- a special template or a wide locksmith's ruler;
- flat feeler set.
Check sequence
1. Remove the head from the car (see "Cylinder head - removal and installation").
2. We clean the head and bearing housing from dirt and carbon deposits, wash it from oil deposits, remove carbon deposits from the walls of the combustion chambers with a metal brush.
3. Carefully inspect the cylinder head and bearing housing. They should not have cracks. On the working surfaces of the camshaft bearings, the bearing housing and the walls of the seats of the hydraulic compensators, there should be no scoring and traces of metal enveloping.
The guides and valve seats must fit snugly in the body of the head, with no traces of their displacement during timing operation. Valves and their seats must not have cracks or burn marks. We check the backlash of the valves in the guides, the maximum allowable clearance is 0.30 mm.
4. Check the flatness of the cylinder head. We carry out the work in two stages.
This requires a special template, but if it is not there, then you can check the lower mating plane of the cylinder head with a sufficient degree of accuracy using a wide locksmith's ruler.
With an edge, we apply a ruler diagonally to the plane of the head.
We 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 with a set of flat probes.
The maximum allowable gap is 0.1 mm.
If the clearance is greater than the allowable, the cylinder head must be milled (mating plane) or replacement.
Warning. The head should only be replaced complete with bearing housing.