Hello,


I installed a pressure gauge onto the cooling system when I suspected a blown head gasket. I installed a tee onto the coolant tank reservoir line and ran a plastic tube to the dashboard so I could see what was happening during operation.

I noticed that when I first installed the gauge, there would always be residual pressure in the coolant system. During operation, the pressure would rise until opening the new green coolant tank cap, about 20 psi. Also, I noticed that the pointer would move in response to engine vacuum. The only way this could have occurred was a defective head gasket or cracked casting.

Weeks elapsed, and when I pulled the plugs and noticed that the first plug was cleaner then the rest. By this time, the gauge would quickly rise to the cap opening pressure, about five minutes of operation, and the gauge pointer was greatly influenced by the engine vacuum.

Upon removal of the cylinder head, I noticed that the large ported coolant passages on the #1 cylinder were cut without much margin for the gasket. The top of this piston was clean, the others were not.

I replaced the cylinder head with a small coolant passage design and now the gauge doesn't do much. It will reach 5# on a hot day and is not influenced in any way. I also noticed that I'm not adding coolant anymore.


Goatman