Attention! If the engine has been overheated, it is possible that the cylinder head is deformed. Therefore, it must be carefully checked.
Cleaning
1. Remove the remnants of the old gasket from the cylinder head.
2. Clean the carbon from the combustion chambers, then wash the head in an appropriate solvent.
3. Remove carbon deposits from the valve, possibly even with a wire brush.
Examination
Cylinder head
1. Carefully inspect the cylinder head for cracks or other damage. If there are cracks, the head must be replaced.
2. Using a metal ruler and feeler gauge, check the flatness of the mating surface of the cylinder head. With a non-flatness of more than 0.1 mm, it is necessary to regrind the head, while its height must meet the requirements.
3. Check the condition of the valve seats. If they are burnt, worn, or defective, they must be replaced. If the wear of the valve seat is negligible, they must be lapped.
4. Check the valve guides for wear by inserting the valve stem into them and moving it sideways. The movement should be small. If movement is excessive, remove valve and measure valve stem diameter, replace valve if necessary. If the valve stem is not worn, the guide bushing is worn and needs to be replaced. Valve guides should be replaced at a Peugeot station.
5. When replacing valve guides, the valve seats must be ground and lapped.
6. On diesel engines, inspect swirl chambers for damage and splits. Small cracks are acceptable. Replacing the swirl chambers is necessary if they are severely burned and deformed or their fit in the cylinder head is loose. The swirl chamber must be replaced by a specialist.
7. Check the protrusion of the swirl chamber from the cylinder block. To check the protrusion, install the dial gauge bracket on the cylinder head mating surface, place the dial gauge tip on the cylinder head surface, set the dial indicator to 0, then move the dial gauge tip to the swirl chamber. On the indicator scale, read the amount of protrusion of the vortex chamber. Check the protrusion of the other swirl chambers in the same way.
Valves
8. Check each valve seat for localized corrosion, burns, cracks, and general wear. Check the valve stem for wear and bending. Check valve stem end wear. If there are any defects, the valve must be replaced.
9. Using a micrometer, measure the diameter of the valve stem at several points along the length of the stem. Any significant difference in the data obtained indicates wear on the valve stem and a mandatory replacement of the valve.
10. If the valves are in satisfactory condition, they should be inserted into their places and lapped. If the valve discs or seats are badly worn, they must be machined or even replaced before lapping.
11. Lapping of valves is performed as follows. Install the cylinder head with the combustion chambers up on wooden blocks.
12. Lubricate the valve seat and valve seat with lapping paste, place the valve in place and place the suction cup with holder on the valve seat (pen). By rotating the valve with the suction cup in different directions, grind the valve, and periodically it is necessary to lift the valve to redistribute the lapping paste.
13. If coarse lapping paste is used, lap until a uniform matte surface appears on the valve seat and valve. Then wipe off the paste compound used and repeat the lapping process with the fine paste. Lapping is carried out until a light gray-matte color appears.
14. Carefully remove traces of lapping paste using an appropriate solvent.
Valve elements
15. Check valve springs for signs of damage. The minimum free length is not defined by Peugeot, so the only way to test a spring is to compare it to a new spring.
16. Install the springs with one of the ends on the frame, check the deviation of the spring axis from the vertical plane and the length of the springs. If one of the springs is damaged, all the springs in the set must be replaced.
17. Replace oil seals regardless of their condition.