Precautions for installing the piston into the cylinder bore

 

Precautions for installing the piston into the cylinder bore

If no repairs were made during the overhaul, the sealing surfaces of the engine block must be thoroughly cleaned.

If necessary, carefully remove any oil and coolant residues from all threaded holes.

All cleaning should be done before installing the piston in the cylinder.

Apply new oil to all piston surfaces - do not miss the piston pin and connecting rod bearing.

Note the installation direction of the piston (installation marks on the piston top and valve pocket).

Clean the cylinder bore again with a rag and apply engine oil to its surface.

Check the piston ring retaining band for damage or dents, correct them if present or replace the tool.

When installing the piston, make sure that the mounting band or the tapered assembly sleeve must lie horizontally on the cylinder head plane.

Never install the piston in the engine without the installation tool (risk of injury, risk of ring breakage).

Do not use excessive force when installing the piston. If the piston does not slide into the cylinder, always check the retaining band. Never place the opening of the retaining band in the same position as the open end of the piston ring.

If a hammer is required for installation, only use the weight of the hammer on the top of the piston. Never use a hammer to ram the piston into the cylinder. Even if the piston ring does not break during installation, it will bend and will not be able to fully perform its function later when the engine is running.

Forced installation will not only damage the piston rings, but also the piston. This happens especially on gasoline engines. The piston top lands and piston ring lands in gasoline engines are very thin and can break easily when hit. This leads to power loss and expensive repair work.

After installing the piston, avoid dust and sand from entering the cylinder. If necessary, insert a clean cloth into the hole to avoid dirt load. Especially when working in dusty environments and/or in the open air.

Figure 1: Too large a chamfer on the cylinder bore - the piston ring pops out when installed between the piston ring band and the cylinder, and the piston sticks.

Figure 2: Small chamfer on cylinder bore - piston ring slides through gap

Piston Mercedes Benz M278 V8 4.7T STD A2780302317

Piston Audi C6 BDW 2.4L V6 STD 06E107065AD (