Antifreeze Leak???

[Webone]

I have an Yanmar 50 hp. with 1160 hrs. The antifreeze keeps slowly dropping in the tank with use, approx. 1/8 below full every 6-8 hrs. I cannot find any signs in the bilge or on the engine. Any suggestions on tracking this down would be much appreciated.

 

[Bill Roosa]

the heat exchanger could be leaking anti into the exhaust as raw cooling water.
The hot water heater could be leaking into the fresh water system. You would probably notice a taste in the water though if that is the problem.
You could have a hose leaking slowly. Weeps usually don't show up as the anti boils off before it can become a drip. You should be able to smell anti in the engine compartment though if that is the porblem. After a long time you will see a scale form around the offending hose/nipple junction.

 

[navigator97]

Another possibility is the hoses from the engine to the water heater and it's return. I have had the chafe thru and dribble out. The chaffing came from normal vibration when engine was running and the place where the hoses passed thru the cutout in the fiberglass pan. I had to actually pull the hoses back a bit before seeing the chafe marks. I had looked 3 times before and didn't see it.

 

[Stu Jackson]

How long has it been since you've replaced your hoses and removed your HX for a detailed checkout?

 

[bobtigar]

Look for the simplest things first. That may not be the problem, but you will really feel stupid ( and waste a lot of time if it is something simple...Broken hose clamp? Bob

 

[Webone]

Thanks for the tips. Boat is new to me so I do not when hoses were updated, however they look pretty good. Will hunt down water heater runs after checking all clamps.