How to Adjust Weichai Engine Oil Pressure?
3 Answers
First, remove the oil pan. There is a long screw head nearby called the pressure relief valve. Use a steel plate to turn the inner screw - loosening it reduces pressure, while tightening it increases pressure. This is how you adjust the oil pressure for Weichai engines. The specific location varies depending on the engine type, but it's mostly found at the front or side of the main oil passage. Reasons for low oil pressure in Weichai engines are as follows: 1. Insufficient engine oil; 2. Damaged fuel pump diaphragm allowing gasoline to leak into the oil pan and dilute the oil; 3. Damaged cylinder gasket or cracked cylinder block allowing coolant to leak into the oil pan, causing oil emulsification; 4. Clogged oil collector screen or leaks in pipes and oil passages, or other parts like rocker arm shaft end cover falling off causing oil leakage; 5. Worn oil pump gear end face or improper adjustment.
When encountering abnormal oil pressure in a Weichai engine, my experience is that you should not directly adjust the pressure valve. If the oil pressure is low, first check if the filter element needs replacement—many beginners tend to overlook this. Next, check the dipstick; if the oil level is low, the pressure will definitely not rise. Last time, I encountered a vehicle with oil viscosity that was too low, and switching to the correct 15W-40 grade immediately fixed the issue. If none of these are the problem, it’s likely due to wear in the oil pump or excessive bearing clearance, which requires engine disassembly and professional handling. Remember, never casually adjust the pressure relief valve screw—incorrect adjustment could ruin the entire lubrication system.
Adjusting the oil pressure on Weichai engines requires careful attention. I always start by connecting a mechanical pressure gauge to verify the actual readings, as dashboard indicators on many older vehicles are unreliable. If the pressure is indeed low, follow a three-step troubleshooting process: First, check if the oil pan strainer is clogged—last month I cleaned one completely packed with sludge. Second, use a borescope to inspect the wear on the crankshaft bearings. Finally, examine the main oil gallery pressure relief valve for sticking. Adjusting the relief valve requires specialized tools; you must test-drive and measure the pressure after every quarter turn. Over-adjusting can cause oil line fittings to burst, which is extremely hazardous.
