Gas distribution mechanism — bulkhead (Peugeot Eurovans 806)

We do not recommend that you overhaul the gas distribution mechanism yourself. In the event that wear or damage to parts is revealed during the inspection of the mechanism, the engine should be delivered to a workshop that will perform a bulkhead.

Valves

Small damage to the surfaces of the valve heads can be repaired by lapping the valves in the cylinder head seats.

1. Measure the valves and compare them to specifications. Valves, the wear of which exceeds the established tolerances, replace with new ones. Pay special attention to the condition of the chamfers of the valve heads and the absence of burning of the chamfers. The thickness of the valve heads must be at least 0.50 mm. We recommend replacing those valves whose head thickness is close to the minimum allowable thickness at the time of inspection. When determining the thickness of the valve head, the thickness of the chamfer of the head is measured.

If the ends of the valve stems are worn, they can be machined on a grinding machine. In this case, it should be taken into account that during the grinding process, no more than 0.5 mm of the rod material can be removed.

Valve heads can be machined on a special valve grinding machine, provided that the remaining thickness of the valve stems after grinding is not less than 0.5 mm.

2. Check the condition of the valve stems and measure the inside diameter of the valve guides. To do this, you will need a micrometer to measure the inner diameter and a micrometer to measure the outer diameter.

Valve seats

3. Check the condition of the valve seats for wear or pitting. Defects in the form of slight wear can be eliminated by milling 45°chamfers. If the valve seats are sufficiently worn, the valve seats must be remilled or the seat rings replaced. To replace the rings, it is necessary to drill holes for the seats, which is recommended to be entrusted to an engine repair shop.

Valve springs

To properly check the valve springs, you need an appropriate tester, which determines the length of the spring (deformation) under load. And in this case, it is best to contact the workshop.

Valve guides

If it turns out that the inside of the valve bushings is worn, then it is best to contact an engine repair shop to perform the appropriate measurements and, if necessary, replace the bushings. When replacing the guide bushing, the valve seats will need to be milled. And this means that almost the entire gas distribution mechanism needs to be sorted out.

Cylinder head

4. Clear mating surfaces of a head of the block of cylinders and the block of cylinders and be convinced that the head has no misalignment. To do this, install a measuring ruler on the cylinder head and use a template to measure the gap between the ruler and the surface of the cylinder head in the longitudinal, transverse and diagonal directions. If a template with a thickness of more than 0.05 mm can be inserted into the gap, then grinding of the head is necessary. If at least in one place the gap is greater than the specified size, then the cylinder head should be replaced with a new one. The cylinder head can be reworked if no more than 0.02 mm of metal needs to be removed to correct it. We also recommend entrusting this work to a workshop (see illustration).

Camshaft

As already mentioned, the camshaft (or shafts) are not universal. This must be taken into account when replacing the camshaft, and when ordering a new shaft, indicate the type of engine, the year of manufacture of the engine, as well as the power in hp. or in kW.

8. Check the condition of the shaft journals and check for damage. If the necks are damaged, then we recommend replacing the camshaft and cylinder head, rather than repairing and overhauling them.

9. Install the camshaft to measure the end play in the cylinder head and secure it with a thrust plate. Place the cylinder head on a level surface (see illustration).



10. Attach an arrow-type indicator to the end of the shaft and move the camshaft back and forth in the axial direction. If the play exceeds 0.16 mm, the thrust plate is worn and must be replaced. In the worst case, wear of the camshaft flange, which is fixed between the cylinder head, is possible (with bearing housing) and accessory housing.