6BTA Source of Antifreeze Leak?

[John]

Have a 6BTA 270hp engine in my 2006 Nordic Tug 32+. Boat is in Northern Rhode Island, winterized and on the hard for the Winter. We had below zero temperatures the first week of January, and a few more days through January. Three weeks ago, checking on the boat, I noticed a small amount of antifreeze, maybe a couple of tablespoons, under the Twin Disc transmission. Check around engine. Couldn’t see any obvious source of leak. Wiped area dry. Yesterday, back down to boat and noticed the same situation, a couple of tablespoons of yellow antifreeze directly under and to the rear of the Twin Disc tranny (see photo). I’m using a 50/50 mix of properly rated ethylene glycol A/F which tested to well below -30 degrees. Wiped up puddle. Opened the cap on engine expansion tank, and it was UNDER PRESSURE, pushing out a couple of tablespoons of A/F. Don’t know why pressurize A/F in expansion tank didn’t flow into overflow bottle. The overflow bottle was empty, and the hose to the bottle was clear. Overflow bottle has always handled heated and cooled A/F during normal operation. Checked around and under engine. Still can’t see any source of leak. No drops of A/F under engine block (I’ve got white absorbent mats under engine, nothing). Only close source of A/F would be the 2 hoses leading into and out of the hot water tank, but hoses and clamps appear to be OK. Relief valves on top of heat exchanger and on top of JWAC are shut tight.

I understand that there will be some expansion of A/F with our recent below zero temps. I’ve removed the cap and drained about quarter cup of A/F out of expansion tank. I left the cap on but loose, so now there shouldn’t be any pressure build up. I’ll check it again over next several weeks. I’m assuming without pressure, I won’t see any A/F.

My question… does anyone have an idea where this antifreeze might be coming from? Will not be able to fire up engine until April. Have not seen this issue in the 13 years I´ve had the boat.

Topic

[John]

Update… after removing cap on expansion tank and removing a little antifreeze, no additional leaking. I’ll assume freeze/thaw cycle caused pressure and forced some antifreeze out of hoses somewhere. Once in the water, I’ll watch it. Will check hoses and clamps more often, and release expansion tank cap next Fall as we go into Winter storage.

[William Walter]

Antifreeze leak

Found a little antifreeze in bilge under port engine this week.glad I reread this thread.

[Rob Schepis]

Notice no input from Tony & Corey on the effects of storing a boat in zero degree weather…. maybe if this thread was about “What if my engine gets too much sun ?” Sorry fellas, but this is when us north east folks get a tad jealous of your SoCal weather!

[Wayne Sos]

Same problem fixed

This happened last season and I didn’t discover it until April last year. The coolant wa comment from the fitting on the recovery bottle. And I tightened the clamps. I was down last weekend and some coolant leaked again. I pulled the hose and shined a bright light on the hose. Found some small cracks in the hose. Hose is cheap. Replace them and the clamps. That’s what I’m going to do.

[mark gaudy]

Exactly what Rob and Philip said. Take it from someone who has stored boats in Buffalo NY for 40 years.
Snug up your hose clamps, tighten your pressure cap back down and go home and throw another log on the fire.

[Rob Schepis]

Yup, just gonna take some crawling and exploring with a nutdriver in hand.. When it got down to ~2degF here on Long Island the Wolverines keep the engine room air space at ~20degF and the of course the engines themselves were warmer than that. That was such an extreme cold and it lasted so long, I wonder how many boats with “marginally” winterized fresh water and waste systems will be getting some new components this Spring – I betcha quite a few…

[Philip]

Just a guess, but I bet the cold temps shrunk a hose and the clamp need tightening. The collection point under the transmission is probably just a low point. Get in there with a flashlight and some clean rags. Wipe all the hose/clamp point and see if the rag comes up wet. Then go through all your hose clamps and make sure the are snug.

Phil

[Rob Schepis]

The expansion tank was under pressure because the coolant contracted during that extreme cold period you mentioned, then things warmed up again, like a 50deg delta maybe, causing the coolant to expand but not enough pressure to compress the expansion cap spring and discharge from the expansion tank to the recovery bottle.

Not sure where the stuff in the bilge is coming from since you have a recovery bottle.

[Author]

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