1. Faulty valve cover gasket. This is one of the most common causes of oil leaks from the upper part of an engine. The valve cover gasket is a rubber seal that fits between the valve cover and the cylinder head. Over time, this gasket can become brittle and crack, allowing oil to seep out.
2. Cracked cylinder head. A cracked cylinder head can also cause oil leaks from the upper part of an engine. Cracks in the cylinder head can allow oil to seep into the coolant or flow out of the engine completely.
3. Blown head gasket. A blown head gasket can cause a variety of problems, including oil leaks from the upper part of an engine. A head gasket is a thin metal gasket that fits between the cylinder head and the engine block. When a head gasket blows, it can allow oil to leak out of the engine.
4. Oil filter housing gasket. The oil filter housing gasket is a rubber seal that fits between the oil filter housing and the engine block. This gasket can become brittle or torn, allowing oil to leak out of the engine.
5. Incorrect oil level. Too much or too little oil in an engine can cause the oil to leak. If the oil level is too high, it can cause pressure buildup that can force oil out of the gaskets. If the oil level is too low, it can cause the oil pump to suck air, which can also cause leaks.
6. Worn piston rings. Worn piston rings can also cause oil leaks from the upper part of an engine. Piston rings are metal rings that fit around the pistons. Over time, these rings can wear out, allowing oil to seep into the combustion chambers and out of the exhaust.
7. Faulty PCV valve. Faulty PCV valve. The PCV valve, or positive crankcase ventilation valve, is a small valve that helps to control the flow of gases from the crankcase to the intake manifold. If the PCV valve fails or is clogged, it can cause pressure buildup in the crankcase and force oil out of the gaskets.
