Disappearing engine coolant

[CrazyLegs]

On our odyssey to get our boat back home to BC. Having run the Yanmar 4JH4E for @ 90 hrs thus far and notice the level of coolant in the coolant reservoir is going down. Where could it be going, this is a closed loop system? No white smoke coming from exhaust.

 

[Delezynski]

On our odyssey to get our boat back home to BC. Having run the Yanmar 4JH4E for @ 90 hrs thus far and notice the level of coolant in the coolant reservoir is going down. Where could it be going, this is a closed loop system? No white smoke coming from exhaust.

Just had a similar problem. :cry:
I posted a short Youtube about it at;
https://youtu.be/wkr5Iw7S33I


Greg

 

[Tim R.]

I had a similar issue on my '97 4JH-2E. The leak was happening in the exhaust manifold/heat exchanger. Yanmar designed the wall between the exhaust ports and fresh water side too thin. A pinhole had developed and the coolant was leaking into the exhaust port and going overboard with the raw water. The leak started very small and I nursed it for months until it became much larger and I had to tear the engine down to find the leak. When it started leaking badly you could smell the coolant in the exhaust. I had to replace the entire housing for about $1000. The new housing is about twice as thick in that area.

 

[richk]

Had a similar prob on our prev boat...H35 with 3GM30F. Loop from engine through water heater used hose which ran through a stringer. Over time a hole wore through the hose at hole edge, dripping antifreeze into liner. What a mystery until we discovered it. We kept adding fluid which disappeared....no obvious leaks. Actually we didn't discover it, our mechanic did. He enlarged stringer hole (so no rubbing), replace hose, refilled system. Ran like a champ.

Backstory...it happened on one of those trips where we'd found the perfect anchorage. Everything was beautiful...protected, deep enough water, perfect weather. Stayed two nights. Went to go home (about 6 hours away). Temp alarm blasts. Thought it was debris in seacock...not! Saw coolant was low (read non-existant.) Nursed the engine home with her on wheel and me down below feeding fresh water from tank to beaker to coolant reservoir. Twelve hours later we pulled. Whew!