1988 BMW 3 SERIES Engin overhaul

file in a vice equipped with soft jaws, slip the
ring over the file, with the ends contacting the
file face, and slowly move the ring to remove
material from the ends. When performing this
operation, file only from the outside in(see
illustration).
6Excess end gap isn’t critical unless it’s
greater than 1.0 mm. Again, double-check to
make sure you have the correct rings for your
engine.
7Repeat the procedure for each ring that will
be fitted in the first cylinder and for each ring
in the remaining cylinders. Remember to keep
rings, pistons and cylinders matched up.
8Once the ring end gaps have been
checked/corrected, the rings can be fitted on
the pistons.
9The oil control ring (lowest one on the
piston) is usually fitted first. It’s normally
composed of three separate components.
Slip the spacer/expander into the groove(see
illustration). If an anti-rotation tang is used,
make sure it’s inserted into the drilled hole in
the ring groove. Next, refit the lower side rail.
Don’t use a piston ring refitting tool on the oil
ring side rails, as they may be damaged.
Instead, place one end of the side rail into the
groove between the spacer/expander and the
ring land, hold it firmly in place, and slide a
finger around the piston while pushing the rail
into the groove(see illustration). Next, refit
the upper side rail in the same manner.
10After the three oil ring components have
been fitted, check to make sure that both the
upper and lower side rails can be turned
smoothly in the ring groove.
11The middle ring is fitted next. It’s usually
stamped with a mark which must face up,
towards the top of the piston. Note:Always
follow the instructions printed on the ring
package or box - different manufacturers may
require different approaches. Do not mix up
the top and middle rings, as they have
different cross-sections.
12Make sure the identification mark is facing
the top of the piston, then slip the ring into the
middle groove on the piston (see illus-
tration 18.2). Don’t expand the ring any more
than necessary to slide it over the piston. Use
a proper ring-fitting tool if available; with care,
old feeler gauges can be used to prevent the
rings dropping into empty grooves.13Refit the top ring in the same manner.
Make sure the mark is facing upwards. Be
careful not to confuse the top and middle
rings.
14Repeat the procedure for the remaining
pistons and rings.
23 Intermediate shaft- refitting
5
1Clean the intermediate shaft bearing
surfaces and the pressed-in bearing sleeves
in the cylinder block.
2Lubricate the shaft, and slide it into the
block.
3Refit the two bolts that hold the retaining
plate to the block.
4The remainder of the parts are fitted in the
reverse order of removal.
24 Crankshaft- refitting and
main bearing oil clearance
check
4
1Crankshaft refitting is the first major step in
engine reassembly. It’s assumed at this point
that the engine block and crankshaft have
been cleaned, inspected, and repaired or
reconditioned.
2Position the block upside-down.
3Remove the main bearing cap bolts, and liftout the caps. Lay them out in the proper order
to ensure correct refitting.
4If they’re still in place, remove the original
bearing shells from the block and the main
bearing caps. Wipe the bearing surfaces of
the block and caps with a clean, lint-free
cloth. They must be kept spotlessly-clean.
Main bearing oil clearance
check
5Clean the back sides of the new main
bearing shells, and lay one in each main
bearing saddle in the block. If one of the
bearing shells from each set has a large
groove in it, make sure the grooved shell is
fitted in the block. Lay the other bearing from
each set in the corresponding main bearing
cap. Make sure the tab on the bearing shell
fits into the recess in the block or cap.
Caution: The oil holes in the
block must line up with the oil
holes in the bearing shell. Do not
hammer the bearing into place,
and don’t nick or gouge the bearing faces.
No lubrication should be used at this time.
6The flanged thrust bearing must be fitted in
the No 3 bearing cap and saddle in the M10
engine, in the No 6 bearing cap and saddle in
the M20 engine (see illustration), in the No 4
bearing cap and saddle in the M30 engine,
and in the No 4 bearing saddle only in the
M40 engine.
7Clean the faces of the bearings in the block
and the crankshaft main bearing journals with
a clean, lint-free cloth.
