Cylinder Heads

Four stroke cylinder heads are small and commonly manufactured from cast iron. DMI Dubai’s reconditioning process involves detailed inspection to address all critical areas of the cylinder head. Before any repair is carried out, we conduct a pressure test to identify any leakages. Typical engines that we recondition are Sulzer, Wartsila, Daihatsu, MAK, MAN B&W, Yanmar and SEMT Pielstick.

Common failure characteristics observed in four stroke cylinder heads include:

• Exhaust valve pocket leakage
• Highly corroded exhaust valve pocket
• Ovality in the exhaust and inlet pocket
• Misalignment of valve guides
• Cracks near the exhaust & inlet valve pockets

The reconditioning process for cylinder heads includes:

• Chemical cleaning to de-carbonize
• Pre-inspection.
• Grinding or renewal of seat rings and valve spindles.
• Renewal of valve guides and servicing of rotor caps.
• Machining of landing and combustion faces.
• Assembly, pressure testing and final inspection

Cylinder head repairs

Due to extensive corrosion on exhaust side pockets, they may have to be machined out to the next available oversize. Additionally, ovality of exhaust valve pocket must be identified and removed. Since cylinder heads are made of cast iron, any welding, should it be required, will be done by fusion welding. Over the years we have observed that the use of fusion welding for crack repair on cylinder heads has achieved better metallurgical and machining properties than those of parent materials.