What Causes Oil Leakage Under the Engine?

[LaGenesis]

The causes of engine oil leakage are as follows: 1. Oil pan gasket damage or loose screws causing oil leakage. 2. Oil pan drain plug gasket damage, missing, or looseness leading to oil leakage. 3. Improper installation, damage, or loose screws of the timing gear cover gasket causing oil leakage. 4. Engine mounting plate deformation or poor gasket sealing resulting in oil leakage. 5. Poor sealing of the valve cover gasket causing oil leakage. Here are some precautions regarding the engine: 1. Tighter belts are not necessarily better. Over-tightening the belt not only causes it to stretch or break, shortening its service life, but also leads to excessive tension, resulting in deformation and bending of the generator shaft, water pump shaft, and early bearing damage. The tightness of the car engine fan belt should meet technical requirements; generally, a deflection of 10-15mm during normal belt installation is appropriate. 2. If the thermostat is blindly removed due to high engine temperature, the coolant can only circulate in a large loop, unable to regulate cooling intensity, making it difficult to ensure the engine operates at an optimal temperature. Instead, the engine will frequently operate at low temperatures, leading to reduced power, accelerated wear, and increased fuel consumption. 3. Low engine temperature is also highly detrimental. Driving at the normal temperature specified in the car's manual ensures the engine's service life. 4. When warming up at idle speed, due to the low speed, the oil pump cannot quickly press lubricating oil into all lubrication surfaces, and the oil pressure is also low, causing engine moving parts to operate under dry or semi-dry friction conditions. Poor fuel atomization at low temperatures allows unburned fuel to enter the crankcase, washing away the oil film on the cylinder walls, which also accelerates component wear.

[StRobert]

I've been driving for 20 years and have seen many cases of engine oil seepage. The most common issue is the oil pan gasket aging - this rubber component hardens and cracks over time. Also, the drain plug washer may deform or not be tightened properly during installation, leading to leaks after oil changes. If the front or rear crankshaft oil seal fails, it's more troublesome as many parts need disassembly for repair. A deteriorated valve cover gasket can also make oil drip down from above, appearing like a bottom leak. My advice is to first clean the leaking area, drive for a few days, then observe where new oil stains emerge. Don't panic about minor initial seepage, but do check oil levels regularly with the dipstick. If it's leaking like dripping rain, get it fixed immediately - engine damage from oil starvation would cost much more to repair.

[LaMakayla]

A couple of days ago, I also noticed an oil stain under my car and panicked, rushing to the repair shop. The mechanic said my car is over five years old, and it's likely due to natural aging of rubber seals. He used a flashlight and found the leak at the oil pan seam, saying the gasket had hardened. He also warned me that hitting speed bumps too hard causes excessive vibration in the oil pan, accelerating the leak. He explained that if the leak were near the transmission, it could be a rear crankshaft seal issue, which would require removing the subframe—a time-consuming and labor-intensive job. Later, I bought a bottle of engine degreaser to clean it up, and now I check under the car weekly. The oil level hasn’t dropped, and the mechanic said this issue can wait until the next maintenance, but I should monitor if the oil stain spreads.

[VonMarley]

When dealing with oil leaks under the engine during car repairs, I mainly encounter four common issues. The oil pan gasket sealant becomes aged and cracked, especially in vehicles with over 100,000 kilometers. Repeated use of the drain plug washer causes deformation and oil leakage. Worn-out front and rear crankshaft oil seals lead to oil seepage. Loose installation of the oil filter or damaged sealing rings can also cause leaks. The color and consistency of the oil stains can help identify the source—thick, dark brown stains are usually engine oil, while thin, light-colored ones may indicate coolant. If you notice a leak, first check the oil dipstick to see if the level has dropped; maintaining the oil level at the midpoint is ideal. If the leak progresses to dripping, prompt repair is necessary to prevent minor issues from turning into major problems.