Camshaft Assembly Oil Seal Replacement

Overview

This procedure outlines the steps to replace the camshaft assembly oil seals and rear cam housing gasket on all Porsche 944 variants with an 8-valve engine, covering models from 1983 to 1988. Replacing these seals prevents oil leaks from the camshaft housing, ensuring proper engine performance and longevity. The process involves removing the timing belt, camshaft sprocket, and distributor housing to access and replace the seals, followed by reassembly and belt tensioning. This guide addresses differences between pre-1985.5 (1983–1985) and 1985.5 onwards (1986–1988) models, particularly in timing belt tensioning mechanisms.

Pink and blue text represent links to additional resources, tools, parts, and partner websites.

Tools Required

• Jack stands
• Floor jack
• Metric socket set
• Metric wrench set
• Timing Belt Tension Tool (P9201)
• Flywheel Lock Tool (P9206)
• Balance Shaft Pin Spanner (P9200) or equivalent (if removing balance shaft sprockets)
• Gear puller (if removing crankshaft gear)
• 3.175mm (1/8 inch) hex key
• 10mm (3/8 inch) Cheesehead tool
• 31.75mm (1-1/4 inch) open-end or combination wrench

Parts Required

• Front Main Camshaft Seal (Pre-85.5, engines up to #43F 06994 M/T or #43F 21202 A/T): 999 113 282 40 (30 x 47 mm)
• Front Main Camshaft Seal (85.5 Onwards): 999 113 349 40 (32 x 40 mm)
• Rear Distributor Housing O-Ring: 999 701 602 40 (50 x 5 mm)
• Rear Distributor Housing Seal (Small): 928 105 184 00
• Spacer Mylar Seal: 944 105 321 00
• Rear Cam Housing Cover Gasket: 928 105 189 02

Required Additional Procedures

Steps in these procedures are required to complete this process:

• Camshaft and Balance Shaft Belt Removal
• Camshaft and Balance Shaft Belt Installation
• Camshaft and Balance Shaft Belt Tension – Checking and Adjusting
• Flywheel Lock Installation
• Locating and Setting Engine to Top Dead Center (TDC), Cylinder 1
• Distributor Cap and Rotor Replacement
• Air Filter Housing and Air Flow Sensor – Removal and Installation

Step-by-Step Procedure

Step 1: Prepare the Vehicle

1. Disconnect the negative battery lead to prevent electrical shorts.
2. Follow this link to ensure this step – Air Filter Housing and Air Flow Sensor – Removal and Installation – is followed accurately to remove the air filter housing and air flow sensor.
3. Raise the vehicle using a floor jack and secure it on jack stands for safe access to the engine bay.

Step 2: Remove Accessory Belts and Covers

4. Loosen and remove the alternator and power steering belts by adjusting their tensioners.
5. Remove the front timing belt covers to access the camshaft sprocket and timing belt.

Step 3: Remove Distributor Components

6. Follow this link to ensure this step – Distributor Cap and Rotor Replacement – is followed accurately to remove the distributor cap and rotor.
7. Remove the front distributor housing cover to access the camshaft sprocket assembly.

Step 4: Detension the Timing Belt

8. 8. Follow this link to ensure this step – Camshaft and Balance Shaft Belt Removal – is followed accurately to prepare for timing belt removal.

For Pre-85.5 models:

• Loosen the camshaft tensioning roller lock nut using a 31.75mm (1-1/4 inch) wrench. Turn the tensioning roller nut clockwise to release timing belt tension. Hold the flats on the tensioner roller with an open-end wrench to provide counter-torque and prevent stress on the tensioner stud.

For 85.5 Onwards models:

• Locate the spring tensioner’s front plate (triangular shape). Loosen, but do not remove, the locknut and bolt on the side near the tensioning spring. Push down on the tensioner lever arm (or use a Balance Shaft Pin Spanner, P9200) to compress the spring, then tighten the locking bolt and nut to hold it.

8. Slide the timing belt off the camshaft sprocket carefully, ensuring the sprocket does not rotate significantly.

Step 5: Remove Camshaft Sprocket Components

10. Remove the M5 x 10 mm bolt (using a 10mm socket or wrench) securing the ignition rotor connector in the retaining collar’s recess. Pull the connector straight out; apply heat to the collar’s exterior if it’s stuck.
11. Locate the M10 x 65 mm bolt (cheesehead or hex) in the retaining collar. If it’s a hex bolt, replace it with a cheesehead bolt (torque spec: 65–70 Nm / 48–52 ft-lbs vs. 45 Nm / 33 ft-lbs for hex).
12. Insert a 10mm (3/8 inch) Cheesehead tool or 3.175mm (1/8 inch) hex key into the bolt. Tap the tool with a hammer to “wake up” the bolt and prevent stripping.
13. Hold the retaining collar’s flats with a 31.75mm (1-1/4 inch) combination wrench (closed end preferred) at a slight angle due to the rear distributor housing lip. Have a second person hold the wrench while you loosen the cheesehead bolt to prevent camshaft rotation (which could cause valve-piston contact).
14. Remove the M10 x 65 mm bolt, then slide the retaining collar and camshaft sprocket straight off the camshaft, avoiding rotation due to the woodruff key.
15. Remove the woodruff key from the camshaft slot using needle-nose pliers or diagonal cutters.

