearing life. Full-throttle, low-speed operation
(labouring the engine) puts very high loads onbearings, which tends to squeeze out the oil
film. These loads cause the bearings to flex,
which produces fine cracks in the bearing
face (fatigue failure). Eventually, the bearing
material will loosen in places, and tear away
from the steel backing. Short-trip driving
leads to corrosion of bearings, because
insufficient engine heat is produced to drive
off the condensation and corrosive gases.
These products collect in the engine oil,
forming acid and sludge. As the oil is carried
to the engine bearings, the acid attacks and
corrodes the bearing material.
7Incorrect bearing refitting during engine
assembly will lead to bearing failure as well.
Tight-fitting bearings leave insufficient bearing
oil clearance, and will result in oil starvation.
Dirt or foreign particles trapped behind a
bearing shell result in high spots on the
bearing, which will lead to failure.
21 Engine overhaul-
reassembly sequence
1Before beginning engine reassembly, make
sure you have all the necessary new parts,
gaskets and seals, as well as the following
items on hand:
Common hand tools
A torque wrench
Piston ring refitting tool
Piston ring compressor
Vibration damper refitting tool
Short lengths of rubber or plastic hose to fit
over connecting rod bolts (where
applicable)
Plastigage
Feeler gauges
A fine-tooth file
New engine oil
Engine assembly oil or molybdenum
disulphide (“moly”) grease
Gasket sealant
Thread-locking compound
2In order to save time and avoid problems,
engine reassembly should be done in the
following general order:Piston rings
Crankshaft and main bearings
Piston/connecting rod assemblies
Oil pump
Sump
Cylinder head assembly
Timing belt or chain and tensioner
assemblies
Water pump
Timing belt or chain covers
Intake and exhaust manifolds
Valve cover
Engine rear plate
Flywheel/driveplate
22 Piston rings- refitting
2
1Before fitting the new piston rings, the ring
end gaps must be checked. It’s assumed that
the piston ring side clearance has been
checked and verified (see Section 18).
2Lay out the piston/connecting rod
assemblies and the new ring sets, so that the
ring sets will be matched with the same piston
and cylinder during the end gap measurement
and engine assembly.
3Insert the top ring into the first cylinder, and
square it up with the cylinder walls by pushing
it in with the top of the piston (see illustration).
The ring should be near the bottom of the
cylinder, at the lower limit of ring travel.
4To measure the end gap, slip feeler gauges
between the ends of the ring until a gauge equal
to the gap width is found(see illustration). The
feeler gauge should slide between the ring ends
with a slight amount of drag. Compare the
measurement to this Chapter’s Specifications.
If the gap is larger or smaller than specified,
double-check to make sure you have the
correct rings before proceeding.
5If the gap is too small, it must be enlarged,
or the ring ends may come in contact with
each other during engine operation, which
can cause serious damage to the engine. The
end gap can be increased by filing the ring
ends very carefully with a fine file. Mount the
2B•18 General engine overhaul procedures
22.5 If the end gap is too small, clamp a
file in a vice, and file the ring ends (from
the outside in only) to enlarge the gap
slightly22.4 With the ring square in the cylinder,
measure the end gap with a feeler gauge22.3 When checking piston ring end gap,
the ring must be square in the cylinder
bore (this is done by pushing the ring down
with the top of a piston as shown)

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

4On some models, working inside the boot,
you can remove the trim to access the upper
mounting nuts; on later models, you’ll have to
remove the rear seat back to get at the upper
mounting nuts. On Touring (Estate) models,
remove the side backrest and rear seat belt
reels, and unscrew the centring shell on the
wheel arch. On Convertibles, simply remove
the top from the recessed well behind the
passenger compartment, and remove the
small rubber access cover. As you remove the
mounting nuts (see illustration), have an
assistant support the shock absorber from
below so it doesn’t fall out.
5Look for oil leaking past the seal in the top
of the shock absorber body. Inspect the
rubber bushings in the shock absorber eye. If
they’re cracked, dried or torn, renew them. To
test the shock absorber, grasp the shock
absorber body firmly with one hand, and push
the damper rod in and out with the other. The
strokes should be smooth and firm. If the rod
goes in and out too easily, or unevenly, the
shock absorber is defective and must be
renewed.
