Oil Cooler – Seal Replacement – 2.5L NA

Overview

This procedure outlines the steps to replace the oil cooler seals on a Porsche 944 (8-valve engine) for pre-1985.5 and 1985.5 onwards models. Failing oil cooler seals can cause oil and coolant to mix, leading to a “milkshake” appearance in the coolant reservoir. Prompt replacement is critical to prevent coolant from entering the oil system, which could cause severe engine damage. This guide focuses on the specific steps for the 8-valve engine configuration, ensuring clarity for DIY enthusiasts.

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Tools Required

• Metric socket set
• Metric combination wrench set
• Thin head 24mm (15/16 inch) open end wrench
• Alignment tool 9262/1 (Pre-85.5, for oil pressure relief valve 944 107 035 02)
• Alignment tool 9215 (85.5 Onwards, for oil pressure relief valve 944 107 035 11)
• 10mm socket
• 13mm socket
• 13mm combination wrench

Parts Required

• Integral gasket: 944 107 147 03 (1)
• O-ring (cooler element): 999 707 043 40 (2, green style, for naturally aspirated models)
• Plastic washer: 944 107 154 00 (1)
• Rubber seal: 944 107 153 02 (1)
• Shim: 944 107 219 00 (as needed, 0.5mm thickness)
• Oil filter (no part number specified)

Required Additional Procedures

Steps in these procedures are required to complete this process:

• Cooling System Draining, Filling, and Venting
• Oil Pressure Relief Valve Information

Step-by-Step Procedure

Step 1: Prepare the Vehicle

1. Raise the vehicle and secure it on jack stands.
2. Remove the belly pan to access the oil cooler area.

Step 2: Disconnect Components

3. Using a 13mm socket and ratchet and 13mm combination wrench, loosen the exhaust headers and move them back to clear the workspace. Complete removal is optional but simplifies access.
4. Remove the oil filter by hand or with an oil filter wrench.
5. Disconnect the wires from the oil pressure sending unit.
6. Using a thin head 24mm (15/16 inch) open end wrench, remove the oil pressure sending unit.
7. Remove the oil pressure relief valve.

Step 3: Drain Coolant and Remove Heat Shield

8. Follow the Cooling System Draining, Filling, and Venting procedure to drain the coolant from the vehicle. Follow this link to ensure this step – Cooling System Draining, Filling, and Venting – is followed accurately.
9. Using a 10mm socket or 10mm combination wrench, remove the heat shield above the oil cooler housing.

Step 4: Remove Oil Cooler Housing

10. Using a 13mm socket or 13mm combination wrench, remove the bolts securing the oil cooler housing.
11. Carefully remove the oil cooler housing and cooler element. The seals may stick to either the housing or the engine block.

Note: Some vehicles have three separate seals (older style), while others use a single integral gasket with all three seals combined. Check your setup to confirm.

Step 5: Replace Seals

12. Remove all old seals from the cooler housing, engine block, and cooler element.
13. Install two new o-rings (999 707 043 40) on both nozzles of the cooler element.

14. Install the plastic washer (944 107 154 00) between the cooler element and cooler housing, then slide the element into the housing.

15. Lay a straight edge across the top of the cooler housing next to the cooler element guide boss. Measure the distance between the boss lip and the straight edge (should be 0 ± 0.25 mm). Do not install the gasket before measuring. Add shims (944 107 219 00) as needed to achieve this measurement.

16. Install a new rubber seal (944 107 153 02) in the groove on the engine block. Apply a light coat of grease to hold it in place during assembly.

17. Install a new integral gasket (944 107 147 03) on the engine block. If your kit has three separate seals, use light grease to hold them in place.

Step 6: Reinstall Oil Cooler Housing

18. Bolt the assembled oil cooler housing to the engine block using a 13mm socket or wrench. Do not fully tighten the bolts yet.

For Pre-85.5 models:

• Use alignment tool 9262/1 for oil pressure relief valve 944 107 035 02. Follow this link to ensure this step – Oil Pressure Relief Valve Information – is followed accurately.

For 85.5 Onwards models:

• Use alignment tool 9215 for oil pressure relief valve 944 107 035 11. Follow this link to ensure this step – Oil Pressure Relief Valve Information – is followed accurately.

19. Insert the appropriate alignment tool into the oil pressure relief valve opening to align the housing.
20. Torque the oil cooler housing bolts (M8) to 20 Nm (15 ft-lbs).
21. Remove the alignment tool and install the oil pressure relief valve. Torque to 45 Nm (33 ft-lbs).

Step 7: Reinstall Components

22. Install the oil pressure sending unit and torque to 35 Nm (26 ft-lbs).
23. Reconnect the electrical wires to the oil pressure sending unit.
24. Install the heat shield above the oil cooler housing using a 10mm socket or wrench. Torque the bolts (M6) to 8 Nm (6 ft-lbs).
25. Apply a light coat of oil to the seal of a new oil filter and install it. Tighten to 20 Nm (15 ft-lbs).
26. Reinstall the exhaust headers using a 13mm socket and wrench.

Step 8: Flush and Refill Cooling System

27. If a “milkshake” appearance was present in the coolant reservoir, thoroughly flush the cooling system. Follow this link to ensure this step – Cooling System Draining, Filling, and Venting – is followed accurately.
28. After flushing, fill and vent the cooling system using the Cooling System Draining, Filling, and Venting procedure.

Step 9: Check Oil System

29. If coolant may have entered the oil system, change the engine oil, run the engine until warm, then change the oil and install a new filter.

Step 10: Final Steps

30. Reinstall the belly pan.
31. Lower the vehicle from the jack stands.

Post Procedure Checklist

• Check for coolant or oil leaks around the oil cooler housing.
• Verify the oil pressure sending unit is functioning by checking the dashboard gauge.
• Inspect the coolant reservoir for any signs of oil contamination after running the engine.
• Ensure all tools and debris are removed from the work area.
• Confirm the exhaust headers are securely fastened and not leaking.

Sources

• Clark’s Garage
• Pelican Parts
• Porsche 944 Workshop Manuals
• YouTube