I have a 98 Mitsubishi Mirage, seems there is a valve cover oil leak, i know this can be easily fixed by replacing the gasket.. but how will i know if the leak isn't from the valve cover gasket . Is the cylinder head gasket a major issue also .. if its not really the valve cover thats producing the oil leak should i not worry and just replace the valve cover gasket .?
Sounds like you should clean your engine, then take a look to see where the leak is. Have you tried tightening the valve cover bolts?.
The valve cover gasket is not as big of a deal, if it gets really bad you will just start smelling a lot of burining oil. The head gasket can become a major issue, especially since coolant also flows through more internal part of the gasket. The question you need to ask is if the leak is closer to the top (valve cover) or farther down the block?
Valve cover leaks are typically characterized by what you're experiencing: oil oozing out from the cover/cylinder head mating surfaces. If this were your cylinder head gasket, then you'd be experiencing some problems with how the engine runs ...very unlikely it would cause oil to leak from the valve cover. *Do not* simply wrench down on the bolts holding the valve cover; all you will do is crush the gasket and create a bigger leak. Two things you need to do: replace the valve cover gasket and make sure your PVC or crankcase vent system is not blocked. Swapping the gasket is pretty obvious ...they get old and dry out and leak. Checking/cleaning the crankcase vent system keeps compression blow-by gases (a normal thing in engines) from pressurizing the crankcase and forcing oil to seep out in places it shouldn't. A healthy, properly working crankcase vent system helps prevent this.
