Views: 12 Author: Site Editor Publish Time: 2019-03-27 Origin: Site
Star158 found that maintaining normal engine oil pressure is a necessary condition to ensure that the friction parts of the engine are fully and well lubricated. If the oil pressure is found to be too low, stop immediately to find the cause and eliminate the car afterwards. Otherwise, it is easy to cause the crankshaft to melt due to the low engine oil pressure, and the axle is “carrying”. If it is serious, the engine may be scrapped.
Oil pressure is always too low
The oil pressure sensor is usually installed in the main oil passage. If the oil pressure gauge and the oil pressure sensor are normal, and the oil pressure gauge indicates that the pressure is too low, the possible causes of the fault can be analyzed according to the composition of the lubrication system and the oil passage. If the oil path is divided into the front and the back by the oil pressure sensor in the direction of the oil flow, the cause of the low oil pressure can be divided into two aspects: First, the oil path before the oil pressure sensor is not smooth (such as the filter Blockage) or insufficient oil supply (such as insufficient oil); Second, the oil drain after the oil pressure sensor is too fast (such as excessive crankshaft bearing clearance). Although the lubrication system composition and oil path of different engines are different, according to the above ideas, it is not difficult to diagnose the oil pressure failure.
The oil pressure gauge is out of order or is blocked by the pressure gauge oil circuit. Loosen the nut or bolt connecting the oil pipe to the oil pressure gauge (the other end is connected to the main oil passage). Observe that the pressure of the oil is large, indicating that the pressure gauge is faulty or the oil pipe to the oil pressure gauge is blocked.
Insufficient oil capacity, deterioration of oil or water in the oil. Regularly check the oil dipstick scale of the oil sump storage, add the oil according to the regulations; check the cooperation of the piston ring and the cylinder liner, and repair it seriously.
The oil grade is wrong, the viscosity is small, and the oil is too thin. Replace with new oil that meets specifications.
The diesel engine is overloaded for a long time, making the oil temperature too high and becoming thin. Reduce diesel engine load and do not allow long-term overload work.
The oil filter is clogged, so that the oil intake is reduced and the pressure is too low. Clean the oil filter.
The oil is too dirty, and the use time is too long and deteriorates, so that the filter screen or oil passage of the oil suction pan is blocked. Replace the oil with new ones and clean the filter and oil passages.
After the oil pump wears out, the internal leakage of the oil pump is increased, the pump oil quantity is reduced, or the oil pump paper pad is damaged and the oil is leaked. It can be compensated by reducing the thickness of the oil pump end cover gasket. If the pump oil is still insufficient, repair or replace worn parts and damaged gaskets.
Check if the spring of the pressure limiting valve is too soft and the valve is too worn. If the valve wears properly, check if the springs spring force is insufficient.
The oil line from the oil suction cup to the oil pump is not tightly assembled and leaks, such as the hollow bolt of the oil suction pipe is not tightly screwed. Reinstall to eliminate air leaks.
Lubrication parts such as main bearings, connecting rod bearings, camshafts and bushings wear, the clearance increases, and the lubricating oil leaks too much. Repair and replace new parts, restore the mating relationship of the parts, and make the gap within the normal range.
The outer rotor of the rotor oil pump is reversed to reduce the amount of pump oil. Reinstall so that the chamfered end of the outer rotor outer wheel should be installed in the oil pump body.
Oil pressure suddenly drops
The sudden drop of oil pressure is generally a serious leakage of oil, such as oil passage blockage, oil passage rupture, etc., will cause a large amount of oil leakage, the oil pressure reflected in the engine work will be very low.
In addition, the oil pump is damaged, such as the gear and the pump casing of the oil pump, the serious wear between the pump shaft and the bearing, or the failure of the pump shaft breaking regulator, etc., so that the oil pump cannot establish the normal working pressure.
When this happens, the engine should be turned off immediately to avoid serious mechanical accidents. Then remove the engine oil sump and focus on the leak and the oil pump.
Rapid pressure drop after normal operation at startup
The pressure is normal when the engine is started, and the oil pressure drops rapidly after running for a while. Diagnosing such faults can be done by analyzing changes in the engines lubrication system to determine the likely cause of the fault.
When the engine is just started, most of the oil flows back to the oil sump before starting, so the oil content in the oil sump is relatively sufficient. After running for a period of time, since some of the oil is pumped into the oil passage for circulation, the amount of oil in the oil sump is reduced.
Note: If the coolant or fuel enters the oil pan to dilute the oil, resulting in a decrease in viscosity, the cause of the water leakage or oil leakage should be ascertained, and the new oil should be replaced after the fault is removed.
Oil pressure is high and low
When the engine is running at idle speed, the oil pressure is normal, and the oil pressure fluctuates (the oil pressure gauge pointer swings back or forth between 0 and 0.6 MPa). The main reasons are as follows:
The oil pump is faulty (such as excessive gear wear or loose screws), and the oil pump draws air.
The adjusting valve or the return valve spring is stuck by foreign matter, or the spring is bent and rubbed against the seat hole, so that the spring movement is blocked, and the opening and closing of the ball valve is difficult.
There is a shortage of oil in the oil pan, the oil level is at the limit position of the suction port of the filter, or there is impurity in the oil pipe but not completely blocked, so that the oil pump sometimes does not absorb oil, causing the oil pressure to fluctuate.
The pressure limiting valve is improperly assembled or glued, which makes the oil flow resistance unstable, or the oil pressure gauge is damaged, and can also cause the oil pressure to fluctuate.