Yamaha 90hp

[bill moran]

My neighbor has a Yamaha 90Hp year 1987. He suddenly lost power while running on the river. He was getting frequent popping from the engine and a great loss of power. When he got home we pulled the spark plug wires and determined the problem was in the bottom cylinder. We then pulled the spark plug it was loaded with water. We checked spark and it was equal to the other two. <br />So we decided it was a blown head gasket and pulled the head. In the head is a small 1/8" hole.<br />there was no evidence that the gaskets where blown, but the clyinder walls where heavly rusted(salt water)and scored.<br /><br />1. What is the reason for the pinhole?<br /><br />2. How is water kept out of the clylinder with this hole?<br />3. With loss of compression from the scoring will that cause the water intrusion and loss of power?

 

[butlp]

Re: Yamaha 90hp

Boy, this does not sound good!!! <br />I personally have no idea what the problem is but I don't think there should be a hole in the head that lets the water in.<br />Sounds like corrosion!<br /><br />At least this will put you up to the top where the experts will see it.