I know it has been asked and answered in the past, but I didn't make note of it then. What is the currently recommended COOLANT to be added to the fresh Water Cooling System of the Yanmar 2GM20F engine?
Recommended fresh Water COOLANT for 2GM20F
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We are using the Shell brand of the Dexcool in our 3JH2E. Yanmar recommends this for all of their engines now.
Be VERY careful if you are changing from the old (green) stuff. If you mix the old and new it can turn to a gel/goo. You must completely flush the entire system (water heater and all hoses too) before you refresh with the new product.
Be VERY careful if you are changing from the old (green) stuff. If you mix the old and new it can turn to a gel/goo. You must completely flush the entire system (water heater and all hoses too) before you refresh with the new product.
Too many horror stories about DexCool .. I use the plain old green long-life stuff.. Read this through.. http://en.wikipedia.org/wiki/Antifreeze
Dex is proplyene glycol (note : not correct.. ;note following posts.. ) and its main plus is that it is not (as) toxic as the old stuff but note in the discriptions the part about forming lactic acid.. In function, if you forget to change the old stuff, it loses its anti-corrosive additives.. if you forget to change Dex, it does the same thing which is then followed by the generation of heavy scaling which may plug the system.. It is fine to use, but be very careful about changing it..
Dex is proplyene glycol (note : not correct.. ;note following posts.. ) and its main plus is that it is not (as) toxic as the old stuff but note in the discriptions the part about forming lactic acid.. In function, if you forget to change the old stuff, it loses its anti-corrosive additives.. if you forget to change Dex, it does the same thing which is then followed by the generation of heavy scaling which may plug the system.. It is fine to use, but be very careful about changing it..
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Dex-cool engine coolant is ethylene glycol-based, and the problems originally thought to be caused by/associated with it have long since been resolved.
Cheers,
Brad
Research before posting; Dexcool is EG based.
A discussion of the compatibility of Dexcool with elastomers and other coolants is beyond a simple forum; arguments raged between vendors and OEMs for years. However, the conventional wisdom is that switching to Dexcool from other coolants is problematical (corrosion) and that plugging can be a problem if the engines is not clean (the primary additive, a soap, tends to clump up dirt). It was a pioneering product with a few quirks.
If you have a Dexcool system, keep it clean and don't mix other coolants. If you switch to another coolant, flush well and chose a hybrid type.
(I work in the industry, formulate coolants, have tested MANY samples, and run many test engines. However, I have no association with Dexcool.)
http://www.valvoline.com/pdf/zerexdexcool.pdf
A discussion of the compatibility of Dexcool with elastomers and other coolants is beyond a simple forum; arguments raged between vendors and OEMs for years. However, the conventional wisdom is that switching to Dexcool from other coolants is problematical (corrosion) and that plugging can be a problem if the engines is not clean (the primary additive, a soap, tends to clump up dirt). It was a pioneering product with a few quirks.
If you have a Dexcool system, keep it clean and don't mix other coolants. If you switch to another coolant, flush well and chose a hybrid type.
(I work in the industry, formulate coolants, have tested MANY samples, and run many test engines. However, I have no association with Dexcool.)
OK "Thinwater" I get your point. If not Dex-Cool, what do you use or recommend for small diesel engines like Yanmar 2GM20F, etc.?
I stand corrected.. Not Propylene Glycol but does have the OAT package.. Again this is my take after having to replace one plugged radiator (2 years ago, never operated with low coolant levels and never cross contaminated) and finding the other car with the beginnings of the same problem.. again never operated with low coolant levels, and never contaminated with any other coolant. Both are now on the green stuff that I have pretty much used without such incidents for the past 44 years..
Texaco ELC is what Yanmar's ship with as last I knew.
Here's a Yanmar TSB on what coolants:
Yanmar Approved Coolants
and the tech sheet for Texaco ELC
Texaco ELC
Here's a Yanmar TSB on what coolants:
Yanmar Approved Coolants
and the tech sheet for Texaco ELC
Texaco ELC
I wouldn't be afraid of Dexcool
There's a lot of internet discussion and a few horror stories, but they are easy to avoid. It is fundamentally an excellent product with long life and excellent corrosion protection.