8Check or clean the oil holes in the
crankshaft, as any dirt here can go only one
way - straight through the new bearings.
9Once you’re certain the crankshaft is clean,
carefully lay it in position in the main bearings.
10Before the crankshaft can be permanently
fitted, the main bearing oil clearance must be
checked.
11Cut several pieces of the appropriate-size
Plastigage (they must be slightly shorter than
the width of the main bearings), and place one
piece on each crankshaft main bearing
journal, parallel with the crankshaft centreline
(see illustration).
12Clean the faces of the bearings in the
caps, and refit the caps in their respective
General engine overhaul procedures 2B•19
22.9b DO NOT use a piston ring refitting
tool when refitting the oil ring side rails22.9a Refitting the spacer/expander in the
oil control ring groove
24.11 Lay the Plastigage strips on the
main bearing journals, parallel to the
crankshaft centreline24.6 Refitting a thrust main bearing (note
the flanges) in the engine block bearing
saddle
2B

positions (don’t mix them up) with the arrows
pointing towards the front of the engine. Don’t
disturb the Plastigage.
13Starting with the centre main bearing and
working out toward the ends, progressively
tighten the main bearing cap bolts to the
torque listed in this Chapter’s Specifications.
On M10, M20 and M30 engines, tighten the
bolts in three stages. On the M40 engine,
tighten all the bolts initially to the Stage 1
torque, then angle-tighten them by the angle
given in the Specifications. Carry out the
angle-tightening on each bolt in one
controlled movement. Don’t rotate the
crankshaft at any time during the tightening
operation.
14Remove the bolts and carefully lift off the
main bearing caps. Keep them in order. Don’t
disturb the Plastigage or rotate the
crankshaft. If any of the main bearing caps are
difficult to remove, tap them gently from side-
to-side with a soft-face hammer to loosen
them.
15Compare the width of the crushed
Plastigage on each journal to the scale printed
on the Plastigage envelope to obtain the main
bearing oil clearance (see illustration). Check
the Specifications to make sure it’s correct.
16If the clearance is not as specified, thebearing shells may be the wrong size (which
means different ones will be required). Before
deciding that different shells are needed,
make sure that no dirt or oil was between the
bearing shells and the caps or block when the
clearance was measured. If the Plastigage
was wider at one end than the other, the
journal may be tapered (see Section 19).
17Carefully scrape all traces of the
Plastigage material off the main bearing
journals and/or the bearing faces. Use your
fingernail or the edge of a credit card - don’t
nick or scratch the bearing faces.
Final crankshaft refitting
18Carefully lift the crankshaft out of the
engine.
19Clean the bearing faces in the block, then
apply a thin, uniform layer of molybdenum
disulphide (“moly”) grease or engine oil to
each of the bearing surfaces. Be sure to coat
the thrust faces as well as the journal face of
the thrust bearing.
20Make sure the crankshaft journals are
clean, then lay the crankshaft back in place in
the block.
21Clean the faces of the bearings in the
caps, then apply engine oil to them.
22Refit the caps in their respective
positions, with the arrows pointing towards
the front of the engine.
23Refit the bolts finger-tight.
24Lightly tap the ends of the crankshaft
forward and backward with a lead or brass
hammer, to line up the main bearing and
crankshaft thrust surfaces.
25Tighten the bearing cap bolts to the
specified torque, working from the centre
outwards. On M10, M20 and M30 engines,
tighten the bolts in three stages to the final
torque, leaving out the thrust bearing cap
bolts at this stage. On M40 engines, tighten all
of the bolts in the two stages given in the
Specifications.
26On M10, M20 and M30 engines, tighten
the thrust bearing cap bolts to the torque
listed in this Chapter’s Specifications.
27On manual transmission models, fit a new
pilot bearing in the end of the crankshaft (see
Chapter 8).28Rotate the crankshaft a number of times
by hand to check for any obvious binding.
