Hydraulic Lifter - Noise
86porsche03Subject: Hydraulic Lifter Noise, 16 Valve Engine
Model
944S
Group
1
Part Identifier
15---
Number
8626
Dec. 19, 1986
When encountering complaints of hydraulic lifter noise, the following procedure should be used.
Step 1 (Do not remove head cover)
Check adjustment of mounting screw (Arrow B) for pressure reducing valve. With warm engine, loosen set screw and turn out a maximum of one turn. Exceeding one turn may cause mispositioning of pressure reducing valve in the cylinder head.
By hand, thread inset screw until stop is felt. From this position, loosen the set screw 1/8 of a turn (45 degrees). Start engine and let run at approximately 1500-2000 RPM for 20 minutes to bleed hydraulic valve system.
Step 2
If hydraulic lifter noise persists, replace the pressure reducing valve (Arrow A). Since the hydraulic valve lubrication system retains pressure, CAUTION must be used when removing the pressure reducing valve.
With the head cover removed, place a shop towel over the area of the pressure reducing valve and remove the set screw. This will prevent possible injury should the valve assembly suddenly pop out. After reassembly, bleed system as in Step 1.
Step 3
If after replacing the pressure reducing valve hydraulic lifter noise can still be heard, locate and remove suspect lifter(s) and check for damage. Replace parts as necessary.