Balance Shaft Belt Tension – Checking and Adjusting

Overview

This guide explains how to check and adjust the tension of the balance shaft belt on a Porsche 944 S2 with a 3.0L engine. Correct tension ensures the balance shafts run smoothly, reducing vibration and preventing belt failure. This procedure is specific to the balance shaft belt and does not cover the camshaft belt.

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Tools Required

• Jack stands
• Floor jack
• Metric socket set
• Metric wrench set
• Porsche Timing Belt Tension Tool (P9201)
• 24 mm (15/16 inch) wrench (for crankshaft pulley bolt)
• 0.5 mm feeler gauge (or Porsche Special Tool 9207)

Parts Required

• Balance shaft belt (18 mm wide, “new style”) – 944 102 219 03

Required Additional Procedures

Steps in these procedures are required to complete this process:

• Balance Shaft Belt Removal
• Balance Shaft Belt Installation

Step-by-Step Procedure

Step 1: Prepare the Vehicle and Access the Balance Shaft Belt

1. If this is being done to check tension only, use the needed steps in this procedure – Balance Shaft Belt Removal – to access the balance belt and sprockets.
2. If you have previously removed your balance belt, follow this link to ensure the needed steps – Balance Belt Installation – of this process are followed accurately.
3. Ensure the engine is at top dead center (TDC) by turning the crankshaft clockwise with a 24 mm (15/16 inch) wrench on the crankshaft pulley bolt until the “OT” mark aligns in the bell housing window.

Step 2: Determine the Required Belt Tension

4. Confirm you’re using the correct balance shaft belt for the S2. The Porsche 944 S2 uses the “new style” 18 mm wide belt (944 102 219 03), which requires a tension of 3.5 ± 0.5 on the Porsche Timing Belt Tension Tool (P9201).

Step 3: Loosen the Balance Belt Idler Roller

5. Locate the balance belt idler roller near the balance shaft sprockets.
6. Loosen the locknut on the balance belt idler roller using a metric wrench (typically 13 mm, depending on your socket set).
7. Move the idler roller away from the balance shaft belt so it doesn’t touch the belt during tension checking or adjustment.

Step 4: Check the Balance Shaft Belt Tension

8. An initial testing of the tension can be done by twisting the belt midway along the upper span using the thumb and forefinger. If the belt twists less than 180 degrees, it is too tight; If the belt twists more than 180 degrees, it is too loose.
9. Take the Porsche Timing Belt Tension Tool (P9201) and pull the lock pin to release the tension roller.
10. Align the drag needle with the gauge needle on the tool.
11. Install the tool on the balance shaft belt between the lower and upper balance shaft sprockets, ensuring the tensioning roller is on the toothed side of the belt.
12. Push the tensioning roller against the belt until the locking pin on the tool clicks into place.
13. Read the tension on the dial. For the S2’s 18 mm wide belt, it should be 3.5 ± 0.5.

Step 5: Adjust the Balance Shaft Belt Tension

14. If the tension isn’t within 3.5 ± 0.5, adjust it by turning the balance belt idler roller with a metric wrench while the tension tool is still in place (if you have a helper) or remove the tool, adjust, and recheck.
15. Repeat checking and adjusting until the tension reads between 3.0 and 4.0 on the tool.
16. Once the tension is correct, tighten the idler roller locknut to 45 Nm (33 ft-lbs). Hold the roller with a wrench to apply counter-torque and prevent the tension from changing while tightening.

Step 6: Set the Balance Belt Idler Roller Clearance

17. Adjust the balance belt idler roller so the gap between the roller and the belt at the lower balance shaft sprocket is 0.5 mm. Use a 0.5 mm feeler gauge to measure this clearance.
18. Tighten the idler roller locknut to 45 Nm (33 ft-lbs) while maintaining the 0.5 mm gap.

Post Procedure Checklist

• Double-check the balance shaft belt tension with the Porsche Timing Belt Tension Tool (P9201) to confirm it’s still within 3.5 ± 0.5.
• Ensure the idler roller clearance remains at 0.5 mm using a feeler gauge.
• Turn the crankshaft two full turns clockwise with a 24 mm (15/16 inch) wrench and verify the “OT” mark aligns at TDC in the bell housing window.
• Inspect the belt for any signs of wear, misalignment, or damage before reinstalling covers.

Sources

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