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If you shut off your car and notice the distinct, smoky smell of burning oil, it means you have an oil leak. Oil leaks can originate from many different places around the engine, but one of the most common spots for an oil leak is at the valve cover.

No two pieces of metal are ever machined with surfaces that are completely smooth and that will mate with absolutely no leaks. That’s why gaskets are necessary. The valve cover encloses the valves, valve springs and rocker arms (on some engines), protecting them and keeping lubrication sealed in. The valve cover gasket, then, is mounted between the cover and the cylinder head, sealing the joint between the two. Over time, like many gaskets, the valve cover gasket can shrink, dry out or crack, allowing oil to leak out.

On some engines, replacing the valve cover gasket is fairly straightforward. On many, however, it can quickly turn into a fairly involved job. V8 and V6 engines, particularly in a cramped engine bay, can pose a real challenge, with poor access and many cables, vacuum lines, hoses and sometimes entire parts or assemblies that may have to be moved out of the way and then replaced at the end of the job.

It’s important that the mating surfaces be absolutely clean before installing the new gasket, and this is a detail that many home mechanics miss. Any remaining bits of old gasket material will mean a poor seal, as will any gouges or deep scrapes in the surfaces (which can easily happen while using a metal scraper rather than plastic). The surfaces need to be thoroughly but gently scraped, then cleaned and wiped with a solvent like brake cleaner before installing the new gasket.

Many home mechanics also have a tendency to over-torque the valve covers’ hold-down bolts, deforming the gasket and possibly even bending the flange of the cover and starting a fresh leak.

If you suspect you may have an oil leak, it can be tough to track down, especially on an older vehicle that has a grimy engine block and heads. On the lower end of the engine, leaking oil may be blown backward from wind passing through the engine bay as you drive. One mechanic’s trick to pin down the location of the leak, though, is to use brake cleaner to clean off the dirty area, then spray athlete’s foot powder on the area where you suspect the leak may be originating from. Within a day or so, the leak should be apparent against the white powder.

Here’s the thing about valve cover gasket leaks, or any other oil leaks – they don’t just get better on their own, and the stink of burning oil on a hot exhaust manifold is pretty unappealing. Don’t just put up with it and keep adding oil that’s being bled out through the valve cover gasket. Give us a call and make an appointment at Master Auto Repair in St Louis, MO.