Mechanic called and said when he was winterizing the boat by pumping antifreeze in it the starboard motor started smoking badly. He said it was probably do to the antifreeze being burned. Motor is a 1996 502.
I never noticed any milky looking oil on the dipstick. Engine never ran hot.
Boat has been sitting for about a month.

Any ideas on where to start to look for problem?

Thanks,

FINMAN

It is normal for motors to smoke when they are running anti-freeze through the exhaust.

Was it smoke or was it actually steam?? Mine will do that because of the reduced flow of antifreeze as compared to water. The exhaust gets hotter (and I'm usually doing it as it's getting cold too) so the cooling medium will steam from the additional heat.