Balance Shaft Belt Tension – Checking and Adjusting – 2.5L NA

Overview

Checking and adjusting the balance shaft belt tension on the Porsche 944 (8-valve engine) ensures the belt operates correctly, reducing engine vibrations and preventing premature wear or failure. Proper tension is critical for engine longevity, especially during scheduled maintenance intervals (e.g., 2,000 miles / 3,218 km, 15,000 miles / 24,140 km). This guide provides a step-by-step procedure for checking and adjusting the balance shaft belt tension, tailored to pre-1985.5 (1983–1985.5) and 1985.5 onwards (1985.5–1988) models, based on standard practices and cross-referenced with Porsche 944 resources. Accessing the balance shaft belt may require partial exposure of the timing belt area.

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

Tools Required

• 17mm (11/16 inch) socket and ratchet
• 19mm (3/4 inch) socket
• 13mm (1/2 inch) wrench (Pre-85.5 only)
• Torque wrench (capable of 20–50 Nm / 15–37 ft-lbs)
• Balance shaft belt tension gauge (recommended for precise tensioning)
• Flathead screwdriver

Parts Required

• Tensioner Stud (Pre-85.5): 944 102 216 01 (1984.5–1986; replace if damaged during adjustment)

Step-by-Step Procedure

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

1. Park the Porsche 944 on a flat surface, engage the parking brake, and raise the front using a jack, securing it with jack stands.
2. Remove the front engine covers to access the balance shaft belt, following the initial steps of Timing Belt Removal if necessary (e.g., remove air cleaner, belts, and timing belt covers).
3. Locate the balance shaft belt on the right side of the engine (driver’s side in the U.S.), running between the balance shaft sprockets and crankshaft.

Step 2: Check the Balance Shaft Belt Tension

4. Press the balance shaft belt midway between the upper balance shaft sprocket and crankshaft with moderate thumb pressure. The belt should deflect approximately 5mm (0.2 inches).
5. If using a tension gauge, measure the belt tension and compare it to the Porsche-specified value (consult the Porsche 944 Workshop Manual, typically 20–30 N for the balance shaft belt).
6. Inspect the balance belt tensioner roller (944 102 025 07) for wear or noise. Replace if necessary.

Step 3: Adjust the Balance Shaft Belt Tension

7. Adjust the belt tension based on your model year:

For Pre-85.5 Models (1983–1985.5):
Loosen the eccentric tensioner roller using a 17mm (11/16 inch) socket, turning counterclockwise to reduce tension.
If the tensioner stud (944 102 216 01) is worn or damaged, replace it and torque to 30 Nm (22 ft-lbs) using a 13mm (1/2 inch) wrench. Verify the stud length (101 mm or 106 mm for early models).
Tighten the eccentric tensioner roller clockwise until the belt deflects 5mm (0.2 inches) under thumb pressure or matches the specified tension with a gauge.

For 85.5 Onwards Models (1985.5–1988):
Loosen the spring-loaded tensioner adjustment bolt with a 19mm (3/4 inch) socket to reduce tension.
Tighten the adjustment bolt until the belt deflects 5mm (0.2 inches) or matches the specified tension with a gauge.

8. Rotate the crankshaft two full turns using a 19mm (3/4 inch) socket to ensure the belt tracks correctly and timing marks remain aligned.
9. Recheck the belt tension and readjust if necessary to maintain 5mm (0.2 inches) deflection or the specified tension value.

Step 4: Finalize and Test

10. Reinstall the front engine covers and any components removed for access, following the final steps of Timing Belt Installation.
11. Lower the vehicle from the jack stands and start the engine to check for abnormal noises or vibrations from the balance shaft belt area. Shut off immediately if issues are detected.

Post Procedure Checklist

• Verify the balance shaft belt tension is correct, with 5mm (0.2 inches) deflection or matching the Porsche-specified value.
• Confirm the tensioner stud (944 102 216 01) was replaced for Pre-85.5 models if damaged, and torqued to 30 Nm (22 ft-lbs).
• Ensure the balance belt tensioner roller (944 102 025 07) is in good condition and spins smoothly.
• Check for smooth engine operation with no unusual noises or vibrations from the balance shaft belt.

Sources

• Clark’s Garage (for maintenance intervals and tensioner stud details)
• Pelican Parts (for standard tension checking and adjusting procedure)
• Porsche 944 Workshop Manuals (for tension specifications and torque values)
• YouTube (for visual reference of balance shaft belt tension adjustment)