Balance Shaft Sprocket Installation and Alignment Check

Overview

This procedure guides you through installing the balance shaft sprockets and checking their alignment on your Porsche 944 S2 with the 3.0L engine. Proper alignment is crucial to prevent vibrations, which can occur if the balance shaft belt slips, breaks, or if the sprockets are misinstalled—common issues after replacing the water pump or oil seals. This guide ensures your engine runs smoothly by correctly positioning the sprockets and verifying their alignment.

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Tools Required

• 10mm (3/8 inch) wrench
• 13mm wrench
• Torque wrench
• Heavy wire or small probe (if sprocket cover tabs are broken)

Parts Required

• Balance shaft sprocket (upper), 944 102 025 03
• Balance shaft sprocket (lower), 944 102 025 03
• Woodruff key (if replacement needed), N 012 708 2
• Sprocket retaining bolts (if replacement needed), 944 102 219 00

Required Additional Procedures

Steps in these procedures are required to complete this process:

• Locating and Setting Engine to Top Dead Center (TDC), Cylinder 1

Step-by-Step Procedure

Step 1: Install the Balance Shaft Sprockets

1. Locate the two slotted grooves on the inside of each balance shaft sprocket. One groove will fit onto a woodruff key on the balance shaft.
2. For the upper balance shaft (on the Porsche 944 S2 3.0L engine), find the groove marked with an “O” on the sprocket. Slide this groove onto the woodruff key on the upper shaft.
3. For the lower balance shaft, find the unmarked groove (the one without an “O”) on the sprocket. Slide this groove onto the woodruff key on the lower shaft. (Note: Misaligning this by using the “O” groove will cause a 180-degree error and severe vibration.)
4. Secure each sprocket with its retaining bolt. Tighten to 45 Nm (33 ft-lbs) using a torque wrench.

Step 2: Verify Sprocket Installation with Covers On

5. Install the balance shaft sprocket covers if not already in place. Each cover has round openings and one rectangular opening with a tab that fits into the groove without the woodruff key.
6. Check the upper sprocket: Look through the round openings on the cover. The “O” marking should be visible in one of these openings if installed correctly.
7. Check the lower sprocket: Look through the rectangular opening on the cover. The “O” marking should be visible here if installed correctly.
8. If the tabs on the covers are broken, remove the retaining bolts, lift the cover, and slide a heavy wire or small probe into each groove to locate the woodruff key. Confirm the “O” groove is on the upper shaft’s key and the unmarked groove is on the lower shaft’s key.

Step 3: Check Balance Shaft Alignment

9. Follow this link to ensure this step – Locating and Setting Engine to Top Dead Center (TDC), Cylinder 1 – of the process is followed accurately.
10. With the engine at TDC, inspect the upper balance shaft sprocket. The notch on its back lip should align with the notch on the rear timing belt cover (around the 1 o’clock position).
11. Inspect the lower balance shaft sprocket. The notch on its back lip should align with the raised tab inside the rear timing belt cover (around the 7 o’clock position).
12. If the notches don’t align perfectly (common in some cases), ensure neither sprocket is off by more than half a tooth. If misalignment exceeds one tooth, remove and reinstall the sprocket following Step 1.

Post Procedure Checklist

• Confirm both sprockets are secure and torqued to 45 Nm (33 ft-lbs).
• Check that the “O” marking is visible in the correct opening on each sprocket cover (round for upper, rectangular for lower).
• Verify alignment notches are within half a tooth of their marks at TDC.
• Start the engine and listen for abnormal vibrations, indicating possible misalignment.

Sources

• Clark’s Garage
• Pelican Parts
• Porsche 944 Workshop Manual, Volume 1
• Youtube