Piston damage and causes

Information on diagnostics

Piston seizure or piston broken? What was the cause of the damage? We will help you to correctly diagnose damage in day-to-day repair shop activities and prevent expensive consequential damage.

Piston crown damage

Seizure due to overheating (mainly piston crown)

Overheating due to combustion defaults
Bent/blocked oil injection jet
Installation of incorrect pistons
Malfunctions in the cooling system
Clearance restriction in the upper sliding surface area

Impact marks

Piston protrusion too great
Excessive remachining of the cylinder head sealing surface
Incorrect valve recess
Incorrect cylinder head gasket
Carbon deposits on the piston crown
Insufficient valve clearance
Incorrect valve timing caused by incorrect adjustment or a slipped toothed belt

Fused/melted off material

Faulty injection nozzles
Incorrect quantity of injected fuel
Incorrect injection point
Insufficient compression
Ignition delay
Oscillating injection lines

Cracks in the crown and crown bowl

Faulty or incorrect injection nozzle
Incorrect injection point
Incorrect quantity of injected fuel
Insufficient compression
Lack of piston cooling
Installation of pistons with incorrect bowl shape
Improvement in performance (e.g. chip tuning)

Piston ring damage

Material washout in the ring area

Incorrectly installed pistons
Fuel flooding
Severe axial wear of the ring groove and piston rings
Ring flutter

Radial wear due to fuel flooding

Fault during mixture formation
Combustion defaults
Insufficient compression pressure
Incorrect piston protrusion dimension

Axial wear due to ingress of dirt

Abrasive dirt particles due to inadequate filtration
Dirt particles that are not completely removed during
reconditioning of the engine (chips, blasting agent)
Abraded particles caused when the engine is being run in

Piston skirt damage

Asymmetrical piston wear pattern

Bent/twisted connecting rod
Connecting rod eyes bored at an angle
Cylinder bore not straight
Individual cylinders not installed straight
Excessive connecting rod bearing clearance

45° seizure

Excessively narrow fit of the piston pin
Seizure in connecting rod eye (inadequate lubrication at initial start-up)
Incorrectly installed shrink-fit connecting rod

Dry running/Fuel damage

Over-rich engine running
Combustion defaults (misfiring)
Insufficient compression
Defective cold-start device
Oil dilution with fuel

Cylinder liner damage

Cavitation

Poor/inaccurate seating of the cylinder liner
Use of incorrect O-ring seals
Use of unsuitable coolant agent
Insufficient prepressure in the cooling system
Operating temperature too low/too high
Restricted coolant flow

Bright spots in the upper cylinder area

Carbon deposits on the piston top land due to:

Excessive ingress of oil into the combustion chamber due to defective components
Increased emissions of blow-by gases with oil entering the intake air system
Insufficient separation of oil vapour from the blow-by gases
Frequent idling or short-distance drives