Compressed air in ventilation hose. 1978 35hp Evinrude

[Randy4s]

I have air coming through the hose that goes from the crankcase to below the carb. It burned a hole through the hose. I replaced the hose, and it burned a new hole in 10 seconds. The motor won't idle, but runs ok at higher rpm. I checked the compression, and each cylinder was 120. The air coming through the hose is not continuous, but more like a blast every few seconds. Ideas? 1978 Evinrude 35hp Model 35802R

 

[Haffiman]

Re: Compressed air in ventilation hose. 1978 35hp Evinrude

You most likely have a crank case combustion.
Normally caused by lean burning.
Check engine temperature, check/clean idle circuit of carb. De-carb the engine.