- a special template or a wide metalworking ruler;
- set of flat feeler gauges.
Sequence of execution
1. Remove the cylinder head (see "Cylinder head - removal and installation").
2. We clean the cylinder head from dirt and carbon deposits, wash it from oil deposits, and remove carbon deposits from the walls of the combustion chambers with a metal brush.
3. Carefully inspect the cylinder head. There should be no cracks. There should be no scoring or metal drag on the working surfaces of the camshaft supports and the walls of the tappet mounting holes. The valve guides and seats should fit tightly in the head body, without any signs of displacement during the operation of the timing system. The valves and their seats should not have cracks or signs of burnout.
4. Check the flatness of the head. The work is carried out in two stages. For this, a special template is required, but if you do not have one, then you can check the lower bearing plane of the head with sufficient accuracy using a wide metalworking ruler. Apply the ruler diagonally, with the edge to the plane of the head. Make sure that there is no gap between the edge of the ruler and the plane of the head. The gap can be observed both in the middle part of the plane and along its edges. We measure the gap along both diagonals using a set of flat feeler gauges.
The maximum allowable gap is 0.1 mm.
Recommendation: If the gap is greater than the permissible value, the head must be milled at the mating surface or replaced.
5. Check the tightness of the cylinder head. To do this, plug the window on the end surface of the head that supplies coolant to the thermostat (you can install the thermostat pipe by placing a gasket cut from sheet rubber underneath it). We turn the head over and fill its internal cavities for coolant with kerosene.
6. Make sure there is no kerosene leak from the cylinder head.
Recommendation: If a leak is detected, as well as if there are cavities on the mating surface, you can try to repair the cylinder head using cold welding or replace it.