29The final step is to check the crankshaft
endfloat with a feeler gauge or a dial indicator
as described in Section 13. The endfloat
should be correct, providing the crankshaft
thrust faces aren’t worn or damaged, and new
bearings have been fitted.
30Fit the new seal, then bolt the housing to
the block (see Section 25).
25 Crankshaft rear oil seal-
refitting
3
1The crankshaft must be fitted first, and the
main bearing caps bolted in place. The new
seal should then be fitted in the retainer, and
the retainer bolted to the block.
2Before refitting the crankshaft, check the
seal contact surface very carefully for
scratches and nicks that could damage the
new seal lip and cause oil leaks. If the
crankshaft is damaged, the only alternative is
a new or different crankshaft, unless a
machine shop can suggest a means of repair.
3The old seal can be removed from the
housing with a hammer and punch by driving
it out from the back side (see illustration). Be
sure to note how far it’s recessed into the
housing bore before removing it; the new seal
will have to be recessed an equal amount. Be
very careful not to scratch or otherwise
damage the bore in the housing, or oil leaks
could develop.
4Make sure the retainer is clean, then apply
a thin coat of engine oil to the outer edge of
the new seal. The seal must be pressed
squarely into the housing bore, so hammering
it into place is not recommended. At the very
least, use a block of wood as shown, or a
section of large-diameter pipe (see
illustration). If you don’t have access to a
press, sandwich the housing and seal
between two smooth pieces of wood, and
press the seal into place with the jaws of a
large vice. The pieces of wood must be thick
enough to distribute the force evenly around
the entire circumference of the seal. Work
2B•20 General engine overhaul procedures
25.5 Lubricate the lip of the seal, and bolt
the retainer to the rear of the engine block25.4 Drive the new seal into the retainer
with a wooden block or a section of pipe, if
you have one large enough - make sure
the seal enters the retainer bore squarely25.3 After removing the retainer from the
block, support it on two wooden blocks,
and drive out the old seal with a punch and
hammer
24.15 Compare the width of the crushed
Plastigage to the scale on the envelope to
determine the main bearing oil clearance
(always take the measurement at the
widest point of the Plastigage); be sure to
use the correct scale - standard and
metric ones are included

slowly, and make sure the seal enters the bore
squarely.
5The seal lips must be lubricated with multi-
purpose grease or clean engine oil before the
seal/retainer is slipped over the crankshaft
and bolted to the block (see illustration). Use
a new gasket - no sealant is required - and
make sure the dowel pins are in place before
refitting the retainer.
6Tighten the retainer nuts/screws a little at a
time until they’re all snug, then tighten them to
the torque listed in the Specifications in
Chapter 2A.
26 Pistons/connecting rods-
refitting and big-end bearing
oil clearance check
4
1Before refitting the piston/connecting rod
assemblies, the cylinder walls must be
perfectly clean, the top edge of each cylinder
must be chamfered, and the crankshaft must
be in place.
2Remove the cap from the end of No 1
connecting rod (refer to the marks made
during removal). Remove the original bearing
shells, and wipe the bearing surfaces of the
connecting rod and cap with a clean, lint-free
cloth. They must be kept spotlessly-clean.
Connecting rod big-end bearing
oil clearance check
3Clean the back side of the new upper
bearing shell, then lay it in place in the
connecting rod. Make sure the tab on the
bearing fits into the recess in the rod. Don’t
hammer the bearing shell into place, and be
very careful not to nick or gouge the bearing
face. Don’t lubricate the bearing at this time.
4Clean the back side of the other bearing
shell, and refit it in the rod cap. Again, make
sure the tab on the bearing fits into the recess
in the cap, and don’t apply any lubricant. It’s
critically important that the mating surfaces of
the bearing and connecting rod are perfectlyclean and oil-free when they’re assembled for
this check.
5Position the piston ring gaps so they’re
staggered 120° from each other.
6Where applicable, slip a section of plastic
or rubber hose over each connecting rod cap
bolt.
7Lubricate the piston and rings with clean
engine oil, and attach a piston ring
compressor to the piston. Leave the skirt
protruding about 6 or 7 mm to guide the
piston into the cylinder. The rings must be
compressed until they’re flush with the piston.
