Losing antifreeze

Tally Ho

Tally Ho

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Jan 7, 2011
5,621
Oday 322 East Chicago, IN
i have a Yanmar 2GM20F inboard. Have owned the boat for 2 years, and have been losing antifreeze since I bought her. On my maiden voyage to bring her across Lake Michigan, the engine alarm went off while powering through some big waves and fighting a head wind. Throttled back and the alarm stopped and I limped her into a port for the night. Inspection found the antifreeze level in the tank was very low. Topped it off and motored for 14 hours the next day without incident.

However, upon periodic inspection, the antifreeze level would be down. I never noticed antifreeze in the engine pan, and suspected a leak in the heat exchanger tubes that maybe was allowing the antifreeze to exit with the freshwater exhaust. I topped it off periodically during the summer and topped it off while winterizing the boat.

Went out recently to check on her and saw antifreeze in the engine pan, and the tank was low again.

I don't see any obvious wet spots or locations it could be leaking.

Anyone have any ideas about potential leak points on the 2GM20F that I can focus on?

Greg
 
weinie

weinie

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Sep 6, 2010
1,297
Jeanneau 349 port washington, ny
Suspect blown head gasket. What does your oil look like. Is the level rising?
 
kloudie1

kloudie1

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Nov 6, 2006
10,095
Hunter 34 Mandeville Louisiana
Is the hose between the radiator cap and the plastic expansion tank leaking?
Radiator cap leaking?
 
Tally Ho

Tally Ho

.
Jan 7, 2011
5,621
Oday 322 East Chicago, IN
weinie said:
Suspect blown head gasket. What does your oil look like. Is the level rising?
Click to expand
Oil is normal (black), but have had it tested. Level remains consistent through the the season. I originally suspected something like a head gasket since I did not see antifreeze anywhere. Now that I see a puddle in the engine pan, I am suspecting some other sort of leak.

Greg
 
Tally Ho

Tally Ho

.
Jan 7, 2011
5,621
Oday 322 East Chicago, IN
kloudie1 said:
Is the hose between the radiator cap and the plastic expansion tank leaking?
Radiator cap leaking?
Click to expand
I replaced the cap last year as it looked pretty dicey (rusty). Neck of the tank seems smooth and clean, so I don't think it is the cap. Especially since it leaked with no pressure over the layup. The expansion tank never has anything in it, but import think the hose is the issue since it leaked over the winter and the system was not pressurized at all.

Good suggestions though....keep 'em coming!

Greg
 
Tally Ho

Tally Ho

.
Jan 7, 2011
5,621
Oday 322 East Chicago, IN
Sailm8 said:
Any chance there is a crack in the return/overflow tank?
Click to expand
If you mean the plastic expansion tank, I don't think so. And there is no antifreeze in there (at least not over the winter when these is no pressure in the system).

Greg
 
kappykaplan

kappykaplan

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May 1, 2011
5,026
Pearson 37 Lusby MD
What about the thermostat housing? Mine cracked last year (Universal) and put lots of antifreeze in the engine pan - not an inexpensive fix.
 
Stu Jackson

Stu Jackson

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Feb 26, 2004
23,049
Catalina 34 224 Maple Bay, BC, Canada
Greg, why not approach it systematically? Step-by-step. Not yet menitoned: a loose hose connection or old hoses.

Analyze the entire system.
 
Tom J

Tom J

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Sep 30, 2008
2,325
Catalina 310 Quincy, MA
Why is there nothing in the expansion tank? The tank should be 1/4 to 1/3 full of antifreeze when the engine is cold, and more when the engine is warm. If the tank is empty when the engine is cold, then air is being pulled into the system when the engine cools down, which would seem to defeat the purpose of the expansion tank.
I had a similar problem on my engine, and found the plastic fitting on the tank was not smooth, and was allowing fluid to leak from the hose connection.
 
Tally Ho

Tally Ho

.
Jan 7, 2011
5,621
Oday 322 East Chicago, IN
I am not
kappykaplan said:
What about the thermostat housing? Mine cracked last year (Universal) and put lots of antifreeze in the engine pan - not an inexpensive fix.
Click to expand
sure where that is on my Yanmar, but I will look at the drawings.

Thanks for the tip.

Wish me luck!

Greg
 
Tally Ho

Tally Ho

.
Jan 7, 2011
5,621
Oday 322 East Chicago, IN
Stu Jackson said:
Greg, why not approach it systematically? Step-by-step. Not yet menitoned: a loose hose connection or old hoses.

