Camshaft (Timing) Belt Tension – Checking and Adjusting – 2.5L NA

Overview

This procedure outlines how to check and adjust the tension of the camshaft (timing) belt on all Porsche 944 variants with a 8-valve engine. Proper tension ensures the engine runs smoothly and prevents belt slippage or damage, which is critical for maintaining engine timing and performance. This guide covers the 1983–1985.5 (Pre-85.5) and 1986–1988 (85.5 Onwards) variants, focusing solely on the camshaft belt, excluding balance shaft belt procedures.

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Tools Required

• Jack stands
• Floor jack
• Metric socket set
• Metric wrench set
• Porsche Timing Belt Tension Tool (P9201)
• Thin 24 mm (15/16 inch) or 27 mm (1-1/16 inch) open-end wrench (depending on eccentric roller style)
• 15/16 inch (24 mm) socket or wrench (for crankshaft pulley bolt)

Parts Required

• Camshaft (timing) belt, 944 105 157 02 (if replacing during installation)

Required Additional Procedures

Steps in these procedures are required to complete this process:

• Timing Belt Removal
• Locating and Setting Engine to Top Dead Center (TDC)

Step-by-Step Procedure

Step 1: Prepare the Vehicle

1. Safely raise the vehicle using a floor jack and secure it on jack stands.
2. Follow this link to ensure this step – Timing Belt Removal – of the process is followed accurately to access the camshaft belt.
3. Follow this link to ensure this step – Locating and Setting Engine to Top Dead Center (TDC) – is completed to align the engine properly.

Step 2: Pre-Tension the Camshaft Belt (Pre-85.5)

4. For Pre-85.5 models:

   Use a thin 24 mm (15/16 inch) or 27 mm (1-1/16 inch) open-end wrench to turn the tensioning roller eccentric nut counter-clockwise.

   Adjust until the belt can be twisted 90° using thumb and forefinger at the midpoint between the camshaft sprocket and crankshaft sprocket.

   Tighten the tensioning roller locknut to 45 Nm (33 ft-lbs), applying counter-torque to the eccentric nut to maintain tension.

Step 3: Release and Set Spring Tensioner (85.5 Onwards)

5. For 85.5 Onwards models:

   Loosen the locking nut and locking bolt near the spring end of the tensioner to release spring tension.

   Tighten the locking bolt and locknut to 20 Nm (15 ft-lbs).

Step 4: Align Engine for Tension Check

6. Remove the flywheel lock if installed, ensuring the crankshaft bolt is torqued before proceeding.
7. Using a 15/16 inch (24 mm) socket or wrench, turn the crankshaft clockwise two complete revolutions.
8. Align the camshaft sprocket mark with the alignment tab in the distributor housing window (TDC).
9. Verify the crankshaft is at TDC by checking the “OT” mark in the bell housing window.

10. Turn the crankshaft 10° counter-clockwise (approximately 1.5 teeth on the camshaft sprocket).

Step 5: Check Camshaft Belt Tension

11. Install the Porsche Timing Belt Tension Tool (P9201) on the long section of the camshaft belt between the camshaft sprocket and the idler roller, ensuring the tool’s tensioning roller is on the toothed side of the belt.
12. Pull the lock pin on the tool to release the tension roller.
13. Align the drag needle with the gauge needle on the tool.
14. Push the tensioning roller against the belt until the locking pin engages.

15. Read the tension on the dial. Compare to specifications:

New belt: 4.0 ± 0.3

Used belt: 2.7 ± 0.3

Step 6: Adjust Camshaft Belt Tension

16. For Pre-85.5 models:

    Loosen the tensioning roller locknut.

    Turn the eccentric nut counter-clockwise with a thin 24 mm (15/16 inch) or 27 mm (1-1/16 inch) wrench to adjust tension.

    Tighten the locknut to 45 Nm (33 ft-lbs), applying counter-torque to the eccentric nut.

17. For 85.5 Onwards models:

    Loosen the locknut on the pivot arm (top fastener) and the locking bolt (lower fastener) on the spring tensioner.

    Gently nudge the tensioner to release the spring, if needed, using a pry bar.

    Tighten the locknut and locking bolt to 20 Nm (15 ft-lbs).

18. Repeat Steps 4 and 5 until the belt tension is within the specified tolerance.

Post Procedure Checklist

• Verify the camshaft and crankshaft are aligned at TDC.
• Ensure the camshaft belt tension meets specifications (4.0 ± 0.3 for new, 2.7 ± 0.3 for used).
• Check that all locknuts and bolts are torqued to the correct values (45 Nm for eccentric roller locknut, 20 Nm for spring tensioner fasteners).
• Inspect the camshaft sprocket, crankshaft gear, and idler roller for wear or damage.
• Confirm no tools or debris are left in the engine bay.

Sources

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