Adjusting valve clearances (Opel Kadett D)

OHV engine

As part of maintenance, it is necessary to check the valve clearances every 15,000 km and adjust them if necessary. The valve clearance must be checked on a warm engine after repairing the cylinder head.

Valve adjustment only has the desired result if the valves seal perfectly, do not have unacceptable play in the guides and the ends of the rods are not broken.

If the clearance is too small, the valve timing changes, compression deteriorates, engine power decreases, and the engine runs unstably. In extreme cases, the valves may become deformed or the valves or valve seats may burn.

With a large gap, strong mechanical knocks occur, the valve timing changes, due to the lean working mixture the engine develops less power, the engine operation is unstable.

Remove the air filter, see paragraph 4.44.

Remove the cylinder head cover.



Check the valve clearance at operating temperature (approximately 80°C for coolant and 60°C for oil) and with the engine running using the appropriate feeler gauge:

• Exhaust valves 0.25 mm.
• Inlet valves 0.15 mm.

The feeler gauge should move with difficulty between the rocker arm and the end of the valve stem.





From the front of the engine, the valves are arranged in the following order: 1st cylinder - exhaust, intake, 2nd cylinder - intake, exhaust, 3rd cylinder - exhaust, intake, 4th cylinder - intake, exhaust.

If the clearance is incorrect, it can be adjusted by turning the rocker arm nut.

Note: Oil splashes from the rocker arm can be removed with a piece of cardboard (approximately 40x320 mm), which is installed between the sealing surface of the cylinder head cover and the push rods.

Screw on the timing cover with a new gasket.

Install the air filter with the heating hose, see paragraph 4.44.

Engine ONS

Thanks to the installation of hydraulic compensators, there is no need to adjust the valve clearance.

Caution: Hydraulic valve clearance compensators may cause valve train noise when the oil level is high. In this case, first check the engine oil level and adjust if necessary.

Valve stem clearance:

• Intake valves: 0.015 to 0.047 mm
• Exhaust valves: 0.030 to 0.062 mm

Permissible valve stem runout:

• Inlet valves: 0.04 mm
• Exhaust valves: 0.05 mm