What are the common causes of engine oil leakage?
2 Answers
The causes of engine oil leakage are: 1. The cylinder head gasket between the upper and lower cylinder blocks is burned through, causing lubricating oil to seep out (located in the upper middle part of the engine); 2. Insufficient adhesive at the connection between the lower cylinder block and the base cylinder block, resulting in gaps that allow oil seepage; 3. Uneven application of sealant between the oil pan and the engine block, creating weak points that may crack and leak oil after prolonged use; 4. Sand holes or cracks in the cylinder block or oil pan. The main hazards of engine oil leakage are oil loss and waste, and in severe cases, it may lead to insufficient oil levels, potentially causing engine damage. Therefore, it is crucial to monitor the oil level closely. Most vehicles are equipped with oil level indicators, which help prevent unnoticed drops in oil levels below normal, and an oil pressure warning light will alert the driver if the oil pressure is insufficient.
With over a decade of engine repair experience, I've found oil leaks most commonly occur in a few key areas: The valve cover gasket aging and cracking causes the most noticeable leaks, as rubber components can't withstand hot engine oil. If the front and rear crankshaft oil seals wear out, oil sprays outward as the crankshaft rotates. Then there's the oil pan gasket deforming or the drain plug not being tightened properly – leaks from these two spots form oil drips on the ground. The most overlooked issues during repairs are misaligned oil filter housing O-rings or insufficient sealant application on timing chain covers. I once encountered a vehicle where oil seepage was actually caused by a deteriorated oil pressure sensor O-ring, yet the owner mistakenly thought it was an oil pan issue. My advice: When detecting leaks, first wipe the oil residue clean, then start the engine to pinpoint the exact leakage source more accurately.
