Piston skirt seizure on one side only without matching wear marks on the counter-side

• Severe, darkly discoloured seizure areas with a heavily worn surface on the pressure side of the piston.
• Opposite side of the piston skirt free of damage.
• Piston ring zone usually undamaged in the early stages.

This is a typical example of seizure due to lack of lubrication. It usually occurs on the pressure side and is less common on the anti-thrust side. This damage is caused when the lubricating film breaks down on only one half of the cylinder. It is caused either by a lack of lubrication within a locally confined area or by the affected side of the cylinder overheating. Lack of clearance can be excluded as the potential cause here as, despite the severity of the seizure marks, there are no wear marks on the opposing counter-side.

• Partial collapse of the cooling mechanism due to lack of coolant, air bubbles, dirt deposits or other malfunctions in the cooling circuit.
• On ribbed cylinders, dirt deposits on the outside can lead to localised overheating and, consequently, a breakdown of the oil film.
• On air-cooled engines: defective, missing or incorrectly installed air baffles.
• Failure of the oil injection jet for cooling the piston.
• Insufficient oil pressure: insufficient lubrication on the cylinder pressure side for connecting rods with oil injection jets.
• Insufficient lubrication on the cylinder pressure side (which is subjected to greater loads) as a result of oil dilution or oil grades that are not suited to the intended purpose.