Analyze the entire system.
Click to expand
Thanks Stu,

I guess I don't really know where to start or what steps to check...hence my post.

I originally thought it was something internal...head gasket or leak in the heat exchanger since I was not seeing any antifreeze anywhere. Or maybe it was in the line that runs to the water heater (but I never found a leak there either). Now that I see it in the engine pan, I am assuming it is leaking out of the system somewhere external to the engine. The fact that it is leaking while the engine is not running should be a clue I would think.

Hoses would be a logical step I guess, but I assumed the antifreeze system (freshwater) was all internal to the engine (other than the water heater). I will start tracing any hoses to see anything seems wet, loose or cracked.

Thanks.

Greg
 
Tally Ho

Tally Ho

.
Jan 7, 2011
5,621
Oday 322 East Chicago, IN
Tom J said:
Why is there nothing in the expansion tank? The tank should be 1/4 to 1/3 full of antifreeze when the engine is cold, and more when the engine is warm. If the tank is empty when the engine is cold, then air is being pulled into the system when the engine cools down, which would seem to defeat the purpose of the expansion tank.
I had a similar problem on my engine, and found the plastic fitting on the tank was not smooth, and was allowing fluid to leak from the hose connection.
Click to expand
. I have never seen anything in the expansion tank, and assumed it was there really to catch any overflow if the system was over-pressure.

Is the tank supposed to be mounted above or below the cap? Or does it not matter? My engine compartment head room will not really let me mount it higher than the cap.

I will certainly check the fitting and hose, maybe that is why there isn't anything in the tank...but that is not the source of my leak.

Thanks,

Greg
 
Tom J

Tom J

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Sep 30, 2008
2,325
Catalina 310 Quincy, MA
Greg, the tank does not have to be higher than the cap. When the system reaches max pressure, coolant will flow to the tank because the pressure cap has opened. As the system cools, the coolants will flow back into the engine through the cap, until the cap closes again. Keeping enough coolant in the tank keeps air from being sucked back into the system, improving the performance of the cooling system. The tank is also an indicator of coolant level. Often, the tank will have to be refilled several times if it had been empty. A little air is expelled each time the engine is run, and at some point, the level in the tank should return to its normal level after each engine run.
I agree you probably have a small leak somewhere else in the system. I have at times found coolant in the engine pan, and found a loose clamp on one or another of the hose clamps.
 
FastOlson

FastOlson

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Apr 8, 2010
2,121
Ericson Yachts Olson 34 28400 Portland OR
First, checkout the heat exchanger for a small leak from the coolant side to the raw water side. What will all those little tubes in there, it's not unheard of for a leak to happen. Also, does your H.E. have a zinc? Has it been changed out regularly? It's also possible for that zinc to be eaten away and then the metal to erode and a pin hole develop.
Good luck on the trouble shooting.
Loren
 
woodster

woodster

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Sep 15, 2009
6,243
S2 9.2a Fairhope Al
fyi the 2gm20f does not have a zinc..... but as stu said start with the hose connections first...... this is simple detective work one step at a time....... then also check the drain petcocks on the side of the block to make sure they are holding....... this is a complex system and has to be be checked one step at a time ...it may help to study a diagram of the system in order to be able to understand what is going on
 
Tally Ho

Tally Ho

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Jan 7, 2011
5,621
Oday 322 East Chicago, IN
Thanks Tom. I will work on the expansion tank.

Just noticed you are in Maui. Do you keep a boat in Lahaina?

Sailed on a 50' Santa Cruz out there last month. Just had to watch out for all of the whales!

Greg
 
Tally Ho

Tally Ho

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Jan 7, 2011
5,621
Oday 322 East Chicago, IN
Fast / Woodster -

Thanks for the suggestions. I think I can find a copy of the Yanmar engine manual.

Looks like it just take time to find a slow leak.....

Thanks all for the suggestions and education.

Greg
 
P

Philip_Oceanis 361

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Nov 23, 2009
437
Beneteau Oceanis 361 Clipper --
Some time ago I was messing around with the heat exchanger of my Volvo MD2030 and I pushed the heat exchanger tube out of its correct place (there are two "rubber covers" holding it). The result was coolant finding its way in the exchaust hose with the sea water. It was only a matter of placing the tube in the correct position. No problem since then.
 
whatfiero

whatfiero

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Oct 30, 2011
542
klidescope 30t norfolk
Local auto parts stores rent let you borrow a pressure test tool and it comes with several Capps just like the one on your heat exchanger pressure capp normally goes on the radiator you pump it up and look- listen for leek
 
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