1999 BMW 525i low oil pressure

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Cylinder Head and valvetrain1
Hydraulic lifters, checking and replacing
Self-adjusting hydraulic lifters (A) keep the valve clearances
within a limited working range. Hydraulic lifters are sealed
units and require no maintenance. Section view of camshaft
(6) and valve with conical valve spring (C) shown.
Under some circumstances, such as a cold start, the cam fol-
lowers may emit noise. Hydraulic lifter noise is usually a
high-
pitched tapping or chattering noise. In most instances, this is
considered normal as long as the noise goes away in a few
minutes (maximum
20 minutes). If the noise does not go
away, either the lifter is faulty or the oil pressure to the lifter is
low. Hydraulic lifter replacement requires that the camshaft
first be removed.
NOTE-
Before checking hydraulic lifters, male sure engine oil is
fresh and at the proper level.
Sticky lifters can be the result of
sludge build up in the cylinder head and lifters.
- Run engine until it reaches normal operating temperature.
Shut off engine.
- Working inside luggage compartment, disconnect negative
battery cable.
CAUTION-
Prior to disconnecting battery cable, read the baltery dls-
connection cautions given In 001 General Cautions and
Warnings.
Disconnecting the battery may erase fault
code(s)
stored in control module memory Check for fault codes
4 Remove left and right interior ventilation duct (left side
shown):
Release plastic locking tab
(A) or release loclting tabs on
top of duct (later models).
Rotate duct counterclockwise to
unloclt from bulithead and
remove (arrow).

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Table d. Valve guide specifications
Specifications
All engines (1997-2002)
Valve guide wear, maximum 0.5 mrn (0.020 in)
(valve tilt clearance
measured
with new valve)
Valve guide inside diameter,
installed
(tolerance per IS0 allowance H7)
Standard 6.0 mm (0.236 in)
Oversize
1 6.1 mrn (0.240 in)
Oversize 2 6.2
mm (0.244 in)
Valve stem oil seals
The purpose of the valve stem oil seal is to prevent excess oil
from entering the combustion chamber. The sign of faulty
valve stem oil seals is excessive oil consumption and smoke
from the exhaust immediately after starting and during decel-
eration.
NOTE-
Valve stem oil seals should not be reused. If valves are re-
moved, new valve stem oil seals should be installed.
Valve stem oil seal replacement requires that the cylinder
head be disassembled and the valves removed as described
above under Valves, removing and installing.
NOTE-
BMW special tools are available to remove the valve stem oil
seals. As an alternative, standard valve seal removal tools
are available from most automotive parts stores.
Lubricate new seal and install using hand pressure only. Be
sure to install valve spring
seat(s) before installing seal.

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Camshaft Timing Chain
1 VANOS I 4 When engine is started, camshafts are in deactivated
camshaft
retarded Engine I i oil supply
position:
. lntalte camshaft is held in RETARDED position by oil
pressure.
Exhaust camshaft is held in ADVANCED position by
preload spring and oil pressure.
VANOS
Piston out
ECM Piston in Within 2
- 5
seconds (50 engine revolutions), the ECM begins
monitoring and controlling camshaft positions.
The Double VANOS system allows full variability of camshaft
timing up to the limits of the system. When the ECM detects
that the camshafts are in optimum position, the solenoids are
modulated at approximately 100
- 220 Hz to maintain oil pres-
sure on both sides of the actuator pistons to maintain timing.
In models with DME
MS 43.0 (model year2001 and newer),
the engine control module (ECM) detects camshaft position
before the engine starts, thereby adjusting camshaft timing
immediately upon start-up.
NOTE-
. VANOS system troubleshooting and diagnostics is best
accomplished using a scan tool.
. Diagnostic Trouble Codes (DTCs) pertaining to the
VANOS system are listed
in the following table. See also
OED On-Board Diagnostics.
Elevated oil temperatures can cause VANOS to deactivate.
Oil that is too thick (high viscosity) may cause
a DTC to be
set
in the ECM. If VANOS is deactivated (limp-home
mode), there will be a noticeable loss of power.
VANOS fault codes
BMW code P-code Fault description
19
PI529 VANOS solenoid valve activation,
exhaust
21
PI525 VANOS solenoid valve activation,
intake
103
PI519 VANOS faulty reference value
intake
104
PI520 VANOS faulty reference value
exhaust
105
PI522 VANOS stuck (Bank I) intake
106
PI523 VANOS stuck (Bank 2) exhaust

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11 9 Lubrication System
General ............................ 11 9-2
Special tools
......................... 11 9-2
..................... Engine lubrication 11 9-3
Troubleshooting .................... 11 9-3
................. Oil pressure. checking 11 9-4
...... Oil pressure warning system. testing 11 9-5
Crankshaft Rear Main Seal ......... .I1 9-6
Crankshaft rear main seal.
replacing (6-cylinder)
.................. 11 9-6
Crankshaft rear main seal. replacing (V-8)
. . 11 9-8
Engine Oil Pan .................... .I1 9-10
Oil pan. removing and
................. installing (6-cylinder) .I1 9-10
Lower oil pan. removing and
installing (V-8)
....................... 1 19-1 3
Upper oil pan. removing and
installing (V-8)
....................... 11 9-1 5
.......... Component Replacement 11 9-20
Oil pressure warning switch. replacing
.................. (6-cylinder and V-8) 11 9-20
Oil level warning switch. replacing
.................. (6-cylinder and V-8) 11 9-21
Oil pump. removing and
................. installing (6-cylinder) 11 9-22
Oil pump. removing and installing (V-8)
. . 11 9-24
..... Oil pressure relief valve (6-cylinder) 119-26
.......... Oil pressure
relief valve (V-8) 11 9-27

