BMW 1989-1995 525i Service Manual page 146

119-2
LUBRICATION SYSTEM
Oil pressure switch locallons
• 525i, M20 engine beneath right engine mount
• 535i. M30 engine rear corn er of engine. left side
• 525i, M50, M60 engine oil filter housing
CAUTION-
Some oil may drain out as the oil pressure switch
is removed. Use a rag to soak up any spills and in-
stal/ the gauge as quickly as possible.
2. With the gauge installed. start the engine and check the
oil pressure. Oil pressure specifications are listed be-
low.
NOTE-
For the most accurate test resulls. the engine oil should
be new and of the correct grade.
Lubrication system specifications
• Oil pressure
at idle _ _ _. 0.5·2.0 bar (7-28 psi)
at maximum engine speed 4.0-5.0 bar (57-71psi)
3. If testing shows low oil pressure. one or more of the fol-
lowing conditions may be Indicated: 1) worn or faulty oil
pump 2) worn or faulty bearing s or 3) severe engine
wear. All of these conditions indicate the need for major
repairs.
To test oil pressure warning system
When the ignition is turned on. the oil pressure warning
light comes on. When the engine is started and the oil pres-
sure rises, the oil pressure switch opens and the warning light
goes out.
NOTE -
Make sure the oil level is correct before doing the tests
listed below.
1. Turn the ignition switch on. The warning light on the in-
strument panel should light up. Remove the connector
from the oil pressure switch. The light should go out
and the check control should display "O IL PRESS
SENSOR".
NOTE -
If the light does not go out, the wiring to the switch
is
most likely grounded somewhere between the switch
terminal and the warning light. See 600 Electrical Sys-
tem-General for electrical wiring troubleshooting in-
formation.
TROUBLESHOOTING
2. If the warning light does not light when the ignition is
on. remove the connector from the oil pressure switch
and use a jumper wire to ground the connector terminal
to a clean metal surface.
NOTE-
If the
warning light comes on. check the switch
as
de-
scribed in the next step. If the warning light does not
come on. the wiring circuit to the dash light
or
the light
itself is faulty.
3. To test the switch, connect an ohmmete r between the
terminal in the switch body and ground. With the engine
off, there should be continuity. With the engine running,
oil pressure should open the switch and there should
be no continuity. Replace a faulty switch.
WARNING -
Keep in mind that low oil pressure may be prevent-
ing the switch from turning the light out. If the light
remains on while the engine is running. check the
oil pressure as described above. Do not operate the
engine until the problem is corrected. The engine
may be severely damaged.
Tightening Torque
• Oil pressure switch
(lubricate threads) 40 Nm (29 fH b)
To test oil level sensor
The oil level sensor is similar in operation to the fuel level
sensor in the fuel tank. When the oil level falls below a safe
level. a warning is displayed in the check control module.
Check that the oil level is correct before testing the sensor.
The oil level sensor is mounted in the oil pan and contains
two switches . The static switch senses the oil level when the
engine is off and the ignition is on and the dynamic switch
senses the level when the engine is running.
1. Disconnect the negative (-) terminal from the battery.
2. Check that the oil level is correct on the dipstick.