How many microns of cylinder head deformation is normal?
2 Answers
No more than 0.50MM. If the cylinder head has already deformed or the accumulated grinding wear exceeds 0.50MM, it is recommended to replace the cylinder head with a new one. 1. Cylinder head: The cylinder head is installed on top of the cylinder block, sealing the cylinder from the upper part and forming the combustion chamber. It is frequently in contact with high-temperature and high-pressure gas, thus bearing significant thermal and mechanical loads. The cylinder head of a water-cooled engine has a cooling water jacket inside, and the cooling water holes on the lower end face of the cylinder head are connected to the cooling water holes of the cylinder block. Circulating water is used to cool high-temperature parts such as the combustion chamber. 2. Repair method: Since there is no concave combustion chamber on the engine cover, there is no need to consider changes in combustion volume (the change in combustion chamber volume should generally not exceed 4% of the original volume). The cylinder head surface is machined using a planing method. Instead of the rubber sealing ring on the cylinder gasket, the cylinder gasket is installed, and the cylinder head bolts are tightened using a method of cold tightening followed by hot tightening.
Hey, cylinder head deformation is a common issue in car repairs. The normal tolerance should ideally not exceed 15 'si' (approximately 0.15mm). I've seen many engines where long-term high-temperature operation or over-tightened installation bolts caused deformation exceeding 10 'si' - that's when you need to be cautious. Generally, under 5 'si' is excellent, around 10 'si' is still operational, but exceeding 15 'si' can easily lead to sealing issues, causing oil or coolant leaks, and even cylinder pressure problems. During measurement, we typically use a straightedge with feeler gauges to check flatness uniformity across multiple points. If deformation exceeds standards, don't rush to replace the cylinder head - grinding treatment can often restore it. Regular maintenance of the cooling system and avoiding overheating are recommended to prevent cumulative damage.
