The bearing oil inlet is blocked, which reduces the amount of oil feed, the phenomenon is that the bearing return oil temperature is increasing. The bearing has sundries inside or the bearing proper is in failure. Oil quality deterioration:  the phenomenon is that all bearing temperature rise, but the oil pressure is normal, the reasons of the phenomenon is the that the oil in the water, etc.The uneven distribution of the oil input of each bearing will cause some bearing oil temperature to be high and some  bearing oil temperature to be low. Oil cooler is not working properly, the reasons roughly are:
1. The water side of the oil cooler is blocked by mud, sand and other miscellaneous dirty, so the cooling water is not enough, at this moment, the inlet and outlet temperature difference of cooling water will increase significantly.
2. The oil side of the oil cooler is attached by the sludge and oil dirties, lowering the heat transfer efficiency, at this moment, the inlet and outlet temperature difference of cooling water will decrease significantly, the difference of cooler water outlet temperature and oil cooler outlet temperature will increase significantly.
3. The air leaks to  water side of oil cooler or water source is in failure , so water loss happens, at this moment, the difference of inlet and outlet oil is decreasing significantly or is almost not available, the cooling water temperature rises.（js）