Steam Coming From Rocker Arm Cover

[MikeSpady]

Ran boat first time this season. Temp gauge showed 160 degrees within 10 minutes. Shut it down and noticed steam escaping from oil cap on the rocker arm cover. Brought boat home and put on ear muffs on the sterndrive and let idle for 30 minutes. Temp guage stayed at 110 and no steam evident. What do you guys think?

Mercruiser 140 H.P. General Motors In-line 4 cylinder, 1969

 

[Haut Medoc]

Re: Steam Coming From Rocker Arm Cover

Welcome to iboats......
I think it may be time for a new raw water impeller.....
The fact that it does not overheat while on muffs suggests that....
If you have no water in your oil, then the steam may just be condensation from sitting......
Did it go above 160?......​

 

[KaGee]

Re: Steam Coming From Rocker Arm Cover

Not uncommon to have condensation in the block if a motor sat for a while. A good run under power for about 20 minutes should burn it all off.

 

[Coors]

Re: Steam Coming From Rocker Arm Cover

And what is your thermostat; 140, or 160?