Camshaft (Timing) Belt Tension – Checking and Adjusting

Overview

This procedure explains how to check and adjust the tension of the camshaft (timing) belt on your Porsche 944 S2 with its 3.0L engine. Proper tension is essential to keep the belt running smoothly, preventing engine damage from slipping or snapping. It’s a key maintenance step to ensure your S2’s performance stays reliable.

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Tools Required

• Jack stands
• Floor jack
• Metric socket set
• Metric wrench set
• Porsche Timing Belt Tension Tool (P9201)
• 24mm (15/16 inch) wrench (for crankshaft pulley bolt)
• Balance shaft sprocket pin spanner (P9200) or pry bar

Parts Required

• Timing belt, 944 105 157 04 (specific to S2 3.0L)

Required Additional Procedures

Steps in this procedure are required to complete this process:

• Camshaft (Timing) Belt Removal
• Camshaft (Timing) Belt Installation

Important Information Before Proceeding

This short explanation ensures that you understand how the timing belt functions when releasing the auto-tensioner:

When releasing tensioner it is important understand which length or span (upper or lower) of the belt the tensioner will impact the most. The timing will be difficult to get right without this understanding.

When placing the belt into position on the camshaft sprocket, the length of belt before the timing mark, that routes beneath the camshaft sprocket (gear)and over the water pump pulley, is the length of belt that will be most impacted by the tensioner.

In other words, BEFORE releasing the tensioner, the length of belt you need to work on getting as tight as possible without impacting the timing is the upper span of the belt.

This span is the direct connection between the cam and the crank.

When this span of the belt is nice and tight, it holds the camshaft sprocket and crankshaft gear in timing.

WITHOUT THE FLYWHEEL LOCK – When the tensioner is released, it is going to pull the crankshaft ever so slightly clockwise which will, in turn, pull the camshaft sprocket slightly clockwise as well. A split second after this rotation occurs the bottom span of the timing belt will be tensioned by the tensioner and pull back on the camshaft sprocket. This movement of the crankshaft gear versus the camshaft gear (which is now “held back” by the tensioner) is where the correct tension will come from.

WITHOUT THE FLYWHEEL LOCK – The upper span must be as tight as you can get it – in other words, the teeth of the belt must be sitting right inside the receiving grooves of the camshaft sprocket and crankshaft gear.

When releasing, prevent jumping by putting downward pressure on the belt at the 9/10 o’clock position on the camshaft gear. 

WITH THE FLYWHEEL LOCK – the opposite occurs to the camshaft sprocket because the crankshaft doesn’t move at all. In this scenario, the camshaft is rotated anticlockwise (counter-clockwise), which creates the tension required.

NB – In both of these, you will understand that the starting position of the timing marks require a slight adjustment in order to be correctly lined up after the tensioner has been released.

Step-by-Step Procedure

Step 1: Prepare the Engine

1. If this is being done to check tension only, use the needed steps in this procedure – Camshaft (Timing) Belt Removal – to gain access to the timing belt.
2. If you have previously removed your timing belt, follow this link to ensure the needed steps – Camshaft (Timing) Belt Installation – of this process are followed accurately.
3. Remove the flywheel lock if it’s installed (do not reinstall the starter yet).

Step 2: Pre-Tension the Camshaft Belt

4. Locate the spring tensioner on the front of the engine (specific to the S2’s 1989-1991 design).
5. Loosen the locking nut and locking bolt near the spring end of the tensioner using a wrench.
6. Gently nudge the tensioner with a pry bar or balance shaft sprocket pin spanner (P9200) to release the spring and apply tension to the belt.
7. Tighten the locking bolt and locking nut to 20 Nm (15 ft-lbs) using a torque wrench.

Step 3: Check and Adjust Camshaft Belt Tension Using Porsche Tool

8. Turn the engine clockwise two full turns using the crankshaft pulley bolt with a 24mm (15/16 inch) wrench.
9. Align the camshaft sprocket mark with the tab in the distributor housing window (Top Dead Center, TDC). Check the crankshaft “OT” mark in the bell housing window to confirm TDC.

10. Rotate the crankshaft 10° counterclockwise (about 1.5 teeth on the cam sprocket).
11. Set up the Porsche Timing Belt Tension Tool (P9201): pull the lock pin to release the roller, align the drag needle with the gauge needle, and install it between the cam sprocket and idler roller, with the roller on the belt’s toothed side.

12. Push the tool’s tensioning roller against the belt until the lock pin engages, then read the tension on the dial.
13. Compare the reading to the specs: 4.0 ± 0.3 for a new belt, 2.7 ± 0.3 for a used belt.
14. If adjustment is needed, loosen the tensioner’s top lock nut and lower locking bolt, nudge the tensioner to adjust, then tighten both to 20 Nm (15 ft-lbs). Repeat steps 11-13 until the tension is within spec.

Step 4: Check and Adjust Camshaft Belt Tension Without The Porsche Tool (At Your Own Risk)

15. At the midpoint between the cam sprocket and the crankshaft sprocket, grab the timing belt between your thumb and forefinger, and twist it using slightly higher than average normal finger pressure.
16. If the belt can be twisted 90° using the thumb and forefinger, you are in the correct range.
17. A second point of feedback is turning the water pump pulley by hand: If it turns too easily, the timing belt is too loose. If it won’t turn at all or you can just get it to budge – it’s too tight. But if it turns while still requiring a decent grip and effort, then it is another indication your timing is in the correct range.

Post Procedure Checklist

• Double-check camshaft belt tension is within 4.0 ± 0.3 (new) or 2.7 ± 0.3 (used).
• Ensure the tensioner lock nut and bolt are torqued to 20 Nm (15 ft-lbs).
• Rotate the engine by hand two full turns and recheck TDC alignment.
• Inspect for any unusual noises or belt misalignment when turning the engine.

Sources

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