Step 6: Remove Rear Distributor Housing

16. Remove the three M6 bolts securing the rear distributor housing to the camshaft housing using a 10mm (3/8 inch) socket or wrench.
17. Slide the rear distributor housing off the camshaft. If the spacer (Figure 1, 20) comes with it, note the mylar seal (Figure 1, 23) on the camshaft end for replacement. If the spacer remains, slide it off and replace the seal.

Step 7: Replace Seals

18. Apply a thin layer of engine oil or bearing grease to the new seals before installation.
19. Install the front main camshaft seal (999 113 282 40 for Pre-85.5 or 999 113 349 40 for 85.5 Onwards) into the front of the rear distributor housing.
20. Install the large O-ring (999 701 602 40) and small round seal (928 105 184 00) into the back of the rear distributor housing to seal against the camshaft housing.
21. Install the mylar seal (944 105 321 00) onto the camshaft end if replacing the spacer.
22. Apply oil or grease to the seals post-installation to ensure proper seating.

Step 8: Reinstall Rear Distributor Housing

23. Slide the rear distributor housing with new seals onto the camshaft.
24. Install the three M6 retaining bolts and torque to 8 Nm (6 ft-lbs) using a 10mm (3/8 inch) socket or wrench.

Step 9: Reassemble Camshaft Sprocket

25. Insert the woodruff key into the camshaft slot.
26. Slide the camshaft sprocket and retaining collar onto the camshaft, aligning with the woodruff key.
27. Install the M10 x 65 mm cheesehead bolt into the retaining collar and torque to 65–70 Nm (48–52 ft-lbs) using a 10mm (3/8 inch) Cheesehead tool. If using a hex bolt, torque to 45 Nm (33 ft-lbs).
28. Apply Loctite to the M5 x 10 mm connector retaining bolt, insert it into the retaining collar, and tighten using a 10mm (3/8 inch) socket or wrench.

Step 10: Reinstall Timing Belt and Verify TDC

29. Follow this link to ensure this step – Locating and Setting Engine to Top Dead Center (TDC), Cylinder 1 – is followed accurately to verify the crankshaft is at TDC.
30. Align the camshaft sprocket to TDC using the scribe mark on the sprocket and the mark on the rear distributor housing.
31. Install the timing belt onto the camshaft sprocket, ensuring no slack between the camshaft sprocket and crankshaft gear.
32. Follow this link to ensure this step – Camshaft and Balance Shaft Belt Installation – is followed accurately for belt installation.
33. Follow this link to ensure this step – Camshaft and Balance Shaft Belt Tension – Checking and Adjusting – is followed accurately to tension the belt.

Step 11: Replace Rear Cam Housing Gasket

34. If equipped with a TDC sensor, remove the 10mm bolt securing the electrical connector’s retaining strap to the rear engine lifting ring and move the connector aside.
35. Remove the three M6 x 22 mm bolts securing the lifting ring and rear cam housing cover using a 10mm (3/8 inch) socket or wrench.
36. Apply a thin coat of bearing grease to both sides of the new rear cam housing cover gasket (928 105 189 02).
37. Position the gasket onto the rear cam housing cover, then install the cover and lifting ring onto the cam housing using the three M6 x 22 mm bolts.
38. Torque the bolts to 8 Nm (6 ft-lbs) using a 10mm (3/8 inch) socket or wrench.

Step 12: Final Reassembly

39. Reinstall the front timing belt covers.
40. Reinstall the alternator and power steering belts, adjusting their tensioners as needed.
41. Follow this link to ensure this step – Air Filter Housing and Air Flow Sensor – Removal and Installation – is followed accurately to reinstall the air filter housing and air flow sensor.
42. Reconnect the negative battery lead.
43. Lower the vehicle from the jack stands using the floor jack.

Post Procedure Checklist

• Check for oil leaks around the camshaft housing and rear cam housing cover after running the engine for 5 minutes.
• Verify the timing belt tension is correct by rechecking with the Timing Belt Tension Tool (P9201).
• Ensure the engine runs smoothly at idle and during a test drive of 5 miles (8 km).
• Confirm the camshaft sprocket and crankshaft remain aligned at TDC after reassembly.
• Inspect the distributor housing seals for proper seating and no leaks.

Sources

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