What are the faults of engine sliding KOYO bearings?

There are many kinds of sliding KOYO bearings on an engine, whether bushing or bearing bush belong to sliding KOYO bearings. In order to ensure the operation accuracy of the 

engine, the clearance requirements of these sliding KOYO bearings are also very high. The failure of engine sliding KOYO bearings can be attributed to: lubrication criticality and 

any interference that causes the destruction of operating clearance and any material that destroys the oil film. For example, inaccurate installation and adjustment, parts have 

knock damage and poor cleanliness, incorrect use methods, harmful chemical reactions, etc., will lead to the damage of sliding KOYO bearings. According to the American 

Cummins engine fault analysis book statistics, caused by sliding KOYO bearing damage of the main reasons are four aspects. The percentage of failures in these four aspects is 

as follows:

1. Damage caused by cleaning is 45%;

2. Damage caused by lubrication is 25%;

3, due to the use of damage, installation of 15%;

4. Damage caused by surface reaction and other aspects is 15%.

From this statistical proportion, we can see that the damage caused by cleanliness to KOYO bearings is the main reason. The task of preventing damage caused by poor 

cleanliness is multifaceted: ensuring the cleanliness of parts during engine assembly is only one aspect, while the engine is in use is another. Operators and maintenance 

personnel must be in accordance with the provisions of the correct use of timely maintenance inspection, especially in the long-term dust and chemical materials in the 

environment of the engine, must take measures to prevent dust and chemical gas erosion, to ensure the service life of the engine. The engine spindle tile, connecting rod tile 

surface alloy layer is the most soft, bear the largest load, but also the most easy to damage, so the following is to the main shaft tile and connecting rod tile surface damage 

phenomenon, analysis of the cause, in order to avoid repeated failure after repair.

I. Faults caused by cleanliness problems:

1. Abrasion caused by small particles of foreign matter on bearing bush:

When the oil filter and the oil drain plug of the engine oil pan, the first tens of milliliters of oil out of the oil, there are more alloy powder that can be seen directly by the naked 

eye, the bearing bush has been worn. This is due to the small particles of impurities into the bearing alloy layer caused by the movement of the surface, while the bearing bush 

did not cause serious damage, but if this kind of phenomenon continues, not only bearing early damage, shaft can also severely damage, so must be based on the cause of 

failure in a timely manner to eliminate, avoid to cause the damage of the parts. After troubleshooting, the service life of the engine bearing bush cannot be calculated according 

to the normal wear time, because the abnormal wear amount of a small particle is equivalent to 2500 hours of normal engine wear.

The reasons for the entry of small particles: first, the filtration effect of the air filter is poor or the intake system is not sealed well. It is necessary to check the pipes and 

connections of each part of the intake system, whether there is rupture and loosening, and check whether the filter element is loose and the paper core is broken. Whether 

maintenance or maintenance of the entire intake system inspection is very important, must ensure reliability. Second, after lubricating oil is polluted, it is added to the engine 

or oil and filter element for too long. All the filter elements of the machine are blocked, so that the oil on the lubrication surface directly enters the filter element without 

filtering. 

Third, the fuel supply is too large to finish burning, nozzle leakage, resulting in fuel infiltration into the crankcase, while some impurities with fuel into the crankcase 

and oil mixed together to reduce the lubrication effect. Therefore, in the use of the engine, we should pay attention to the smoke exhaust and operation of the engine. If there 

is any abnormality, we should find out the cause in time for repair or replacement. Fourth, when the engine is assembled, the cleanliness of internal parts is poor. In the repair 

and maintenance of the engine, we must pay attention to the cleanliness of the parts, and pay attention to the prevention of re-pollution during installation to ensure the cleanliness of the interior after installation.

Either way, the engine oil and filter element must be replaced after troubleshooting. After repair of engine starting idle running two hours stop for inspection, there are no alloy 

powder in the oil, may use in half load, but in the first few days of use must be observed, after 60 ~ 120 hours operation decision after confirm the abnormal wear and tear is 

completely ruled out, oil change again, the engine can be put into normal use. If abnormal wear continues to develop, it must be discontinued for disassembly inspection and 

repair.

2. Damage caused by larger particles and inferior lubricating oil to bearing bush:

In the oil filter and engine oil pan found larger particles of alloy block or thin section, the shaft and bearing bush has been seriously damaged, must be immediately shut down 

for inspection and repair, if continue to use will cause more parts damage.

Larger particles into the reason: when installation parts not clean, such as, the connecting rod bushing hole processing scrap metal remaining in the connecting rod oil passage, 

parts and oil passage with cutting or silt, not completely clean before installation, or related to sports surface machined part machining burrs flanging is not clear, installing a 

bearing with large particles of foreign matter or shaft surface is damaged. The damage caused by these phenomena to bearing bush is very serious. So in the maintenance and 

installation should be carefully cleaned cleaning and inspection.

Inferior oil lubrication effect and thermal effect can not meet the requirements, make the bearing and shaft wear, sports surface damaged bearing alloy melting and high 

temperature, at the same time, inferior oil impurities more oil filter was quickly blocked, lubricating oil containing impurities without direct filtration, the surface of the 

movement to further accelerate the damage of the shaft and bush. So when buying and replacing lubricating oil, we must strictly control the quality of lubricating oil according 

to the provisions, and choose lubricating oil according to the provisions.

3.do not move the foreign body damage to the shaft and bearing bush:

There is a large foreign body clamped in the bearing and tile mounting hole between the inner wall, the moving surface of the bearing will produce convex point, when the shaft 

is running, abnormal wear will start from the convex point, and to the periphery expansion, causing early damage to the shaft and bearing; If there is a large foreign body 

between the moving surface of the bearing and the shaft, it will be embedded in the alloy layer of the bearing after installation, and the bearing will be damaged during operation 

while the shaft is damaged; Shaft and tile and installation hole and other related parts such as bump bump point will cause damage or damage to shaft and tile.