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Camshaft Timing chain1
Timing chains, removing
(M52 TU and M54 engines)
Camshaft timing chain removal requires that the oil pan be re-
moved. See
119 Lubrication System. Also required is re-
moval of the VANOS control
unit and disassembly of the
intake and exhaust camshaft sprocket assemblies as de-
scribed earlier in this repair group.
Special BMW
service tools are needed for timing chain re-
moval and installation. The special tools assure proper timing
of the valvetrain. Precise
marlts to set the timing on the cam:
shafts are not provided for reassembly. Read the procedures
through before beginning the job.
CA
UTION-
If the camshafts are not properly timed, the pistons can con-
tact the valves.
- D~sconnect negative (-) cable from battery.
CAUTION-
* Disconnecting the battery may erase fault code@) stored in
control module memory. Check for fault codes using spe-
cial
BMW diagnostic equipment.
Prior to disconnecting the battery, read the battery dis-
connection
cautfons given in 001 General Cautions
and
Warninqs.
- Remove VANOS control unit. See VANOS control unit, re-
moving
(M52 TU and M54 engines).
Remove sealing plug from crankcase below starter and se-
cure crankshaft with
BMW special tool ll 2 300.
Drain engine cooling system. See 170 Radiator and Cool-
ing System.
Remove belt driven cooling fan, fan shroud, and thermostat
housing. See
170 Radiator and Cooling System.
Remove drive belts. See
020 Maintenance.
NOTE-
Mark direction of belt rotation if reusing belt.
- Remove water pump pulley fasteners and pulley.
- Drain engine oil and remove oil pan as described in 119
Lubrication System.
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170-8
I Radiator and Cooling System
Common cooling system faults can be grouped into one of 4
categories:
Cooling system
lealts
Poor coolant circulation
Radiator cooling fan faults
Electrical/electronic faults
Cooling system inspection
- Check that coolant pump drive belt tensioner is functioning
properly and that belt tension is correct. Belt tensioner sys-
tems for the different models are shown in
020 Maintenance.
- Check condition of coolant pump drive belt.
- Checlc coolant hoses for cracks or softness. Checlc clamps
for looseness. Check coolant level and check for evidence of
coolant
lealts from engine.
- Check that radiator fins are not blocked with dirt or debris.
Clean radiator using low-pressure water or compressed air.
Blow outward, from engine side out.
- To check coolant pump:
Remove mechanical cooling fan. See Mechanical
(vis.
cous clutch) cooling fan, removing and installing.
Remove drive belt from coolant pump pulley. See
020
Maintenance.
Firmly grasp opposite sides of pulley and check for play in
all directions.
Spin pulley and check that shaft runs smoothly without
play.
NOTE-
The coolant provides lubrication for the pump shaft, so an oc-
casional drop of coolant
lealing from the pump is acceptable.
If coolant drips steadily from the vent hole, replace the pump.
- At normal engine operating temperature, cooling system is
pressurized. This raises boiling point of coolant.
Leaks may
prevent system from becoming pressurized. If visual evi-
dence is inconclusive, pressure test cooling system as de-
scribed later to help pinpoint hard-to-find leaks.
- If cooling system is full of coolant and holds pressure:
- Use an appropriate scan tool to interrogate engine control
module (ECM) for radiator fan or DME control circuit faults.
Checlc for loose or worn drive belt.
0 Test for failed thermostat or coolant pump impeller. Some
pumps may be fitted with plastic impellers.
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.," --
Radiator and Cooling System --- 1
insert two M6 screws (arrows) in tapped bores and tighten
uniformly until pump is free from timing chain cover (thermo-
stat and hoses have been removed for purposes of visual
clarity).
Installation is reverse of removal, noting the following:
Be sure to replace sealing O-ring and gaskets.
Coat O-ring with water-based lubricant during installation.
Refill with coolant. See Coolant, draining and filling
(6-
cylinder models).
Tightening torques
-
Coolant pump to timing chain 10 Nm (89 in-lb)
cover
Coolant pump pulley to coolant
10 Nm (89 in-lb
pump
Engine block drain plug to block 25 Nm (1 8 It-lb)
Radiator drain plug to radiator 2 - 3 Nm (I8 - 27 in-lb)
Coolant pump, replacing (V-8 models)
I 1 < The engine coolant pump is mounted in the front of the en-
gine in ;he timing chain cover.
1. Thermostat housing
2. Thermostat
3. Thermostat sealing O-ring
4. Water pump
5. Water pump gasket
- Drain cooling system. See Coolant, draining and filling (V-
8 models).
- Remove cooling fan and fan shroud. See Mechanical (vis-
cous clutch) cooling fan, removing and installing.
- Remove engine drive belts: See 020 Maintenance.
NOTE-
Mark direction of drive belt rotation if reusing belt,
- Remove vibration dampener. See 117 Camshaft and Tim-
ing Chain.
- Disconnect mass air flow (MAF) sensor electrical harness
connector. Remove air intake duct together with
MAF sensor.
- Disconnect coolant hoses from thermostat housing and cool-
ant pump housing.
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Radiator and Coolina ~vsteml
- Disconnect thermostat and cooling system temperature sen-
sor plug connectors.
4 Remove thermostat housing fasteners and remove housing.
- Remove coolant pump pulley bolts and remove pulley from
pump.
Remove fasteners A and B (arrows).
NOTE-
* The coolant pump is retained to the block using different
length bolts.
0 Bolts A: M6 X 105 mm
0 Bolts 8: M6 X 35 mm
Slide coolant pump away from coolant pipes (arrows) while
being careful not to dislodge pipes from fittings at rear of en-
gine.
- Installation is reverse of removal, noting the following:
Replace all sealing O-rings and washers.
Coat O-rings with water-based lubricant during installation.
Fill system with coolant. See Coolant, draining and fill-
ing (6-cylinder models) or Coolant, draining and filling
(V-8 models).