Seizure

• Areas of torn-out material
• Pronounced scoring and deformation
• Exposure as well as roughening and fissures
• Occurrence of free spread measure is visible with the naked eye in comparison to adjacent bearing shells without seizure
• Overheating phenomena, such as fusing of the bearing material and discolouration, often occur together with seizure

High temperatures in the area of high mixed friction cause localised welding between the journal and bearing. These welded areas break up again, whereby the bearing material – which is softer compared to the crankshaft – is torn off. An acute lack of lubricant is the cause here. The temperature development caused by this causes overheating damage – a common side effect of bearing seizure.

Damage due to the influence of particles or initial rubbing marks may occur at adjacent bearings due to the deposits from abrasion brought in through the lubricant circuit. Initial rubbing marks are the preliminary stages of bearing seizure.

• Oil bores not free: the reason may be the incorrect installation of the bearing shells or blockage of the oil bores – the latter is often the case when biological fuels are used
• The lubrication gap is too small, meaning that a stable lubrication film cannot be formed – cause: form and geometry deviations of the shaft or journal, or bending of the crankshaft
• The lubrication gap is too large, meaning that the hydrodynamic pressure required for the formation of the stable lubricating film is not achieved
• Oil level or oil pressure too low
• Blocked oil filter
• Defective oil pump
• Leak in the oil lines
• Overstressing of the bearings: the strain is higher than the bearing is designed for – causes are chip tuning or piston seizure, for example
• Effect of particles: particles find their way into the bearing gap, causing initial rubbing marks on the journal and bearing. In the event of embedding or scoring, edges are created, resulting in greatly increased mixed friction

Seizure is amongst the most serious types of bearing damage. The bearing is destroyed and has to be replaced. If use of the bearing is continued, other engine components may be damaged.

• Check that all of the oil bores are free and that there is no blockage
• Check the actual bearing clearance: if it is not within the tolerance range, form and geometry errors are often the cause
• Check the functioning of the oil filter and always change the oil filter and oil according to the manufacturer‘s instructions
• Check the oil level and oil pressure and readjust if necessary
• Check the oil pump is functioning
• Check the oil lines for any leaks
• Check the stress of individual bearings
• Check the entire bearing set for the embedding of particles or grooves. If present, the influence of particles may have caused the formation of the initial rubbing marks