Balance Shaft Oil Seal Replacement – 2.5L NA

Overview

This procedure outlines the steps to replace the balance shaft oil seals on a Porsche 944 with an 8-valve engine, covering both pre-1985.5 (1983–1985) and 1985.5 onwards (1986–1988) models. It also includes instructions for resealing the balance shaft cover if needed. Replacing these seals is critical to prevent oil leaks and ensure proper engine lubrication, maintaining the performance and longevity of the balance shaft system.

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Tools Required

• Jack stands
• Floor jack
• Metric socket set
• Metric wrench set
• Porsche Timing Belt Tension tool (P9201)
• Flywheel Lock tool (P9206)
• Balance Shaft Pin Spanner tool (P9200) or equivalent
• Gear puller
• Seal puller
• Small screwdriver or probe
• Bearing grease
• Loctite 574 and velour roller (if balance shaft cover is removed)

Parts Required

• Balance shaft main seals (2, one for upper and one for lower shaft, ensure correct diameter): 944 101 111 00 (upper, larger diameter), 944 101 111 01 (lower, smaller diameter)
• Balance shaft support o-ring: 999 701 632 40
• Rear housing plug o-ring (if replaced): 999 701 633 40
• Thin plastic seal for balance shaft: 944 101 112 00
• Bearing cap-to-cover seal (85.5 Onwards, if cover removed): 944 101 113 00
• Loctite 574 (if balance shaft cover is removed)

Required Additional Procedures

Steps in these procedures are required to complete this process:

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

Step-by-Step Procedure

Step 1: Prepare the Engine and Remove Components

1. Follow this link to ensure this step – Flywheel Lock Installation – is completed accurately to secure the flywheel.
2. Follow this link to ensure this step – Locating and Setting Engine to Top Dead Center (TDC), Cylinder 1 – is completed accurately to align the engine.
3. Follow this link to ensure this step – Air Filter Housing and Air Flow Sensor – Removal – is completed to remove the air filter housing.
4. Follow this link to ensure this step – Balance Shaft Belt Removal – is completed to remove the camshaft and balance shaft belts, all rollers, tensioners, balance shaft sprockets, crankshaft gears, and rear timing cover.

Step 2: Disassemble Balance Shaft Components

5. Locate the woodruff key in the slot of the balance shaft and carefully remove it using a small screwdriver or probe.
6. Remove the three retaining bolts (8mm, 5/16 inch) securing the front balance shaft support using a metric socket or wrench.
7. Slide the front balance shaft support off the end of the balance shaft and set it aside.

Step 3: Remove Balance Shaft Cover (If Required)

8. If the balance shaft cover needs resealing or the rear plug o-ring requires replacement, remove the balance shaft cover bolts (8mm, 5/16 inch) and carefully detach the cover along with the rear plug.

For 85.5 Onwards models:
Ensure the bearing cap-to-cover seal (944 101 113 00) is replaced to maintain proper oil flow to the upper balance shaft bearing.

For Pre-85.5 models:
This step is not applicable, as the bearing cap is machined integral to the balance shaft cover.

Step 4: Remove and Replace Seals and O-Ring

9. Using a seal puller, carefully remove the main balance shaft seals from the front of the balance shaft support. If a seal puller is unavailable, slide a small screwdriver under the inside lip of the seal and gently pry it out.

Caution: The main balance shaft seals have a 1 mm difference in outside diameter. Use 944 101 111 00 for the upper shaft and 944 101 111 01 for the lower shaft to avoid leaks.

10. Remove the spacer from the balance shaft support.
11. Using a small screwdriver or probe, remove the large o-ring (999 701 632 40) from the balance shaft support.
12. Apply a thin coat of bearing grease to the o-ring groove in the balance shaft support, install a new o-ring (999 701 632 40), and apply a thin coat of bearing grease to the outside of the o-ring.
13. Apply a thin coat of bearing grease to the contact surfaces of the support spacer and install the spacer into the support housing.
14. Apply a thin coat of bearing grease to the sealing surfaces of the new main balance shaft seal (944 101 111 00 or 944 101 111 01) and slide it into the front of the support.
15. Tap the seal into place using a socket with a slightly smaller outside diameter than the seal to ensure a secure fit.

Step 5: Reinstall Balance Shaft Cover (If Removed)

16. If the balance shaft cover was removed, install a new o-ring (999 701 633 40) onto the rear housing plug and position the plug into the housing.
17. Apply a thin coat of Loctite 574 to the cover mating surface using a velour roller and position the cover onto the balance shaft housing.
18. Install the balance shaft cover retaining bolts (8mm, 5/16 inch) finger tight. Do not torque until the front support is installed.

For 85.5 Onwards models:
Install a new bearing cap-to-cover seal (944 101 113 00) to ensure proper lubrication of the upper balance shaft bearing.

Step 6: Reassemble Balance Shaft Components

19. Install the thin plastic seal (944 101 112 00) onto the end of the balance shaft.
20. Slide the front support (with spacer and seal installed) onto the balance shaft and into the front of the housing until fully seated.
21. Install the three front support retaining bolts (8mm, 5/16 inch) finger tight.
22. If the balance shaft cover was removed, torque the cover retaining bolts to the following specifications based on your model:

For Pre-85.5 models:
Lower Balance Shaft: 20 Nm (15 ft-lbs)
Upper Balance Shaft: 20 Nm (15 ft-lbs)

For 85.5 Onwards models:
Lower Balance Shaft: 20 Nm (15 ft-lbs)
Upper Balance Shaft: 20 Nm (15 ft-lbs)

23. Torque the front support bolts (8mm, 5/16 inch) to 20 Nm (15 ft-lbs).

Step 7: Reinstall and Tension Belts

24. Follow this link to ensure this step – Balance Shaft Belt Installation – is completed to install the balance shaft and camshaft belts.
25. Follow this link to ensure this step – Balance Shaft Belt Tension – Checking and Adjusting – is completed to properly tension the belts.
26. Follow this link to ensure this step – Balance Shaft Sprocket Installation and Alignment – is completed to align the balance shaft sprockets.

Post Procedure Checklist

• Check for oil leaks around the balance shaft seals and cover after running the engine for 5 minutes.
• Verify that the balance shaft and camshaft belts are properly tensioned using the Porsche Timing Belt Tension tool (P9201).
• Ensure no unusual noises (e.g., whining or grinding) come from the balance shaft area during engine operation.
• Inspect the torque of all bolts (20 Nm, 15 ft-lbs) to confirm they are secure.
• Drive the vehicle for 5 miles (8 km) and recheck for leaks or belt issues.

Sources

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