How to Determine if an Oil Leak From a Car is From the Valve Cover Gasket

by braniac

Do you smell oil burning on the engine block and find drips or puddles under the car after it has been parked for a while? Tracking down an oil leak is really a process of elimination for there are a number of sources. One possible source is that the oil is leaking out through a bad gasket seal between the valve cover and engine block.

Locate the gasket between the engine block and valve cover. You should be able to freely run your finger tip along the entire seam and may have to detach wiring clips or small parts to gain this access.

With safety goggles on, spray the degreaser from above the gasket edge down along the side of the engine block. Carefully hose or wash the degreaser off. The object is that you want a clean and dry surface from just above the valve cover gasket and down the engine block at least four to six inches. Degreasing under the car where the oil may be dripping from is not necessary.

A leak from the gasket will only occur while the car is running or after you have first turned it off, so you need to run the car for five to 10 minutes or take a short drive.

With the hood open now to help cool down the engine, you want to check for oil leaks as soon as possible without burning your arms or hands, and yet not giving the possible leak too much time to completely dry up by waiting too long. Take a dry clean rag or heavy paper towel and using your flashlight or direct lighting slowly drag and dab the cloth along every inch of the gasket area and also just below it, checking often for any oil on the rag.

If you picked up any oil on the rag, you have located your leak and should notate the exact sections you found the oil. If the rag turns up dry and oil free, your leak is coming from somewhere else.


  • check In some cases, the reason for a valve cover gasket leak is simply because hold down bolt(s) have become loose, and the seal isn't tight. Re-tightening all the bolt(s) according to proper torque may stop it. In other cases, the gasket is simply old and brittle and needs to be replaced. Yet in other cases, the gasket seal and torque is fine, but because of another issue, such as a bad PCV valve or kink in the rubber hose, causing un due pressure or also referred to as "blow back", oil is being forced back out through a weaker link, which could be a valve cover gasket. If this is the case, repairing a line kink or replacing the PCV may stop it. Finally, if the valve cover itself is warped or damaged, you would need to replace the cover and gasket.


  • close Be careful not to burn yourself on the hot engine block when checking for the leak.
  • close If you tighten down any loose hold down bolts on the valve cover, you should make sure they are "all" torqued evenly or you can warp and ruin the cover.

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