1986 Johnson 150 powerhead

[bill9259]

I have a 1986 Johnson 150 engine that I bought knowing it had problems. when I pulled the engine apart I found all of the pistons on the right side bank of the engine scored. The bores in the block were scored as well. Further inspection showed a lot of corrosion around the cylinder liners from salt water. I threw this block aside and purchased another used powerhead that came from a fresh water application. I bored this block .030 over to use a new set of pistons I had and have reassembled the powerhead. From reading this forum I know I have repaired the damage but now must be sure I have found what caused the scoring of all the original pistons on the right bank. I suspect the right bank had a head gasket problem due to the corrosion at the top of the cylinders. I don't think this would have damaged all three pistons. I will be cleaning the carbs to make sure I have no clogged fuel passages. I am also using a new VRO pump. I am looking for any input as to anything else I should be checking or repairing before starting this motor. I do not want to score the pistons and bores in my new powerhead.

 

[Joe Reeves]

Re: 1986 Johnson 150 powerhead

It's possible that the corrosion, which could have resulted in a head gasket sealing condition, could have caused a fine water spray that would have led to scoring on that one bank.

However, I would be leaning towards weak ignition on that bank. This would lead to faulty combustion of the fuel which would eventually lead to what is usually termed a "washout" whereas the gasoline overcomes the oil leading to friction etc. If that stator is a 35amp stator, look closely at the large black coils for cracks, a sticky substance leaking out of either of them. This melt down would result in a voltage drop to the powerpack(s).... in the case of dual powerpacks, usually just one of them is affected initially.