How to Clean the Head Gaskets on 4.2 Liter six cylinder engines.
The 4.2 liter engine was modified a long time ago, and as part of the modification several of the head studs actually sit in the water jacket. This allows the studs to come in contact with the engine coolant, necessitating the use of antifreeze with anti-corrosive properties rather than just plain water. Over a period of years, the studs will corrode and the corrosion will build up and push the head up from the block surface. When this happens, the only cure is to remove the head, clean up the corrosion and replace the head gasket.
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