Missing antifreeze!

Tally Ho

Tally Ho

.
Jan 7, 2011
4,789
Oday 322 East Chicago, IN
My new to me O'Day 322 has a Yanmar 2GM20F aux.

While bringing her home late last season across Lake Michigan, the engine alarm went off after motoring for about 1/2 hour in rough seas.

I throttled back some, and while considering options to return back to harbor, the alarm stopped, and I was able to motor at a lower RPM for several hours. Once in port, I found the antifreeze to be very low. I filled it with water, and motored 10 hours the next day at full RPM. I drained the water and filled it with fresh antifreeze at haul out.

While checking on the boat recently (on the hard, not run since I filled up the antifreeze), I found the antifreeze level down again.

Nothing in the bilge, and can't see any leaks.

What should I be checking? Seems odd that the level would be down, with no antifreeze in the bilge and the engine has not been fired up.

Greg
 
woodster

woodster

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Sep 15, 2009
6,243
S2 9.2a Fairhope Al
is your hot water heater plumbed in to the cooling circuit if so i would look there first it may have had an air lock and burped after you left it for the winter .....if you don't see any antifreeze in the bilge water it may be what i described...also check your engine oil for traces of it in the crankcase oil ....you also may want to top it off in the heat exchanger reservoir and fill up the recovery tank to about 1/2 way between low and full and let it sit and see if you still have the problem....
 
kloudie1

kloudie1

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Nov 6, 2006
9,894
Hunter 34 Mandeville Louisiana
Unfortunately, this could also be a pin hole in the heat exchanger tubes or a leaking o-ring tube bundle seal. The antifreeze side is at a higher pressure than the sea water side when running, so any leakage of coolant due to an exchanger tube hole would go out the exhaust .. If burping doesn't stop the loss, you'll have to do some more looking around the cooling system.
 
Claude L.-Auger

Claude L.-Auger

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Dec 14, 2003
1,401
Hunter 34 Lake of Two Mountains, QC, Can
kloudie1 said:
Unfortunately, this could also be a pin hole in the heat exchanger tubes or a leaking o-ring tube bundle seal. The antifreeze side is at a higher pressure than the sea water side when running, so any leakage of coolant due to an exchanger tube hole would go out the exhaust .. If burping doesn't stop the loss, you'll have to do some more looking around the cooling system.
Click to expand
Claude, Greg had mentioned the antifreeze was brought up to full at haul out so engine has not run since and therefore there should not be any pressure difference. Considering the engine cannot be started and run for a while until climate allows it, I would go with Woodster's airlock theory, particularly if it had not been burped after refilling with antifreeze. Greg did not say by how much it was down when he checked recently. Refill again and make sure reservoir is where it should be, leave HX filling cap off and let it sit for some time. If level still good after several days, then wait for Spring, get a pressure tester, start engine and test to see if you get a stable +/- 15 Lbs. If not then a leak in the cooling system is the culprit.

Greg, you said you ran 10 hours at full RPM ? While our engines can and should be run at full RPM now and then, I've never heard of anyone doing it for 10 hours. Antifreeze allows the engine to run warmer so 10 hours under full RPM with just water in the system should have led to an overheat situation. Did you say full RPM meaning cruising RPM (I think it's +/- 2800 on Yanmar 2GM) ?
 
kloudie1

kloudie1

.
Nov 6, 2006
9,894
Hunter 34 Mandeville Louisiana
Darn it.. I missed the part where he said that he'd not run it since filling.. I am wrong on my note, Greg.. sorry. If no antifreeze in the bilge or the drinking water, then a bubble/air lock that gradually bled down from the tiny air hole in the thermostat or from the daily temperature cycles.. Good catch, Claude A.
 
Marc14857

Marc14857

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Jun 5, 2004
485
Hunter 44 Mystic, Ct
Missing Antifreeze

I have had this problem on occasion when the boat is stored for the winter. I found the missing antifreeze at the bottom of the engine cubicle not in the bilge. As discussed on this forum, some think that the issue is with the mechanical,seal,on the engine coolant pump. When it gets vey cold the seal or the seating area shrinks just enough for antifreeze to leak past the seal.

I'm not sure that is what is happening in your case but seems to make sense to me.
 