8Rotate the crankshaft until the No 1
connecting rod journal is at BDC (bottom
dead centre). Apply a coat of engine oil to the
cylinder walls.
9With the mark or notch on top of the piston
facing the front of the engine, gently insert the
piston/connecting rod assembly into the No 1
cylinder bore, and rest the bottom edge of the
ring compressor on the engine block.
10Tap the top edge of the ring compressor
to make sure it’s contacting the block around
its entire circumference.
11Gently tap on the top of the piston with
the end of a wooden hammer handle (see
illustration)while guiding the end of the
connecting rod into place on the crankshaft
journal. Work slowly, and if any resistance is
felt as the piston enters the cylinder, stop
immediately. Find out what’s catching, and fix
it before proceeding. Do not, for any reason,
force the piston into the cylinder - you might
break a ring and/or the piston.
12Once the piston/connecting rod assembly
is fitted, the connecting rod big-end bearing
oil clearance must be checked before the rod
cap is permanently bolted in place.13Cut a piece of the appropriate-size
Plastigage slightly shorter than the width of
the connecting rod big-end bearing,
and lay it in place on the No 1 connecting rod
journal, parallel with the crankshaft centre-
line.
14Clean the connecting rod cap bearing
face, remove the protective hoses from the
connecting rod bolts, and refit the rod cap.
Make sure the mating mark on the cap is on
the same side as the mark on the connecting
rod.
15Refit the nuts/bolts, and tighten them to
the torque listed in this Chapter’s Specifica-
tions. On M10 and M30 engines, work up to
the final torque in three stages. Note:Use a
thin-wall socket, to avoid erroneous torque
readings that can result if the socket is
wedged between the rod cap and nut. If the
socket tends to wedge itself between the nut
and the cap, lift up on it slightly until it no
longer contacts the cap. Do not rotate the
crankshaft at any time during this operation.
16Undo the nuts and remove the rod cap,
being very careful not to disturb the
Plastigage.
17Compare the width of the crushed
Plastigage to the scale printed on the
Plastigage envelope to obtain the oil
clearance (see illustration). Compare it to the
Specifications to make sure the clearance is
correct.
18If the clearance is not as specified, the
bearing shells may be the wrong size (which
means different ones will be required). Before
deciding that different shells are needed,
make sure that no dirt or oil was between the
bearing shells and the connecting rod or cap
when the clearance was measured. Also,
recheck the journal diameter. If the Plastigage
was wider at one end than the other, the
journal may be tapered (see Section 19).
Final connecting rod refitting
19Carefully scrape all traces of the
Plastigage material off the rod journal and/or
bearing face. Be very careful not to scratch
General engine overhaul procedures 2B•21
26.17 Measuring the width of the crushed Plastigage to
determine the big-end bearing oil clearance (be sure to use the
correct scale - standard and metric ones are included)26.11 Drive the piston gently into the cylinder bore with the end of
a wooden or plastic hammer handle
2B
The piston rings may try to
pop out of the ring
compressor just before
entering the cylinder bore, so
keep some downward pressure on the
ring compressor

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

the alternator complete, or take it to an
automotive electrician, who may be able to
overhaul it. Note:On models up to 1986, a
blown ignition/no-charge warning light bulb
will prevent the alternator from charging. After
1987, a resistor is wired in parallel with the
warning light, in order to allow current to
bypass the light in the event of a broken circuit
(blown warning light).
15 Alternator-
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. Refer to
the information on page 0-7 at the front of
this manual before detaching the cable.
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
1Detach the battery negative cable.2Detach the electrical connectors from the
alternator, noting their locations for refitting
(see illustration). Note: On some models, it
may be necessary to remove the air cleaner
assembly and airflow meter to gain access to
the alternator.
3Loosen the alternator adjustment and pivot
bolts, and slip off the drivebelt (see Chap-
ter 1).
4Remove the adjustment and pivot bolts,
and separate the alternator from the engine.
