How To Change a Head Gasket

A failed or broken gasket may manifest in several ways. One of the ways to know that you have a broken gasket is when your engine oil has coolant in it. This is not usually a do-it-yourself activity, because with most engines, the difficulty lies in the actual skill of the mechanic in opening the engine and properly installing a new gasket. Therefore, even if the head gasket itself is a relatively inexpensive auto part, it's the labor cost that is big, not to mention the time involved in the actual work.

Due to the variety of cars and engines available, there is no one way to change a head gasket. The exact procedure differs, for instance, from an overhead-camshaft (OHC) engine, to a internal camshaft engine. It also differs if you're working on an inline engine or a V6 or V8 configuration, in which case, you will have to replace two sets and not just one.

  1. Before working on the engine block, be sure it's cool enough. You also need to disconnect the battery terminals and drain the cooling system. You will also need to raise the front end of the vehicle on jack stands to access the exhaust manifold at the bottom. Remove the exhaust volts connecting the exhaust manifold to the exhaust pipe.
  2. You can now lower the vehicle, and open the hood. Remove the air cleaner assembly, the upper radiator hose, and then the thermostat housing. You should also take out the high tension wires from the spark plugs. Once there are no obstructions, you can now remove the valve cover.
  3. Upon the removal of the valve cover, remove the rocker arms and push rods. Place these parts in a safe place so that they can be replaced back to the engine in good condition. On the other hand, if you have an overhead cam engine, you also need to remove the timing cover and timing belt or chain. The valves may not be manually removed as the cam and valve assembly are more likely to be removed together with the head, depending on your engine make.
  4. After gaining access to the head bolts, loosen them in order. Starting from inside, slowly loosen the bolts in a spiral pattern, and store these in a safe place. If they are of different kinds, you need to remember where they were loosened from. Once you successfully remove all the bolts, you have to break the head loose from the gasket and remove it from the engine compartment. The gasket is sealed inside the block, and the head you might have to gently hammer to loosen it up from the engine block.
  5. Once the head is removed, you are now ready to install a new one. Before doing so, you need to make sure that the gasket material from all the surfaces is removed. You can use a metal scraper to remove this residual material, and then clean the surface with a solvent.
  6. Install the new gasket and the head into the proper slot. This should be done carefully and properly to prevent future failures and damages. After placing the gasket and the head, you may now screw the head bolts on as tightly as possible. After securing the head in place, reinstall all the parts that you removed during the replacement.

The head gasket is regarded as the most important sealing application inside a car's engine. Several forces make this part wear out or break apart. Before trying to replace a blown gasket, though, try checking other areas of the engine for other possible sources of engine problems. In all likelihood, you might have to take your car to a professional due to the complicated nature of gasket replacement, unless you have extensive experience in engine repair.


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