Tally Ho

Tally Ho

.
Jan 7, 2011
4,789
Oday 322 East Chicago, IN
woodster said:
is your hot water heater plumbed in to the cooling circuit if so i would look there first it may have had an air lock and burped after you left it for the winter .....if you don't see any antifreeze in the bilge water it may be what i described...also check your engine oil for traces of it in the crankcase oil ....you also may want to top it off in the heat exchanger reservoir and fill up the recovery tank to about 1/2 way between low and full and let it sit and see if you still have the problem....
Click to expand
I do have my water heater plumbed into the cooling circuit...so maybe that is it. The fact that the level was low the day I was delivering it concerned me, but admittedly, I did not check it before I left port for the long motor home. It has made me a bit nervous ever since, and when I noticed it was low after topping it off at haul out, I was very perplexed.

Thanks for the suggestion.

Greg
 
Tally Ho

Tally Ho

.
Jan 7, 2011
4,789
Oday 322 East Chicago, IN
kloudie1 said:
Unfortunately, this could also be a pin hole in the heat exchanger tubes or a leaking o-ring tube bundle seal. The antifreeze side is at a higher pressure than the sea water side when running, so any leakage of coolant due to an exchanger tube hole would go out the exhaust .. If burping doesn't stop the loss, you'll have to do some more looking around the cooling system.
Click to expand
this is what had me worried, or that I had a bad head gasket or something (do diesels have head gaskets ?).

Anyway, I saw your further note, so I will keep,this in reserve if I continue to loose antifreeze once we have her back in the water and the aux in operation.

Thanks,

Greg
 
Tally Ho

Tally Ho

.
Jan 7, 2011
4,789
Oday 322 East Chicago, IN
Claude L.-Auger said:
Claude, Greg had mentioned the antifreeze was brought up to full at haul out so engine has not run since and therefore there should not be any pressure difference. Considering the engine cannot be started and run for a while until climate allows it, I would go with Woodster's airlock theory, particularly if it had not been burped after refilling with antifreeze. Greg did not say by how much it was down when he checked recently. Refill again and make sure reservoir is where it should be, leave HX filling cap off and let it sit for some time. If level still good after several days, then wait for Spring, get a pressure tester, start engine and test to see if you get a stable +/- 15 Lbs. If not then a leak in the cooling system is the culprit.
Click to expand
The tank was down an inch or so when I last checked it. Hopefully it is an airlock issue (I hope so). I will top off it off next time out, and will monitor it until we splash. Then will see if we have further loss.


Greg, you said you ran 10 hours at full RPM ? While our engines can and should be run at full RPM now and then, I've never heard of anyone doing it for 10 hours. Antifreeze allows the engine to run warmer so 10 hours under full RPM with just water in the system should have led to an overheat situation. Did you say full RPM meaning cruising RPM (I think it's +/- 2800 on Yanmar 2GM) ?
Click to expand
I am not sure if there was any antifreeze in the system or not, just that the tank was very low (I could not see any antifreeze in the tank). We filled it with water to make the rest of the trip home, so not sure if it was pure water or a mix of diluted antifreeze.

We ran her about 3200RPM's (My normal cruising RPM).

She ran fine with the water in the cooling system, but the alarm went off on the first day, heading directly into a stiff headwind and bashing through some big waves off the bow. Admittedly I was pushing the RPMs a bit harder that first day. After dropping the revs under 3000, the alarm stopped and I made it to the next port, filled her with water and made the 10 hour trip the next morning (calmer seas but still had headwinds).

Thanks for the good suggestions.

Greg
 
Tally Ho

Tally Ho

.
Jan 7, 2011
4,789
Oday 322 East Chicago, IN
Marc14857 said:
I have had this problem on occasion when the boat is stored for the winter. I found the missing antifreeze at the bottom of the engine cubicle not in the bilge. As discussed on this forum, some think that the issue is with the mechanical,seal,on the engine coolant pump. When it gets vey cold the seal or the seating area shrinks just enough for antifreeze to leak past the seal. I'm not sure that is what is happening in your case but seems to make sense to me.
Click to expand
I do have a pan under the engine, above the bilge....I think it is dry, but I will double check.

I am still hoping for an airlock, and once burped, she will be fine. But your suggestion is something I will double check.

Thanks,

Greg
 
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