Refitting
6Fit the shock absorbers in the reverse order
of removal, but don’t tighten the mounting
bolts and nuts yet.
7Bounce the rear of the vehicle a couple of
times to settle the bushings, then tighten the
nuts and bolts to the torque values listed in
this Chapter’s Specifications.
10 Rear coil springs (3-Series)-
removal and refitting
4
Note: Although coil springs don’t always wear
out simultaneously, renew both left and right
springs at the same time, to prevent handling
peculiarities or abnormal ride quality.
Removal
1Loosen the wheel bolts. Chock the front
wheels, then raise the rear of the vehicle andsupport it securely on axle stands. Make sure
the stands don’t interfere with the rear
suspension when it’s lowered and raised
during this procedure. Remove the wheels.
2Disconnect the mountings and brackets
which support the rear portion of the exhaust
system, and temporarily lower the exhaust
system (see Chapter 4). Lower the exhaust
system only enough to lower the suspension
and remove the springs. Suspend the exhaust
with a piece of wire.
3Support the differential with a trolley jack,
then remove the differential rear mounting
bolt. Push the differential down, and wedge it
into this lowered position with a block of
wood. This reduces the drive angle,
preventing damage to the CV joints when the
trailing arms are lowered to remove the
springs.
4Place a trolley jack under the trailing arm.
5If the vehicle has a rear anti-roll bar,
disconnect the bar from its connecting links,
or disconnect the links from the trailing arms
(see Section 12).
6Loop a chain through the coil spring, and
bolt the chain together, to prevent the coil
spring from popping out when the trailing arm
is lowered. Be sure to leave enough slack in
the chain to allow the spring to extend
completely.
7Disconnect the shock absorber lower
mounting bolt (see Section 9), carefully lower
the trailing arm and remove the coil spring.
Refitting
8Refitting is the reverse of removal. As the
trailing arm is raised back up, make sure the
spring seats properly.
11 Rear shock absorber/coil
spring assembly (5-Series)-
removal and refitting
4
Removal
Note:Although shock absorbers don’t always
wear out simultaneously, renew both left and
right shock absorbers at the same time, to
prevent handling peculiarities or abnormal ride
quality.1Loosen the wheel bolts, then chock the
front wheels. Raise the vehicle and support it
securely on axle stands. Remove the wheels.
2Remove the shock absorber lower
mounting bolt (see illustration).
3On early models, peel back the trim inside
the luggage compartment far enough to
access the upper mounting nuts. To get at the
upper mounting nuts on later models, first
remove the rear seat cushion (see Chap-
ter 11), then remove the two bolts holding the
rear seat backrest, and remove the backrest.
Support the trailing arm with a jack, and
remove the upper mounting nuts (see
illustration). Lower the jack, and remove the
shock absorber and the gasket. To separate
the shock absorber and spring, refer to
Section 6.
Refitting
4Refitting is the reverse of removal. Don’t
forget to fit the gasket between the upper end
of the shock absorber and the body. Tighten
the upper nuts to the torque listed in this
Chapter’s Specifications. Don’t tighten the
lower bolt until the vehicle is lowered.
5Lower the vehicle, and with it sitting at the
normal ride height, tighten the lower bolt to
the torque listed in this Chapter’s Specifi-
cations.
12 Rear anti-roll bar-
removal and refitting
2
Removal
Note:The rear anti-roll bar is mounted
basically the same way on all models. Follow
these general removal and refitting
procedures, keeping in mind any variations.
1Chock the front wheels, then raise the rear
of the vehicle and support it securely on axle
stands.
2Remove the anti-roll bar bracket bolts or
nuts (see illustration).
3Disconnect the anti-roll bar from the link at
each end of the bar (see illustrations)and
detach the anti-roll bar.
Suspension and steering systems 10•9
11.3 Shock absorber upper mounting nuts
(arrowed) on a later (E34) 5-Series model11.2 Remove the shock absorber lower
mounting bolt (arrowed)9.4 Shock absorber upper mounting nuts
(arrowed) - late-model convertible shown.