Refitting
5If you are renewing the alternator, take the
old one with you when purchasing a new or
reconditioned unit. Make sure the new unit
looks identical to the old alternator. Look at
the terminals - they should be the same in
number, size and location as the terminals on
the old alternator. Finally, look at the identifi-
cation numbers - they will be stamped into the
housing, or printed on a tag attached to the
housing. Make sure the numbers are the same
on both alternators.
6Many new alternators do not come with a
pulley fitted, so you may have to transfer the
pulley from the old unit to the new one.
7Refitting is the reverse of removal.
8After the alternator is fitted, adjust the
drivebelt tension (see Chapter 1).
9Check the charging voltage to verify
proper operation of the alternator (see Sec-
tion 14).
16 Voltage regulator- renewal
1
1The voltage regulator controls the charging
system voltage by limiting the alternator
output. The regulator is a sealed unit, and isn’t
adjustable.
2If the voltmeter indicates that the alternator
is not charging (or if the ignition/no-charge
warning light comes on) and the alternator,
battery, drivebelt tension and electrical
connections seem to be fine, have theregulator checked by a dealer service
department or electrical specialist.
3Disconnect 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. Refer to
the information on page 0-7 at the front of
this manual before detaching the cable.
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.
Bosch alternator
4The voltage regulator is mounted externally
on the alternator housing. To renew the
regulator, remove the mounting screws (see
illustration)and lift it off the alternator (see
illustration). Note: Some Bosch alternators
have an integral voltage regulator which is part
of the brush assembly.
5Refitting is the reverse of removal. Note:
Before refitting the regulator, check the
condition of the slip rings(see illustration).
Use a torch and check for any scoring or deep
wear grooves. Renew the alternator if
necessary.
Motorola alternator
6Remove the alternator from the engine
compartment (see Section 15).
7Remove the rear cover and diode carrier,
remove the voltage regulator mounting
screws (see illustration)and lift the regulator
off the alternator body.
8Refitting is the reverse of removal.
17 Alternator brushes-
check and renewal
3
Caution: If the radio in your
vehicle is equipped with an anti-
theft system, make sure you
have the correct activation code
before disconnecting the battery.
5•10 Engine electrical systems
16.5 Use a torch to check the slip rings for
scoring or deep grooves16.4b The regulator can be withdrawn
easily on Bosch alternators. This type of
regulator is integral with the brush
assembly16.4a Remove the nuts and lift off the
small terminal protector from the
alternator cover, then remove the nuts and
the cover
15.2 Depending on how many accessories
the vehicle has, sometimes it’s easier to
remove the alternator from the brackets
first, and then turn it sideways to gain
access to the connections (arrowed) on
the rear of the alternator body

when the transmission selector lever is in Park
or Neutral.
Always detach the battery negative cable
before working on the starting system.
19 Starter motor-
in-vehicle check
2
Note:Before diagnosing starter problems,
make sure the battery is fully charged.
1If the starter motor does not turn at all when
the switch is operated, make sure that the
gear lever is in Neutral or Park (automatic
transmission) or, where applicable, that the
clutch pedal is depressed (manual
transmission).
2Make sure that the battery is charged, and
that all cables, both at the battery and starter
solenoid terminals, are clean and secure.
3If the starter motor spins but the engine is
not cranking, the overrun clutch in the starter
motor is slipping, and the starter motor must
be renewed.
4If, when the switch is actuated, the starter
motor does not operate at all but the solenoid
clicks, then the problem lies either in the
battery, the main solenoid contacts, or the
starter motor itself (or the engine is seized).
5If the solenoid plunger cannot be heard
when the switch is actuated, the battery is
faulty, the switch is defective, the fusible link
is burned-out (the circuit is open), or the
solenoid itself is defective.
6To check the solenoid, connect a jumper
lead between the battery (+) and the ignition
switch wire terminal (the small terminal) on the
solenoid. If the starter motor now operates,
the solenoid is OK and the problem is in the
ignition switch, starter inhibitor switch
(automatic transmission models), clutch
switch (some manual transmission models), or
the wiring.
