Camshaft (Timing) Belt and Balance Shaft Belt Tension — Checking and Adjusting

Tools

• Jack stands
• Floor jack
• Metric socket set
• Metric wrench set
• Porsche Timing Belt Tension tool (P9201)
• Thin 24 mm and/or thin 27 mm open-end wrench (depending on style of eccentric roller)

Refer to the applicable timing belt arrangement diagrams:

• 1983–1986 944 timing belt arrangement
• 1987–1991 944 timing belt arrangement
• 1992–1995 968 timing belt arrangement

Procedure

Initial Tensioning on Belt Installation (1983–1986 Cars Without Spring Tensioner)

1. Pre-tension the camshaft belt by turning the tensioning roller eccentric nut (thin 24 mm or thin 27 mm open-end wrench) counterclockwise until the belt can be twisted 90° using the thumb and forefinger. Check at the midpoint between the cam sprocket and the crankshaft sprocket. Tighten the tensioning roller locknut to 45 Nm (33 ft-lbs). Apply counter-torque to the tensioning roller eccentric nut while tightening the locknut to prevent altering the belt tension.

Note: This twist method was the original tensioning technique on 928s and 924s, and some shops continue to use it on 944s. However, it is very difficult to ensure proper tension without the factory gauging tool. It is strongly recommended to verify belt tension with Special Tool P9201.

Belt Tensioning (1987 and Newer Cars With Spring Tensioner)

1. Release the spring tensioner by loosening the locking nut and locking bolt near the spring end of the tensioner.
2. Tighten the locking bolt and locknut to 20 Nm (15 ft-lbs).

Checking and Adjusting Cam Belt Tension (All Cars)

Spring tensioners do not consistently apply the same tension and will not bring a new belt to within the new-belt tolerance (4.0 ±0.3) without manual verification. Checking tension with Special Tool P9201 is important regardless of tensioner type.

1. After the camshaft belt has been pre-tensioned, remove the flywheel lock if installed.

Note: Do not install the starter until the crankshaft bolt is installed and torqued, as the flywheel lock will need to be reinstalled.

2. Turn the engine clockwise two complete turns using the crankshaft pulley bolt (15/16" or 24 mm) and align the mark on the camshaft sprocket with the alignment tab in the window on the distributor housing (TDC). Verify that the crankshaft is also at TDC by checking the "OT" mark in the window on the bell housing.

3. Turn the crankshaft 10° counterclockwise. This is approximately 1.5 teeth on the camshaft sprocket.

4. Check the belt tension using Special Tool P9201. Pull the lock pin on the tool to release the tension roller. Align the drag needle with the gauge needle. Install the tool on the long section of the cam belt between the cam sprocket and the cam belt idler roller, with the tool's tensioning roller on the toothed side of the belt.

Note: When checking timing belt tension, the timing belt tool is installed with the gauge oriented upside down. The flat bars on the tool must slide between the timing belt and the timing belt cover — this is a snug fit but is acceptable.

5. Push the tensioning roller against the cam belt until the locking pin on the tool engages. Read the tension on the dial.

Tension specifications:

• New belt: 4.0 ±0.3
• Used belt: 2.7 ±0.3

6. Adjusting tension — eccentric roller tensioners: a. Loosen the tensioning roller locknut and turn the tensioning roller eccentric nut (thin 24 mm or 27 mm wrench) counterclockwise, then tighten the locknut. Apply counter-torque to the eccentric roller when tightening the locknut.

   b. Repeat until the cam belt tension is within the specified tolerance. c. Torque the tensioner locknut to 45 Nm (33 ft-lbs).

7. Adjusting tension — spring tensioners: a. On the front plate of the spring tensioner there are three fasteners. Loosen the lock nut on the pivot arm (top fastener) and the locking bolt (lower). This allows the spring to retension the belt. b. Optionally, use a pry bar or balance shaft pin spanner to gently nudge the tensioner in the release direction to unstick it. Once satisfied that the tensioner has released, tighten the tensioner lock nut/bolt. c. Verify tension with the factory tool, the twist method, or an aftermarket tension tool.

Note: The intended tool for operating the spring tensioner is the balance shaft sprocket pin spanner (P9200). The spanner pins fit into two holes on the front of the spring tensioner body.

Balance Shaft Belt Tensioning (All Cars)

1. Determine the required belt tension based on belt width:

   • Old-style belt (15 mm wide): 2.7 ±0.3
   • New-style belt (18 mm wide): 3.5 ±0.5

2. Loosen the locknut on the balance belt idler roller and move it away from the balance belt so it does not contact the belt during tension checking or adjustment.

3. Check the belt tension using Special Tool P9201 on the section of the balance belt between the lower and upper balance shaft sprockets.

4. Adjust and recheck the belt until the tension is within the specified limits.

Note: If a helper is available, it is possible to adjust belt tension while the tensioning gauge is installed. However, tension should be rechecked after the tensioning roller locknut is torqued.

5. When the belt is set at the proper tension, tighten the locknut to 45 Nm (33 ft-lbs). Apply counter-torque to the tensioning roller to prevent changing the belt tension.
6. Adjust the balance belt idler roller so that the clearance between the roller and the belt at the lower balance shaft sprocket is 0.5 mm (use a 0.5 mm feeler gauge or Special Tool P9207). When properly adjusted, torque the locknut to 45 Nm (33 ft-lbs).