If an engine has overheated or blown a head gasket the cylinder head can become distorted, if this is the case we are able to resurface or skim the cylinder head to bring it back into tolerance and create the perfect sealing finish.
In modern engines the cylinder head finish should be within 10 microns, this is because most modern engines use a steel laminate head gasket, called a M.L.S gasket i.e. “multi layered shim”. These gaskets provide a stronger body plate and helps conduction between block and cylinder head, this helps stabilise thermal expansion and contraction, thus reducing stress. Since the M.L.S gasket material is unforgiving any flaws in the surface finish of the cylinder head can lead to premature gasket failure. In our well-equipped workshop, we are able to obtain the correct surface finish using our precision equipment and years of experience.
As well as a head becoming distorted, it can also become corroded over time, which may necessitate a skim. If a gasket has blown, it may leave a mark on the surface of the head, which may require skimming.
We are able to resurface most petrol cylinder heads with the valves in place, however on the majority of diesel cylinder heads the valve protrude above the surface of the head and would need to be removed prior to resurfacing the head. Once the head has been resurfaced, we may need to resurface the valves and valve seats to set them back to the correct depth/height.
When resurfacing the cylinder head we always try to remove the minimum amount of materials as possible to remove any distortion without drastically altering compressions.