7If the starter motor still does not operate,
remove the starter/solenoid assembly for
dismantling, testing and repair.
8If the starter motor cranks the engine at an
abnormally-slow speed, first make sure that
the battery is charged, and that all terminal
connections are tight. If the engine is partially-
seized, or has the wrong viscosity oil in it, it
will crank slowly.
9Run the engine until normal operating
temperature is reached, then disconnect the
coil HT lead from the distributor cap and earth
it on the engine.
10Connect a voltmeter positive lead to the
battery positive post, and connect the
negative lead to the negative post.11Crank the engine, and take the voltmeter
readings as soon as a steady figure is
indicated. Do not allow the starter motor to
turn for more than 10 seconds at a time. A
reading of 9 volts or more, with the starter
motor turning at normal cranking speed, is
normal. If the reading is 9 volts or more but
the cranking speed is slow, the solenoid
contacts are burned, there is a bad
connection, or the starter motor itself is faulty.
If the reading is less than 9 volts and the
cranking speed is slow, the starter motor is
faulty or the battery is responsible (defective
or discharged).
20 Starter motor-
removal and refitting
1
Note:If the starter motor is defective, it should
be renewed, or taken to an auto electrical
specialist for repair. Overhaul of the starter
motor is unlikely to be a practical proposition
for the home mechanic, even if spare parts are
available. However, the solenoid can be
renewed separately (see Section 21).
Removal
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. Refer to
the information on page 0-7 at the front of
this manual before detaching the cable.
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.
1Detach the battery negative cable.
2Raise the vehicle and support it securely on
axle stands.
3Clearly label the wires from the terminals onthe starter motor and solenoid, then
disconnect them. Note: On some models, it
may be necessary to remove the air cleaner
(see Chapter 4), coolant expansion tank (see
Chapter 3) and the heater hoses to gain
access to the top of the starter. Carefully label
any hoses or components that need to be
removed from the engine compartment, to
avoid confusion when reassembling.
4Unscrew the mounting bolts and detach the
starter (see illustrations).
Refitting
5Refitting is the reverse of removal.
21 Starter solenoid-
removal and refitting
1
Removal
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. Refer to
the information on page 0-7 at the front of
this manual before detaching the cable.
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.
2Remove the starter motor (see Section 20).
3Disconnect the cable from the solenoid to
the starter motor terminal.
4Remove the screws which secure the
solenoid to the starter motor.
5Detach the solenoid from the starter body.
6Remove the plunger and plunger spring.
Refitting
7Refitting is the reverse of removal.
5•12 Engine electrical systems
20.4b Withdrawing the starter motor from
the M40 engine20.4a Working under the vehicle, remove
the starter lower mounting bolt and nut
(arrowed)

friction surfaces of the brake shoes or
drums.
12Make sure the adjuster assembly is
properly engaged with its respective notch in
the handbrake lever.
13When refitting the automatic adjustment
mechanism, fit the lever on the shoe first (see
illustration), then hook the lower end of the
spring onto the lever and the upper end into
its hole in the front shoe (see illustration).
14When you’re done, the brake assembly
should look like this (see illustration). Now
proceed to the other brake.
15When you’re done with both brakes, refit
the brake drums.
16If the wheel cylinder was renewed (see
Note 2), bleed the hydraulic system as
described in Section 16.
17Depress the brake pedal repeatedly to
actuate the self-adjusting mechanism. A
clicking sound will be heard from the brake
drums as the adjusters take up the slack.
18Check the handbrake adjustment (Sec-
tion 11).
19Refit the wheels and bolts. Lower the
vehicle to the ground, and tighten the wheel
bolts to the torque listed in the Chapter 1
Specifications. Check the operation of the
brakes carefully before driving the vehicle in
traffic.
7 Master cylinder-
removal and refitting
3
Warning: Brake fluid is
poisonous. It is also an effective
paint stripper. Refer to the
warning at the start of Section 16.
