Why Does an Engine Leak Air?
2 Answers
The reasons for engine cylinder air leakage are as follows: 1. The parking solenoid fuel inlet valve malfunctions. 2. The diesel level in the fuel tank is extremely low, or the fuel tank breather valve is not opened. In this case, simply refill diesel according to the manual and open the fuel tank breather valve. 3. The fuel supply line or diesel filter is clogged. At this point, clean the fuel supply line and pipe joint filter screen, drain the accumulated water at the bottom of the diesel filter, or replace the diesel filter. 4. There is air in the fuel supply system. In this case, unscrew the air bleed plug on the diesel filter, pump the hand lever of the fuel transfer pump several times to exhaust the air, then tighten the air bleed plug, and check whether all fuel pipe joints are tightened. 5. The cylinder head gasket leaks air. At this time, it is necessary to retighten the cylinder head bolts according to the specified torque and sequence. Also, check whether the cylinder head gasket is damaged. 6. Poor sealing between the valve and valve seat. In this case, remove the carbon deposits between the valve and valve seat, and if necessary, grind the valve and valve seat or mill the valve seat ring.
Having run an auto repair shop for years, I've found that engine air leaks are often caused by worn piston rings leading to poor sealing. After high-temperature operation, the ring gaps expand, allowing gases to escape from the cylinders and reducing compression efficiency. Damaged cylinder head gaskets are another common issue—aging or overheating can deform the gasket, causing leaks where coolant might mix in and cause corrosion. Valve problems like carbon buildup on valve seats or aging seals can also result in air leaks, affecting intake and exhaust flow. A clogged crankcase ventilation system or failed oil seals may worsen leakage, triggering engine knocking and increased fuel consumption. Regular oil changes for proper lubrication and periodic compression tests for diagnosis are recommended. Address leaks early to prevent catastrophic engine failure. Maintaining these details can save significant costs.
