moisture in PCV tubes

[Rich Novak]

1972 omc 225 sterndrive electric shift I have a overheating problem . At low rpm no problem. Around 3 k rpm it starts to climb. I noticed steam ? / moisture coming out of the pcv tubes going to carb. Thought that was the reason for backfire at high rpm disconnected tubes no diff. Logs have been cleaned with acid. New impeller and water pump. Starts on a dime . only backfire with a load. No load no backfire all the way past 5k rpm. Thanks Rich.

 

[Rich Novak]

Anyone

 

[Howard Sterndrive]

compression test the motor would be the first thing to do.
If rings are worn out, a lot of combustion gases end up in the crankcase and the vapour in it has to escape via those tubes.
If the compression test is good, I wouldn't worry about it too much. Could try a different brand of oil. Make sure the engine is getting up to temp (140 minimum).

Backfire at high rpm could be timing related but usually means your fuel mixture is leaning out. (especially if it follows a lag or slowing of the engine...running out of fuel due to fuel delivery issues or carb not healthy)

 

[Rich Novak]

Thanks