Removal and Replacement

Valve seats





Use a cutter set with T-wrench 83 95 204, valve seat cutter 83 93 936 (60 degrees) and valve seat cutter 78 61 040 (45).

Valve seat angles, inlet and exhaust valves: 45 degrees.

Regrinding angle: 60 degrees.

Valve seat width: Inlet valve 1.0-1.5 mm.

Outlet valve 1.5-2.0 mm

Press home the guide spindle into the valve guide from the valve seat side. Cut clean the valve seats in the cylinder head with a 45 degrees cutter. It may be necessary to remove the hard surface on the exhaust valve seat with an abrasive cloth. In most cases, the valve seat width will be too great after cutting and must be reduced. Use a 60 degrees correction cutter to reduce the width.

Apply a thin layer of grinding paste on the valve seat and insert the valve into the cylinder head. The grinding paste must not come in contact with the valve stem. Rotate with the grinding tool a few times. Clean off the grinding paste thoroughly and check the contact surface with e.g. marking ink. Repeat the grinding where required and recut if necessary.

Important
Clean off all grinding paste thoroughly after machining and ensure that no paste reaches the valve guide.

Checking valve tightness
1. Clean the combustion chamber and valve seats. Use a rotating wire brush for example. Wash the cylinder head.
2. Refit the intake valves and fit new exhaust valves. Fill the intake and exhaust chambers with methanol. Do not spill.
3. Check all valves for leaks. The fluid may dampen but not run out. If the valves are tight, fit the cylinder head, see Fitting of cylinder head (in car)
4. If the valves leak, clean and recut the valve seats and grind with paste. Check the valve clearances, see Checking valve clearances.