Engine - Droning Noise From External Oil Cooler Area
90porsche08 May 8, 1990Subject: Oil Pressure Relief Valve, Droning Noise
Model Group
944 S2 1
Part Identifier Number
1726 9012
ATTENTION: Service Manager/Service Technician
Models Affected: 944 S2 Model years 1989 (K) and 1990 (L)
Concern: Hydraulic noise (humming/droning) heard from the engine and/or the external oil cooler area at around 1600 rpm can be caused by the oil pressure relief valve.
Repair Information: A new oil pressure relief valve with offset relief bores (arrows Figure 1) can be installed. The amount of offset is slight (0.8 mm) and difficult to gauge by visual inspection. Therefore, the new version oil pressure relief valve is marked on the hex end with a blue paint dot (arrow Figure 2).
Parts Information: New Version Valve: PN 944 107 035 02
Former Version Valve: PN 944 107 035 01
Oil pressure relief valve PN 944 107 035 01 can still be used for twovalve engines from model year '87 and for 944S model years '87 and '88 (Refer to Technical Bulletin 8904, Group 1, Book F, page 29 for specific applications.)
Vehicle Information: The new version oil pressure relief valve is installed in production from engine number: 42 L 05160.