Due to wear of the joints, the chain stretches over time. In addition to the chain, the sprockets of its drive also wear out. Together, this leads to a decrease in chain tension and, as a consequence, to a shift in the valve timing.
The chain tension is adjusted by loosening the cap nut of the plunger tensioner installed under the outlet pipe of the cooling system.
To visually check the operation of the tensioner, adjust the chain tension with the cylinder head cover removed (see "Cylinder Head Cover Gasket - Replacement"). If there is no doubt about the serviceability of the tensioner, there is no need to remove the cover.
Sequence of execution
1. Prepare the car for work (see "Preparing a car for maintenance and repair").
2. With a socket wrench by 13 mm we loosen the tensioner cap nut ("discharge" the tensioner), while its shoe should move, tensioning the chain.
3. If the shoe does not move, the cause is the plunger jamming in the collet lock. To eliminate the malfunction, use a hammer to lightly hit the nut several times to release the tensioner plunger.
4. Key by 38 mm we turn the crankshaft clockwise by 1.5-2 turns and stop it at the moment of greatest resistance to rotation, holding the shaft from turning in the opposite direction.
5. Tighten the tensioner cap nut and install the cylinder head cover.
6. Start the engine and check the operation of the chain by ear.