Note: Although master cylinder parts and
overhaul kits are available for most models, we
recommend fitting a new or overhauled
master cylinder complete. It will take you more
time to overhaul the master cylinder than to
renew it, and you can’t even determine
whether the master cylinder is in good enough
condition to overhaul it until you have
dismantled it. You may very well find that itcan’t be overhauled because of its internal
condition.
Removal
1The master cylinder is connected to the
brake vacuum servo, and both are attached to
the bulkhead, located on the left-hand side of
the engine compartment (see illustration).
2Remove as much fluid as you can from the
reservoir with a syringe.
3Place rags under the line fittings, and
prepare caps or plastic bags to cover the
ends of the lines once they are disconnected.
Caution: Brake fluid will damage
paint. Cover all body parts, and
be careful not to spill fluid during
this procedure.
4Loosen the union nuts at the ends of the
brake lines where they enter the master
cylinder. To prevent rounding off the flats on
these nuts, a split ring (“brake”) spanner,
which wraps around the nut, should be used.
5Pull the brake lines away from the master
cylinder slightly, and plug the ends to prevent
dirt contamination and further fluid loss.
6Disconnect any electrical connectors at the
master cylinder, then remove the nutsattaching the master cylinder to the brake
servo. Pull the master cylinder off the studs,
and lift it out of the engine compartment.
Again, be careful not to spill fluid as this is
done. Discard the old O-ring (see illustration)
between the master cylinder and the servo
unit.
Warning: The O-ring should
always be renewed. A faulty O-
ring can cause a vacuum leak,
which can reduce braking performance
and cause an erratic idle.
Bleeding procedure
7Before fitting a new or overhauled master
cylinder, it should be bled on the bench.
Because it will be necessary to apply pressure
to the master cylinder piston and, at the same
time, control flow from the brake line outlets, it
is recommended that the master cylinder be
mounted in a vice. Use a vice with protected
jaws, and don’t clamp the vice too tightly, or
the master cylinder body might crack.
8Insert threaded plugs into the brake line
outlet holes. Tighten them down so that there
will be no air leakage past them, but not so
tight that they cannot be easily loosened.
9Fill the reservoir with brake fluid of the
recommended type (see “Lubricants, fluids
and capacities” in Chapter 1).
10Remove one plug, and push the piston
assembly into the master cylinder bore to
Braking system 9•9
6.14 When you get everything back
together, this is how it
should look! 6.13b . . . then hook the lower end of the
spring onto the lever as shown; stretch the
spring, and hook the upper end into its
hole in the handbrake shoe6.13a Refit the automatic adjuster lever
first - make sure it’s properly engaged with
the notch in the front end of the
adjuster mechanism . . .
7.6 Always renew the O-ring (1) - groove
arrowed - between the master cylinder and
the brake servo
7.1 To remove the master cylinder, unplug
the electrical connector (top arrow),
disconnect the brake fluid hydraulic line
fittings (lower right arrow, other fitting not
visible in this photo) and remove the two
master cylinder mounting nuts (lower left
arrow, other nut not visible in this photo) -
5-Series master cylinder shown, 3-Series
similar
9

the stop-light switch (see Section 13). Note:
On right-hand-drive models, the brake pedal
in on the right-hand side of the vehicle, and is
connected to the left-hand side by a cross-
shaft. The adjustment is carried out on the
pushrod at the left-hand side, but the
dimension is measured at the pedal on the
right-hand side.
14On 5-Series models, adjust the brake
pedal height and the stop-light switch (see
Section 13).
15Refit the master cylinder (see Section 7)
and attach the vacuum hose.
16Carefully test the operation of the brakes
before returning the vehicle to normal use
9 Hydraulic brake servo-
description, removal and
refitting
3
Warning: Brake fluid is
poisonous. It is also an effective
paint stripper. Refer to the
warning at the start of Section 16.
