Cadillac Repair: 91 cadillac, head gasket leak, debris buildup

Question
The car had a head gasket leak between the water port and the cylnder, so I pulled the heads & had them shaved then reinstalled them to spec. Now when I start the car it runs rough, so I pulled the plugs and they have like a black dusty carbon on them. My ? is what could be making it run rough now. I don't believe it's a vacuum leak but I could be wrong.Oh it also taps a little now. Please help. thanks....91 cadi, deville 4.9

Answer
The tapping is most likely being caused by a lifter that is partially stuck from the water contamination of which will require removal of the lifter and disassembling it and cleaning it or replacing it. STRONGLY recommend doing all the lifters on this bank.

When you pulled the head and found a carbon buildup on top of the pistons did you use a solvent to remove it ?>

If NOT, Try using a product called TOP ENGINE cleaner and follow the directives on the product.

I would also recommend a compression test and a cylinder leakage test on ALL the cylinders just to make sure that you do not have any cylinder problems. Do ALL 8 cylinders just to check for differences.

Water and or anti freeze getting into the combustion and oil system of any vehicle causes numerous problems due to contamination and debris buildup within the lifters.


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