Oil leaks are one of the most common automotive concerns for drivers everywhere. Tracking them down can be time-consuming because internal combustion engines have so many components that can fail and cause leaks. When a customer comes to you trying to figure out where the oil on their driveway is coming from, run through this checklist of the top 10 sources of oil leaks.
Oil Pan Gasket: Some vehicles have a gasket that seals the oil pan to the bottom of the engine. It can degrade over time due to heat and age, which eventually leads to leaks. Others use RTV gasket makers/silicone sealants, which can also wear over time and lead to leaks.
Valve Cover Gaskets: Located at the top of the engine, valve cover gaskets seal the valve covers to the top of the cylinder head. These gaskets, or their equivalent silicone seals, are common leak sources, often due to wear or improper tightening.
Oil Filter: The oil filter can become a source of leaks if it’s not properly sealed or if the filter itself is damaged.
Oil Drain Plug: Located at the bottom of the oil pan, the drain plug can leak if it’s not tightened sufficiently or if the washer is damaged or missing. Many modern vehicles with plastic oil pans require the plug to be replaced with every oil change. If your customer hasn’t followed this guidance, the old plug could be the cause of the oil leak.
Crankshaft Seals: These seals are located at the front and rear of the crankshaft. They can become leak points, especially as the rubber ages and cracks. The area in the back of the engine where the crankshaft connects to the transmission is the rear main seal, which is one of the most common – and problematic – areas from which oil leaks can originate.
Camshaft Seals: Similar to crankshaft seals, camshaft seals can deteriorate over time and start to leak.
Head Gasket: Although not as common for oil leaks compared to coolant leaks, a failing head gasket can sometimes allow oil to escape.
Oil Cooler Lines: In vehicles equipped with an oil cooler, the lines connecting the cooler to the engine can become sources of leaks.
Timing Cover Gasket: This gasket seals the front of the engine and can leak due to wear and tear.
Turbocharger: In turbocharged engines, the turbocharger can sometimes be a source of oil leaks, either from the seals within the turbo itself or the oil lines feeding into it.
