TIMING CHAIN TENSIONER FAILURES

If you suspect that your timing chain is worn then you can check the extent of the wear without having to disassemble the engine. This is done by making use of the tensioner assembly located on the rear of the pulley end of the cylinder head as shown.

Tensioner Location (9000 Only)

Remove the 12mm bolt on top of the tensioner body, taking care to recover the rubber 'O' ring, spring, and plastic insert. Then remove the tensioner body with a 27mm socket taking care not to move the tensioner leg.

Tensioner Breakdown

The chain wear can be estimated by measuring the distance between the tensioner body and the inside of the leg.

A spacing of more than 11mm suggests a seriously worn chain which will result in failure and very expensive engine repairs and you should replace your timing chain as soon as possible.

A spacing of less than 11mm suggests that the chain is not seriously worn, but does not give any indication of other critical components such as worn teeth or guides. If your engine rattles when started from cold you should have it looked at by an expert.

The tensioner is reinstalled by pushing down on the ratchet to release the leg, refitting the tensioner body into the cylinder head to a torque of 63Nm (47ftlb). Then place the plastic insert and the spring into the tensioner body and refit the 12mm centre bolt, replacing the 'O' ring if necessary. This should be torqued to 22Nm (16ftlb). The pushrod retensions the timing chain as the 12mm bolt is reinstalled.

Tensioner max length allowed