|Putting a Cap on Oil Leaks -|
An engine that's burning oil spews obvious signs and signals. Clouds of smoke at startup or when getting on and off the throttle visually show where that quart of oil every 500 miles is going. If the dipstick is reading low and there's no sign of oil smoke, suspect an oil leak. While the source of oil leaks can be hard to locate, a common and relatively easy to repair source is located where the valve cover meets the cylinder head. If oil is going missing and the area around and under the valve cover is soaked then it could be time to replace the valve cover gasket.
Intake and exhaust valves open and close at rapid rates while the engine is running. This action makes for mechanical mayhem under the valve cover. This thrashing about creates and requires a hot oil shower for lubrication. The valve cover gasket sits between the engine and the valve cover and seals the oil inside. Time and many miles can dry out or crack the valve cover gasket. If the seal created by the valve cover and valve cover gasket loses its ability to contain all the oil flying around inside then oil will escape. Valve cover bolts can also work their way loose. Valve covers can also warp or crack.
Locating oil leak sources can be tricky. The telltale sign of a valve cover gasket that has lost its seal is an oil-covered valve cover or a burning oil smell when the engine is running. As oil leaks from a valve cover it can contact a hot exhaust manifold and burn. Smoke can then waft into the cabin. Oil from a leaking valve cover can also travel down the back or side of an engine and mimic a leak from somewhere else such as the rear main seal or oil pan. An inexpensive telescoping mirror can help locate otherwise hidden valve cover oil leaks. Start looking at the top and follow the oil trail. A valve cover can leak oil while the engine is running, but not while the engine is at rest. The action of the valves kicks around a lot of oil.
If a valve cover oil leak is suspected, monitor the oil level closely until the source of the oil leak can be found and repairs made. Running an engine low on oil can be a disastrously expensive mistake. A valve cover leak can get worse as engine revolutions increase. The action of the valvetrain makes for a bigger oil bath. At high revolutions the engine can spew a great deal of oil while in operation and leak very little at idle, or none at all while at rest. Replacing a valve cover gasket is fairly basic but the procedure varies by engine. The toughest part is usually getting to the valve cover itself.