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In an engine the cylinder head sits above the cylinders on top of the engine block. If your engine has overheated or had a cooling system failure, it could crack or distort the cylinder head.
If your cylinder head is removed we would always recommend a pressure test as a cracked head can be the cause or a symptom of overheating.
When we pressure test a cylinder head we are looking for any external or internal leaks. We do this by blanking the water outlets on the cylinder head and then pressurising the cylinder head with compressed air at 40psi. We would then confirm if the cylinder head is leaking.
The head is heated up to temperature of 40 degrees as we test it.
Due to the constant thermal expansion and contraction of the cylinder head any flaws in the casting can be exposed causing cracks in the cylinder head, a pressure test can check if these cracks are leaking.
A cylinder head can crack internally, so even if no cracks are visible on the cylinder head it is always worth pressure testing to confirm the cylinder head is ok to re-fit.
We are able to pressure test cylinder heads of most vehicles, from the smallest car to the largest commercials.