Description
1On 5-Series E28 (“old-shape”) models, a
hydraulic brake servo system is fitted. The
servo unit, located between the brake pedal
(left-hand-drive) or cross-shaft lever (right-
hand-drive) and the master cylinder, is
operated by hydraulic pressure generated by
the power steering pump. When the engine is
running, the power steering pump supplies
hydraulic pressure to a power flow regulator/
accumulator. The regulator/accumulator
stores and regulates the pressure to the
hydraulic brake servo. When you press the
brake pedal, the pressure in the servo helps
actuate the master cylinder, reducing pedal
effort.
2The hydraulic brake servo cannot be
overhauled; if it fails, a new one must be fitted.
Testing the system requires special tools, so
even fault diagnosis is beyond the scope of
the home mechanic. If the system fails, take it
to a dealer service department or other
qualified garage for repairs.
Removal and refitting
3With the engine off, discharge the hydraulic
accumulator by depressing the brake pedal
20 times or more.
4Remove the master cylinder (see Section 7).
5Clean the area around the return and
supply line fittings, then disconnect them.
Plug the lines, to prevent dirt from entering the
system, and to prevent further fluid loss.
Caution: Even a particle of dirt
can damage the servo, so be
extremely careful to prevent dirt
from entering the system while
the lines are disconnected.
6Working from inside the passenger
compartment, remove the lower left trim
panels above the brake pedal (left-hand-drive
models) or glovebox and trim (right-hand-drive models). On left-hand-drive models, also
disconnect the pedal return spring.
7Prise off the retaining clip, and disconnect
the pushrod from the brake pedal (see
illustration 8.9) or cross-shaft lever.
8Remove the four mounting nuts and
remove the brake servo (see illus-
tration 8.10).
9Refitting is the reverse of removal. Tighten
the hydraulic lines to the torque listed in this
Chapter’s Specifications. Note:Don’t try to
tighten these fittings without a torque wrench.
If they’re loose, they can leak, which can affect
system operation; if they’re tight, they can be
damaged, and they’ll also leak. You’ll need a
crowfoot-type split ring (“brake”) attachment
for your torque wrench to tighten the fittings
properly.
10When you’re done, bleed the brake
hydraulic system (Section 16) and adjust the
brake pedal travel and the stop-light switch
(see Section 13).
10 Handbrake cable(s)- renewal
2
1Peel back the boot at the base of the
handbrake lever, and remove the handbrake
cable adjusting nut (see illustration)which
also secures the cable to the handbrake lever.There are two cables - one for each rear wheel
- and a nut for each cable. On some models, it
may be necessary to remove the centre
console completely for access.
2Raise the vehicle and support it securely on
axle stands.
3Remove the rear brake drum (see Section 6)
or rear brake disc (see Section 5).
4On rear drum models, unhook the
handbrake cable from the lever on the rear
brake shoe (see Section 6). On rear disc
models, remove the handbrake shoes and the
actuator (see Section 12) and unhook the
handbrake cable from the actuator (see
illustrations).
5On rear drum models, pull the cable and
cable conduit (tube) out of the back of the
brake backplate, then detach the cable
conduit from the cable clips on the back of
the trailing arm (it’s easier to pull out the old
cable, and fit the new cable, with the conduit
straight instead of curved). On rear disc
models, it’s unnecessary to detach the cable
conduit from the brake backplate, but it’s a
good idea to detach the conduit from the clips
and guides securing it to the trailing arm, to
take some of the bend out of the conduit.
6Working from the wheel end of the cable
conduit, pull the cable out of the conduit (see
illustration).
7Lubricate the new cable with multi-purpose
grease, then insert it into the cable conduit
Braking system 9•11
10.1 Peel back the handbrake lever boot
and remove the relevant handbrake cable
adjusting nut (both arrowed)
10.6 Pull the cable out of its conduit;
before you refit the new cable, be sure to
lubricate it with multi-purpose grease10.4b . . . then remove the pin securing the
cable to the inner cam, and remove the
inner cam
10.4a To detach the handbrake cable from
the handbrake actuator on models with rear
disc brakes, pull on the outer cam and
disconnect it from the inner cam . . .
9