944 Oil/Water Heat Exchanger Seal Replacement Procedure

by Kevin Gross

The following note was co-authored by Albert Broadfoot - my thanks to him!

Note that the 924S, 944, and 944S have an oil/water heat exchanger, while the 944 Turbo and 944S2 have instead an oil filter console that routes oil to an external radiator. This procedure applies to all 944-series cars as well as the 924S.


Identify the type of oil pressure relief valve on your car. There are four versions of the valve that Porsche has used. Two are obsoleted by two newer versions, so there are in fact only two versions that you need to be aware of.

model year





924S, 944, 944 Turbo





up to engine no.
43 H 01919 - manual
43 H 60384 - automatic




from engine no.
43 H 01920 - manual
43 H 60385 - automatic



944, 944S, 944 Turbo-




924S, 944, 944S, 944 Turbo, 944S2



Version A

In original production from 1982 - 86, a three-piece spring and piston oil pressure relief valve was used. In 1987, a one-piece version was introduced as a retrofit to early production cars. There does not seem to be any service bulletin which suggest the retrofit is recommended except where the original relief valve is not operating properly.

The following part numbers are relevant to servicing early production cars:







seal ring


alignment tool 9215


Version B

Porsche began producing model year 1987 engines in July '86. These engines received a new type of one-piece oil pressure relief valve. Unfortunately, in engines produced between July and October, the relief valve was not anit-corrosion treated. Porsche recommends that when servicing these engines, the oil pressure relief valve be replaced with the corrected, anti-corrosion treated part.

The affected engines are as follows. The second column has the first engine numbers in production that received the Version B, untreated valve. The third column indicates the first engines that received the corrected, treated valves.


engine number,
untreated valve

engine number,
treated valve

924S/944 manual

43 H 01920

43 H 05373

924S/944 automatic

43 H 60385

43 H 61268


42 H 00140

42 H 02847

944 Turbo

45 H 00086

45 H 01256

The following part numbers are relevant to servicing Version B relief valves:







seal ring


alignment tool 9262/1


Tool and Supplies

You'll need a 24 mm. open crowfoot socket to perform this procedure.

You'll also need the correct alignment tool described above. Some folks just use the oil pressure relief valve itself to do the alignment, but we recommend using the proper tool for better accuracy.


You'll need a kit with new style seals and a gasket for the housing ("console"). It costs roughly US$20.


The job takes about 45 to 90 minutes, once you have the car safely jacked.

  1. Remove plastic under-tray.

  2. Remove two 8 mm. bolts (13 mm. head) from upper right sway bar mount and pull it down.

  3. Remove oil pressure relief valve from oil cooler housing, using a 24 mm. socket.

  4. Remove oil pressure sending unit and wires. 24mm. crow's foot or wrench and 7 mm. wrench for one term. The other terminal pulls off.

  5. Remove two 6 mm. bolts (10mm head) from heat shield mounted on oil cooler using 10 mm. socket, 1/4" drive with a 2" extension.

  6. Remove four 8 mm. bolts (13 mm. head) from all sides of oil cooler housing. Remove oil cooler housing from engine with oil cooler inside.

  7. Remove oil cooler from oil cooler housing. Clean with part cleaner. Must be free of particulates!

  8. Remove old o-rings (eu! thats a touchy subject) from both sides of oil cooler and install new green Vicon o-rings. Reinstall cooler into clean (must be clean) housing after applying lube to o-rings.

  9. At opposite end of cooler install black o-ring rubber spacer (with grease) and reinstall cooler to block. Hold in place while reinstalling 8mm bolts (13mm head). Do not tighten all the way! Just barly snug down so the cooler can be moved from side to side.

  10. Install the alignment tool into the oil pressure relief valve's bore in the cooler housing. Tighten it snuggly into the engine block, aligning the housing with the block.

  11. Now tighten down the four 8 mm. (13 mm. head) bolts.

  12. Remove the alignment tool, install the oil pressure relief valve with a new o-ring and seal ring.

  13. Now reinstall heat shield, oil pressure sender and sway bar mount.

  14. Change oil, filter and flush coolant.

  15. Bleed cooling system using tall cut off funnel that fits snugly in res. and loosen 12 mm. head bleeder at top of coolant neck, pore fresh coolant into funnel untill a bubbles are gone from bleeder valve and tighten.

  16. Start your engines!