Instruments - Oil Pressure Gauge Reads With Engine OFF
REF. No. 18/37To: OUR MERCEDES-BENZ CAR DEALERS
DATE: June 1988
SUBJECT:
MODIFIED OIL PRESSURE RELIEF VALVE PISTON
ENGINES 102
As of April 1987 production a modified oil pressure relief valve piston was phased into production on the above mentioned engine. The modified piston has four enlarged dampening surfaces (arrow) through which the movement of the piston is less dampened and thereby eliminates pressure peaks in the oil circuit of a cold engine (Figure 1). The dimension across the flats, "A" is now 13 mm, previously 13.5 mm (Figure 1).
The piston is located behind the hex. socket plug (16) in the timing gear cover (Figure 2).
Install the modified piston if the seal for the oil filter element is pushed out or the oil pressure gauge continues to indicate an oil pressure of 3 bar with the engine turned off. When installing the modified piston, ensure that it moves freely in the timing gear cover.
Only the modified piston is available as a replacement part. The part number remains unchanged.
Note:
When installing a piston always measure dimension "A" (Figure 1).
Parts Information
In case of warranty:
Time Allowance
Refer to the latest Time Guide microfiche (Operation No. 18-5031)
Damage Code
18022 99 Piston, oil pressure relief valve, defective