On other early models, upper nuts are
accessible from the luggage compartment;
on later models, they’re behind the back of
the rear seat, up under the parcel shelf
10

REF•10Fault Finding
Engine will not rotate when attempting to start
m mBattery terminal connections loose or corroded (Chapter 1).
m mBattery discharged or faulty (Chapter 1).
m mAutomatic transmission not completely engaged in Park (Chap-
ter 7B) or (on models with a clutch switch) clutch not completely
depressed (Chapter 8).
m mBroken, loose or disconnected wiring in the starting circuit
(Chapters 5 and 12).
m mStarter motor pinion jammed in flywheel ring gear (Chapter 5).
m mStarter solenoid faulty (Chapter 5).
m mStarter motor faulty (Chapter 5).
m mIgnition switch faulty (Chapter 12).
m mStarter pinion or flywheel teeth worn or broken (Chapter 5).
m mEngine internal problem (Chapter 2B).
Engine rotates, but will not start
m
mFuel tank empty.
m mBattery discharged (engine rotates slowly) (Chapter 5).
m mBattery terminal connections loose or corroded (Chapter 1).
m mLeaking fuel injector(s), faulty fuel pump, pressure regulator, etc
(Chapter 4).
m mFuel not reaching fuel injection system or carburettor (Chapter 4).
m mIgnition components damp or damaged (Chapter 5).
m mFuel injector stuck open (Chapter 4).
m mWorn, faulty or incorrectly-gapped spark plugs (Chapter 1).
m mBroken, loose or disconnected wiring in the starting circuit
(Chapter 5).
m mLoose distributor mounting bolts causing ignition timing to wander
(Chapters 1 and 5).
m mBroken, loose or disconnected wires at the ignition coil, or faulty
coil (Chapter 5).
Engine hard to start when cold
m mBattery discharged (Chapter 1).
m mFuel system malfunctioning (Chapter 4).
m mInjector(s) leaking or carburettor automatic choke faulty (Chap-
ter 4).
m mDistributor rotor carbon-tracked (Chapter 5).
Engine hard to start when hot
m
mAir filter element clogged (Chapter 1).
m mFuel not reaching the fuel injection system or carburettor (Chap-
ter 4).
m mCorroded battery connections, especially earth (negative)
connection (Chapter 1).
Starter motor noisy or excessively-rough in
engagement
m mPinion or flywheel gear teeth worn or broken (Chapter 5).
m mStarter motor mounting bolts loose or missing (Chapter 5).
Engine starts, but stops immediately
m
mLoose or faulty electrical connections at distributor, coil or
alternator (Chapter 5).
m mInsufficient fuel reaching the fuel injector(s) or carburettor
(Chapters 1 and 4).
m mDamaged fuel injection system speed sensors (Chapter 5).
m mFaulty fuel injection relays (Chapter 5).
Oil puddle under engine
m
mOil sump gasket and/or sump drain plug seal leaking (Chapter 2).
m mOil pressure sender unit leaking (Chapter 2).
m mValve cover gaskets leaking (Chapter 2).
m mEngine oil seals leaking (Chapter 2).
Engine idles erratically
m
mVacuum leakage (Chapter 4).
m mAir filter element clogged (Chapter 1).
m mFuel pump not delivering sufficient fuel to the fuel injection system
or carburettor (Chapter 4).
m mLeaking head gasket (Chapter 2).
m mTiming belt/chain and/or sprockets worn (Chapter 2).
m mCamshaft lobes worn (Chapter 2).
m mFaulty charcoal canister, where fitted (Chapter 6). This Section provides an easy-reference guide to the more
common problems which may occur during the operation of your
vehicle. These problems and their possible causes are grouped under
headings denoting various components or systems, such as Engine,
Cooling system, etc. They also refer you to the Chapter and/or
Section which deals with the problem.
Remember that successful fault diagnosis is not a mysterious
black art practised only by professional mechanics. It is simply the
result of the right knowledge combined with an intelligent, systematic
approach to the problem. Always work by a process of elimination,
starting with the simplest solution and working through to the mostcomplex - and never overlook the obvious. Anyone can run the fuel
tank dry or leave the lights on overnight, so don’t assume that you are
exempt from such oversights.
Finally, always establish a clear idea of why a problem has
occurred, and take steps to ensure that it doesn’t happen again. If the
electrical system fails because of a poor connection, check all other
connections in the system to make sure that they don’t fail as well. If a
particular fuse continues to blow, find out why - don’t just renew one
fuse after another. Remember, failure of a small component can often
be indicative of potential failure or incorrect functioning of a more
important component or system.
Engine