Checking and adjusting balance shaft toothed belt tension

The toothed belt tension must be checked 5. The TDC mark on the flywheel (double-

and adjusted only when the engine is cold mass flywheel) must also line up.

(room temperature).

1. Undo and remove air cleaner assembly and engine underside protection.

2. Remove Poly-Rib belt or power pump belt, respectively.


Before undoing the lock nuts, always start by slightly loosening the hexagon head bolts of the link rod.

3. Remove toothed belt cover. Undo idler until the idler no longer places a preload on the toothed belt.

4. Rotate crankshaft clockwise until TDC mark on camshaft drive sprocket lines up with mark on toothed belt cover.

6. Check basic position of balance shaft drive sprockets. The marks on the sprockets must line up with the marks on the rear toothed belt cover.

7. Prepare Special Tool 9201 for check. Pull out lock pin of Special Tool and push measuring pin opposite the lock pin all the way out. Align non-return pointer to measuring pointer.

8. Push Special Tool onto toothed belt. Push measuring button (arrows) slowly in until engagement of the lock pin is felt and read off displayed value on dial gauge.


To avoid reading errors, the non-return pointer must always be aligned to the measuring pointer after the lock pin has engaged (turn counterclockwise).

Adjusting value:

(new and used belts) 2.7 ± 0.3 dial values If required, correct toothed belt tension.


9. The sliding blocks must rest on the belt along their entire surface. During the measuring process, the Special Tool must neither be twisted nor moved on the belt.

10. When tensioning, rotate tensioning pulley clockwise. When slackening, rotate tensioning pulley counterclockwise.

Tighten hexagon nut to 45 Nm (33 ftlb), using a second wrench to lock.

11. After the toothed belt has been adjusted, follow by adjusting the idler. Using Special Tool 9207 or a feeler gauge (0.5 mm), set idler pulley to a clearance of 0.5 mm to the toothed belt in bottom balance shaft area and preload upper toothed belt train by

0 to 1 mm at same time. Tighten idler pulley in this position. If the adjustment travel is not sufficient, turn idler pulley by 180° and repeat adjustment. Tighten hexagon head nut to 45 Nm (33 ftlb), using a second wrench to lock.

Porsche 968 Balance Pulley

1 - Idler pulley

2 - Balance shaft

3 - Tensioning pulley

12. Fit toothed belt cover. Install Poly-Rib belt or power pump belt, respectively, and adjust according to specification. Fit belt or power pump belt, respectively, and adjust according to specification. Fit engine underlay and air assembly.

Do It Yourself Car Diagnosis

Do It Yourself Car Diagnosis

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