Winterizing fluke

[Deadline]

Yesterday I had to re-winterize my 2001 Yanmar 2GM because of a hard freeze. The engine must have a high heating threshold because it took 20 minutes of idle and 20 minutes of 2000 RPM to get the pickup line to take in raw water.

I have a T-valve installed after the jar to pour the antifreeze in by funnel. As before, the antifreeze doesn’t go in readily, yet the engine continues to perk along.

I experimented by opening the raw water valve halfway, and sure enough the anti-freeze went in, albeit diluted further.

This raises several questions...

How can engine run 40 minutes without sucking in any water?
Why doesn’t anti-freeze go in once the engine is warm?
Could anti-freeze have gone the other way, out the thru-hull?

 

[Maine Sail]

Whoa!!

Yesterday I had to re-winterize my 2001 Yanmar 2GM because of a hard freeze. The engine must have a high heating threshold because it took 20 minutes of idle and 20 minutes of 2000 RPM to get the pickup line to take in raw water.

Raw water intake could have been frozen??

I have a T-valve installed after the jar to pour the antifreeze in by funnel. As before, the antifreeze doesn’t go in readily, yet the engine continues to perk along.

A tee valve used in this manner can also suck in air causing the pump to become air bound..

I experimented by opening the raw water valve halfway, and sure enough the anti-freeze went in, albeit diluted further.

The change in water pressure probably caused it to become un-air bound.

This raises several questions...

How can engine run 40 minutes without sucking in any water?

It SHOULD NOT!!!!! Can it? Yes, but YOU should never let that happen!

Why doesn’t anti-freeze go in once the engine is warm?

If your engine is raw water cooled this makes more sense if it has an HX the intake hose probably needed to thaw!

Could anti-freeze have gone the other way, out the thru-hull?

Yes if your pump was air bound you could have been pouring the anti-freeze right out through the seacock.

I have posted directions on how to use an in/out bucket here before it is wise to use one. Having an open tee is never a good idea..


Is your engine fresh or raw water cooled? My guess is that your contraption is allowing air into the system and the pump has become air bound and worn out the impeller. Change the impeller...

Either way you should NEVER let any wet exhaust boat engine run for more than a few minutes without water being sucked into the engine and passing out through the exhaust or you could literally melt your exhaust hose and possibly start a fire! the raw water is NOT just to cool your engine it also cools the exhaust hose and exhaust system..