I have a 1989 Jeep Cherokee with 218,700 miles on it and my engine has thick oily gunk on it, possibly from a leaky valve cover gasket, should I change the gasket? I have been told that this is normal and not to worry about, but from the amount of this gunk, I find it hard to believe this is normal. The top of the valve cover has a light covering of gunk, but on the sides and towards the bottom of the engine. it gets very thick and at some places you can't even make out whats suppose there. Does a leaky valve cover gasket mean that there is another problem going on?Can leaving the oily gunk on the engine cause any problems?Any info would be greatly appreciated.
Usually, a leaky valve cover gasket is just that. A leaky valve cover gasket. Unless you are building up high internal pressure from a clogged PCV for example and literally forcing the oil out the weakest point, there usually is no underlying issue. Leaving the oily gunk does a couple things. If its on rubber such as any hoses that aren't oil resistant, they will degrade quickly. The same can goes for wiring insulation, motor mounts, or even the rubber seals on some of your front end pieces. Also, wrapping an engine in a thick layer of goo doesn't let it cool as it should and puts more thermal burden on it. What you do at this point is a question of how much longer a 1989 Jeep with 218,700 miles will go or how much longer you want to keep it.
Not to be mean but you can't work on what you can't see! Take the Jeep to a wand type car wash with a bag of quarters. Lift the hood and spend some time with high pressure soap and clean the entire engine and under-hood compartment. Don't bother covering anything. Leaking valve covers don't mean anything is wrong, it just makes a nasty mess. Remove valve cover/s and scrape old gasket material of the head/s and cover/s. The best valve covers in the world won't seal until the valve cover/s are completely flat. *This is an age old problem with stamped steel covers. If you want to get extra slick, chase down some aluminum cover/s. There stiffer and less apt to leak when you snug them back down. I'll let you in on a racers secret to make them seal. Buy a tube of Dow Corning or Permetex clear RTV silicone sealer. Scrape down the valve cover gasket surface till it's clean. Wipe the gasket surface down with CRC Brake Clean. Run a bead of the clear RTV on the valve cover and let it set-up for at least five minutes. Lay a Fel-Pro - Blue Stripe valve cover gasket on the valve cover. Seat it with your thumbs. Scrape-down the cylinder head where the gasket goes till it's perfectly clean. Clean the gasket seating surface on the cylinder head with C5RC Brake Clean. Lay a small bead of the RTV on the outside of the gasket which will meat the cylinder-head. Carefully set the cover on the head and gently alternately tighten them. It's OK to drive the vehicle as soon as you're done!
DIY method: pressure wash engine with a degreaser solution, remove valve cover, clean mating surfaces, apply a RTV silicone compound to the valve cover and install new gasket, reinstall valve cover, reinstall bolts taking care to not overtighten them, replace PCV valve (probably a good reasson why it leaks to begin with) clean jobsite and drink a beer. Non-DIY method: take to shop and pay about $150 for the trouble. Not a good idea to ignore an oil leak, it's just not.
take to car wash pressure blast as much gunk off. then replace the gasket, no it's not normal and yes it is the gasket( most likely- sight unseen) gaskets will go bad over time, it's man made.
Valve cover gasket start leaking over time. That is normal. The thick oily gunk is from years of engine neglect. It doesn't happen over night. It's a good idea to clean the engine once in a while. As for the valve cover gaskets, they should be replaced (should have long ago) to prevent any more oily gunk from building up.
