Zinc's on Yanmar 2GMF

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Oct 28, 2005
89
Hunter 31 Portage De Sioux, MO
I have a question regarding zinc's on a Yanmar 2GMF engine. Are there any in the heat exchanger of the 2GMF? I have read some threads that this is a part of the annual inspection. A Yanmar rep. told me there aren't any on this engine. I find that odd. I have never inspected mine since purchasing our 87 Hunter 31 in 2004. It sounds like an inspection I need to start doing. Our sailing area is fresh water.
Some history to offer. One year after purchase I opened the coolant cap and noticed a large, perfectly round dark color ball floating in the anti freeze. I managed to get it out and found it to be very soft. (Like old rubber, or gum.) I called Yanmar and asked a Tech if he had ever seen anything like that before. He said no. I asked him if he though it could be part of the fresh water impellar that has come lose, or an "O" ring that has desolved. No to both questions. His opinion is it may have been some radiator stop-leak. Can't iimagine the PO doing this. So for the last 2 years I have experienced low coolant level in the engine from time to time. And more coolant in the overflow bottle than should be. No visiable leaks on engine, or on the paper I put under the engine to detect a leak.
So I am trying to determine if I have a heat exchanger problem, or a head gasket problem. I just received all repair parts in the mail to do this project, and was looking for some advice from fellow sailors who may have information to offer on this great web site. Thanks for your time gentleman. Fair Winds to all. :confused:
 
Nov 6, 2006
9,884
Hunter 34 Mandeville Louisiana
Nope, no zincs in the raw water side.. Ya have a very little cast iron and bronze, not a very corrosive match.. and since you are in fresh water, even less of a problem..The raw water is on the tube side so all it "sees" is the exchanger end caps and the inside of the tubes.. and the hoses I don't know what the ball could have been ?? but there are no (normal) things in the fresh water side (antifreeze side) that look like that.. There used to be some anti corrode balls that were sold at auto parts places that were meant to go into the radiator..?? maybe someone pout one in the exchanger? It would be good to pull the exchanger and clean the tube bundle and replace the end gaskets .Be vigilant about the position of the tube bundle and the end gaskets. . Get your radiator cap tested .. it sounds like you may have a bad pressure cap.. I hope this fixes it without messing with the head and head gasket.. The raw water impeller should be changed about every other season..
 
Dec 2, 1999
15,184
Hunter Vision-36 Rio Vista, CA.
No zincs on a Fresh water cooled model. I am not sure on the raw water cooled versions.
 

Scott

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Sep 24, 1997
242
Hunter 31_83-87 Middle River, Md
Sound advice from the prior posts. If you don't have an over heating problem, no reason to take apart the heat exchanger. No zincs on the the 2gm20f. It sounds like a bad pressure cap or loss of vacuum in the tube from coolant reservoir back to the engine.
 
Dec 2, 1999
15,184
Hunter Vision-36 Rio Vista, CA.
What type of coolant are you using?

Yanmar recommends the Dex-cool extended life. If you mix them (green & orange) in your system it can be a real mess. The stuff turns to mud. The system needs to be completely flushed if you go this route (including water heater and all lines.)

You may want to open the heat exchanger and see what you find.
 
Oct 28, 2005
89
Hunter 31 Portage De Sioux, MO
Thanks guys for satisfying my curiosity. Had some suspicions and just wanted conformation. Guess the little grease balls will remain a mistry. Steve, I run the green stuff. Will probably clean system and put Yanmar recommended anti freeze as you suggest. Heading to harbor this weekend to open boat up for the season. Hope to get a day or two sailing in before the snow and ice melt up north. Rive floods, then we are tied to the marina. Again, thanks for the input. :)
 
Apr 12, 2011
2
Hunter 30 T Whidbey Island
Another place to look for leaking coolant is the water heater. On my '91 Hunter 30 we could not find the cause of slow loss of coolant. Had the yard look at it. It turns out the hose clamps at the water heater were loose. We've had no more problems since they were tightened up.
 
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