Overheating and White Smoke

[senseipower]

On my last day sail this year I ran out of wind and had to motor back. After about 3 miles my overheating alarm went off. I shut it down and went to investigate. I could not see much so I waited awhile and restarted it the alarm was still on but I went a little further. Suddenly white smoke came out of the exhaust and then filled the engine compartment. I shut it off and just waited for the wind to pick up and sailed home. Today I replaced the impeller in the water pump. It was faulty. I started the engine and white smoke filled the engine compartment again. It looks like it is coming from below the intake manifold from a fitting - possibly the coolant drain cock. Its like a white diesel vapor. The engine is a YSM12. HELP! HELP! Does anyone out there know why this is happening and how I can fix it?

John

 

[MrUnix]

White smoke == Steam

I'm not familiar with your engine, but I have been wrenching on motors for most of my life. "White Smoke" is usually steam and indicates a coolant system failure (leak) somewhere, and would also explain your overheating problem. If it's coming out your exhaust, then somehow coolant is getting into the combustion chamber; typically an indication of a blown gasket (head and intake manifold gaskets are the most common). If you think it's coming from around the intake manifold or drain cock externally, then you need to clean the area up really good so you can run the engine and examine the area for leaks.

I doubt it would be as much a problem in a marine application, but if you have a blown gasket and coolant has made it's way into the exhaust, be prepared to see it smoke for a while after the repair. The coolant needs to steam off completely and any remnants left in the exhaust will linger for a while. I had an old Chevy truck that blew a head gasket on it's 350ci V-8. After the repair, the thing still blew out thick white smoke from the exhaust for several hours. There was a lot of coolant trapped in the muffler and catalytic converter and it took what seemed like forever to finally blow it all out. It really gave me a scare at first, as I thought that the new gasket was failing as well and I was going to have to tear it all down again.

Cheers,
Brad