12HP Lawnmower Head Gasket Question?

Question

I have a 1986 Wheel Horse Riding Lawnmower. When I took the cylinder head off to clean it up I noticed that the head gasket had two small spots that where blown off of chiped off. It wasn't the entire way throught it. If was chiped off on the outter side of the Gasket, not the inside part that is nearest the piston. Then when I looked at the cylinder head I noticed that there was a little bit of black in the outside of it where the gasket was chiped. Could this cause the engine not to run right and lose power, even though it's not a full hole in the gasket?

Thanks for the help!

Also what could of caused this?

Answer 1

If there are black streaks where the chipped area is, then the gasket was leaking & should be replaced.

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Answer 2

If the compression was not leaking from around the fire ring of the head gasket, then it was fine.

Answer 3

Inspect very carefully the sealing surface of each valve and valve seat. They are easy to remove to clean or replace. Try to remove all the carbon from the combustion camber of the cylinder head  with a drill powered wire brush.

For a few bucks buy a new head-gasket. If you have a flat thick piece of glass, lay down a sheet of 220 wet and dry sand paper. Using a black magic marker color the sealing surface of the head. Rub the sealing surface of the head in alternating directions with your hand. Turn the head in your hand several times as you rub it back and fourth. Keep checking the magic marker to see if the surface totally cleans up.

Don't fret too much about carbon on the piston because if you try to clean it off junk may wedge down in the top piston ring groove.