Change a Valve Cover Gasket on a Car
Valve cover gaskets will age over time and become brittle and once that happens you will lose the correct pressure you should have between the cover and the engine block ultimately allowing oil to leak through. Changing the gasket is not a very tough job although some car designs will make it a bit more complicated and you may have to remove additional parts to get to the gaskets. This eHow describes change the gasket under the assumption that you already have access to all the hold down bolts and clearance to remove the cover.
1. Remove all of the hold down bolts holding the cover in place. Be sure to remove them straight and not strip the heads, making sure you are using the right size wrench or socket. If you have a problem with any, spray some Rust Buster or penetrating oil on the bolt, wait a little bit and try again.
2. Usually the cover will just lift right up and off, but sometimes, even though all the bolts are off, the cover will be stuck on. This is the gasket still hanging on from the original seal.
3. try to slip the edge of your putty knife under a corner and pry up some if the cover does not lift right off at first. You may have to tap the end of the knife with a hammer to gain a wedge to work with. If you get a corner loose you can slip your flat head screwdriver in the opening and then just twist the screwdriver to pry it free. Other times you may gently tap on a corner of the cover with a rubber mallet to break the seal. It will come off, but you may have to work it a bit. Whatever you do, do not force anything and risk bending a corner of the cover or denting it.
4. Scrape off the remaining gasket sealer once the cover is removed with either your putty knife or razor blade. Then using your sand paper, gently sand the mating surface for perfect smoothness. You should not have any gasket material or debris on the surface.
5. Cover the open area of the engine that is now exposed since you took the cover off with either paper towels or clean rags to be sure that no debris gets inside and then clean and sand that mating surface the same way as you did for the cover. Both mating surfaces should be very smooth and bump free.
6. Test fit the new gasket by placing it on the engine block to be sure it is the correct size and the holes line up perfectly.
7. Apply your gasket sealer on the engine mating surface approximately 1/8 inch thick covering the entire surface and wipe off any excess around the edges. Let the sealer set a few minutes and get slightly tacky and then place the gasket on, lining up the holes on the gasket with those on the engine block.
8. Apply a thinner layer of sealer on the top side of the gasket. Wipe off any excess sealer and let set a little bit to get tacky.
9. Remove your paper towels or rags you placed earlier to protect the engine parts. Place the valve cover onto the gasket trying to place it correctly the first time so you don’t have to slide it around much and disturb the sealer.
10. Spray or soak the hold down bolts with WD-40 being sure there is no debris in the threads and then tighten them down according to your specific torque using a crisscross pattern rather then one side at a time.
11. Clean up any gasket material from the lower sides of the gasket area on the engine block and then run the car for a few minutes watching for any leaks. After the car is turned off you can run a dry paper towel just below the entire gasket area on the block to see if you picked up any oil, which would mean a leak. If this is the case it could mean one of three things. 1) The bolts are not all tightened down evenly according to torque. 2) The valve cover is warped and not setting flush. 3) There is debris or old gasket material either on the engine mating surface or on the valve cover. It is critical to have a baby smooth surface on both mating surfaces before installing the new gasket and sealer.