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11 9-2
Lubrication System
This repair group covers lubrication system troubleshooting
as well as oil pan removal and oil pump replacement.
In 6-cylinder models, removal of the oil pan requires the re-
moval of the exhaust system and some front suspension
components. Those procedures are fully covered in:
180 Exhaust System
210 Clutch
230 Manual Transmission
0 240 Automatic Transmission
310 Front Suspension
320 Steering and Wheel Alignment
NOTE-
Oil change procedure and oil filter replacement are covered
in
020 Maintenance.
CAUTIOG
V8 engines: The oil pump fasteners (including the sprocket
retaining nut) are known to vibrate loose. This can result in oil
starvation and engine failure. Be sure to check oil bolts and
nut tightness whenever the
oilpump is accessible. If any fas-
teners are found to be loose, remove them and reinstall with
Loctite
Band torque to specifications.
Special tools
The engine needs to be properly supported while the front
suspension
subframe is lowered to access the oil pan.
A standard oil pressure gauge may be used for measuring oil
pressure.
Engine support bracket
(Tool No, BMW 00 0 20012011202~2041208)
4 6-cylinder crankshalt rear main seal tools
(Tool No. BMW 00 5 50011
1 1 260)

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1 19-3
Lubrication System
V-8 crankshaft rear main seal tool
(Tool No. BMW
11 1 230)
I i 4 V-8 crankshaft rear main seal ouide
4 Adapter for BMW oil pressure gauge
(Tool No. BMW
11 4 050)
Engine lubrication
Oil pressure is generated by a gear-type pump bolted to the
bottom oi the engine block. The oil pump is chain driven off
the front of the crankshaft.
Table a. Engine oil capacity (includes oil filter replacement)
6-cylinder 6.5
liters (6.9
US qt)
V-8 7.5 liters (7.9 US qt)
The oil pressure warning system consists of an oil pressure
switch mounted in the oil circuit and an instrument
panel
warning light. Other saiety features include:
Q A filter bypass to provide lubrication should the oil filter be-
come clogged.
An oil pump pressure relief valve to prevent excessive sys-
tem pressure.
CAUTIOI\C
If the red oil pressure warning light comes on or flashes on
while driving, always assume that the oilpressure is low. Stop
the engine immediately and make arrangements to test oil
pressure.

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-
I Lubrication System - I
Oil pressure, checking
The oil pressure warning switch is located at the base of the
oil filter housing.
In 6-cylinder engines access to oil pressure warning switch
connector (arrow) is extremely restricted (intake manifold re.
moved for the purpose of illustration).
V-8 engine oil pressure warning switch (arrow) is at base of
oil filter housing on left engine compartment inner fender.
Oil pressure is tested by removing oil pressure switch and in-
stalling oil pressure gauge in its place.
Unscrew oil filter cap in order to allow engine oil to drain back
down into oil pan.
Disconnect harness connector from oil pressure switch and
remove switch.
NOJE-
Thoroughly clean around the oil pressure switch before
removing it.
Be prepared to catch leaking oil with a shop towel.
- Install pressure gauge in place of oil pressure switch,
- With gauge installed, start engine and allow to reach operat-
ing temperature. Check oil pressure. See Table b.
NOJE-
For the most accurate test results, the engine oil and filter
should be new. The oil should be the correct grade.
Table b. Engine oil pressure
At idle 0.5 bar (7 psi)
At elevated speed
6-cylinder engine 4.0 bar
(59 psi)
V-8 engine 4.5 bar (66 psi)

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. .- -
L
- --
- - -. - -- Lubrication ~~stern
- Remove pressure gauge and reinstall pressure switch with
new sealing washer.
Tightening torque
Oil pressure switch to oil filter housing 27 Nm (20 ft-lb)
If testing shows low oil pressure, one or more of the following
conditions may be indicated:
Worn or faulty oil pump or faulty pump pressure relief valve
Worn or damaged engine bearings
Severe engine wear
Any of these conditions indicate the need for major repairs.
Oil pressure warning system, testing
4 When the ignition is turned on, the oil pressure warning light
comes on. When the engine is started and the oil pressure
rises slightly, the oil pressure switch (arrow) contact opens
and the warning light goes out. Make sure the oil level is cor-
rect before making tests.
- Turn ignition switch on.
- Warning light on instrument panel must light up
- Remove connector from oil pressure switch.
Warning light on instrument panel must go out.
NOTE-
If the light does not go out, the wiring to the switch is most
likely grounded somewhere between the switch terminaland
the warning light See
ELE Electrical Wiring Diagrams for
electrical schematics.
- If warning light does not light when ignition is on, remove con-
nector from oil pressure switch and use a jumper wire to
ground connector terminal to a clean metal surface. The oil
pressure warning light should come on.
NOTE-
If there are two wires to the oil pressure switch, ground the
brown/green wire that carries the signal to the warning light.
- If the warning light comes on, check the switch as described
in the next step. If the warning light does not come on, the
wiring to the instrument cluster or to the light itself is faulty.