1972 Johnson mystery

Does anyone know what the 2 t

Does anyone know what the 2 tiny (1/16" round)ports are next to the spark plug holes on the head of a 1972 20hp Johnson? Am I losing compression through these ports? Should the spark plug washers cover these up? I can hear air escaping when I hand crank the motor. My manual does not mention them.

"Gary..... I don't have on

"Gary..... I don't have one of those heads in front of me, and I know the manual says nothing about small 1/16" holes in the head. Frankly I can not visualize that head with those holes in it.

However, if those holes led into either the combustion chamber or the water passages, when running you would have either a strong flame or water shooting out those holes. Unless you encounter one or both of these problems, I don't think it is anything to be concerned about.

Note that piston rings do not make a perfect seal, especially at cranking speed.... and it is very likely that you will hear the compression sneaking by those rings.

Joe "

" I have never seen the "h

" I have never seen the "holes " that are mentioned.But you never know , there is always something new on motors. "

" Gary,

I've noticed si

" Gary,

I've noticed similar holes on my merc 115; I've wondered what they are doing there myself. They are on the area that could be described as the head (this particular engine is headless though). The threaded holes are in very close proximity to the spark plugs. My guess has allways been that it's for some type of temp guage, your guess is a good as mine. The holes do not go all the way through. As for the air escaping - in agreement, if you turn the engine slowly and listen close enough, you will hear it. If the compression is good, there's nothing to worry about. If you want to proove it to yourself, put some grease in the hole and see what happens when the engine is turned over.

Jon "

Thought about this for some t

Thought about this for some time and these "holes" might be a result of a sparkplug thread repair insert being installed.

Well curiosity got the best o

Well curiosity got the best of me and I decided to pull the head off and investigate. And a good thing I did because the compression leak I was hearing was due to a bad head gasket and had nothing to do with the little holes I mentioned. As far as I can tell these holes don't go anywhere. I couldn't force air or water through them. Thanks for your ideas and keep up the good work!