1985 johnson 150 compression ratings

[85Skeeterman]

I have found that there is a lot of discussion concerning what the compression should be on a 80's model 90 degree cross flow Johnson- Evinrude 150 GT-XP engines.

I purchased one in 1985 and the compression on my engine at that time was around 120 psi It wasn't long after that that it was difficult to find leaded fuel. I went to a OMC dealership to ask what I could do to prevent damage to my engine when running lead free fuel.

I was told that OMC solution to the problem was to install new head gaskets that were thicker and reduce the compression to keep from burning the cylinders.

I purchased and installed the new head gaskets to find that they did indeed lower the compression to around 85 to 90 psi per cylinder.

I would assume that the later 80's model engines came from the factory with the new type of head gaskets installed.

Just posting this information as it might help to clear up some concerns for 150 Johnson or Evinrude owners with compression readings in 80's to 90 psi readings

Skeeterman

 

[boobie]

Thanks for the info. That was a good memory jogger for me. I remember doing the up-dates but had forgot all about them. Thanks Again !!

 

[Faztbullet]

Head was changed not gaskets on later models...