The other thing about organic acid technology (OAT) coolants (all long-life coolants, including Dexcool) is that they offer significantly better protection against diesel engine cavitation pitting than light duty conventional coolants like old green Prestone (which now sell only under the "Prime" name). I don't know if Yanmars have any susceptibility to this malady; larger wet sleeve engines do. For those, Old World's Final Charge, Penray 2798N, and Prestone HD Extended Life are solid choices.
There's a lot of internet discussion and a few horror stories, but they are easy to avoid. It is fundamentally an excellent product with long life and excellent corrosion protection.
The other thing about organic acid technology (OAT) coolants (all long-life coolants, including Dexcool) is that they offer significantly better protection against diesel engine cavitation pitting than light duty conventional coolants like old green Prestone (which now sell only under the "Prime" name). I don't know if Yanmars have any susceptibility to this malady; larger wet sleeve engines do. For those, Old World's Final Charge, Penray 2798N, and Prestone HD Extended Life are solid choices.
Yanmar Antifreeze
I had the DexCool issues with my 2002 Pontiac Gran Prix which cost me almost $1,000 to have the intake manifold gasket and water pump replaced. I cleaned out the DexCool and switched to 'Green'. Mixing the two do cause a granular mucky brown mix that can at least clog the radiator cap. If you Google DexCool you will get quite a few horror stories on the automotive side.. I know I won't use it again.
Following that experience and needing to change the coolant in the 2GM20F, I asked Yanmar about DexCool and they said they had no compllaints with DexCool, but recommended their own 'brand' of antifreeze. The stuff is pre-mixed 50-50 and is also orange but seems to be doing fine in my 2GM20F. I did use Prestone's flushing / cleaning kit and three complete flushes with fresh water before installing the Yanmar orange antifreeze.
I had the DexCool issues with my 2002 Pontiac Gran Prix which cost me almost $1,000 to have the intake manifold gasket and water pump replaced. I cleaned out the DexCool and switched to 'Green'. Mixing the two do cause a granular mucky brown mix that can at least clog the radiator cap. If you Google DexCool you will get quite a few horror stories on the automotive side.. I know I won't use it again.
Following that experience and needing to change the coolant in the 2GM20F, I asked Yanmar about DexCool and they said they had no compllaints with DexCool, but recommended their own 'brand' of antifreeze. The stuff is pre-mixed 50-50 and is also orange but seems to be doing fine in my 2GM20F. I did use Prestone's flushing / cleaning kit and three complete flushes with fresh water before installing the Yanmar orange antifreeze.
Re: Yanmar Antifreeze
One of the first, and a potentially serious issue that I encountered with my boat four years ago after the first outing was noticing that the coolant was jet black. That was even after I had drained (once) and refilled prior to the first sail. Responses to a post to this forum first suggested maybe a blown head gasket was allowing carbon blow-by into the coolant. But another one or two respondents raised the possibility of a Dex-Cool issue. I really don't know what the PO had used, but after many drains and flush-outs and finally a refill with a well known brand of extended 5-year life green stuff, I finally got the coolant to stay clean without black. Even though this anti-freeze is rated 5-year, I have changed several times. Its green and clear each time. Guess I didn't have a blown head gasket.
My Yanmar 2QM20 was a seawater cooled design, but modified to a self-contained antifreeze system with the addition of a bulkhead mounted heat exchanger and an extra pump. As above, the antifreeze I am using is not on Yanmar's recommended list -- but its still got to be a whole lot better than salt seawater coursing through my engine! Also, my older engine, and probably your GM series, does not have any aluminum components that I've observed. Aluminum corrosion seems to be a factor in Yanmar's current coolant recommendations, per Mainsail's link to the url.
As others have posted, if you don't know what currently in your engine, its probably a good idea flush thoroughly, and then again, and then even again for good measure before doing the new anti-freeze. Then after a season, drain and fill again. Overkill, most likely. But in my younger years with cars I had several instances of heater cores going bad due to not replacing the coolant frequently enough. I am actually more diligent on my boat engine with the coolant than I am about the oil. (Although I don't neglect this either.)
One of the first, and a potentially serious issue that I encountered with my boat four years ago after the first outing was noticing that the coolant was jet black. That was even after I had drained (once) and refilled prior to the first sail. Responses to a post to this forum first suggested maybe a blown head gasket was allowing carbon blow-by into the coolant. But another one or two respondents raised the possibility of a Dex-Cool issue. I really don't know what the PO had used, but after many drains and flush-outs and finally a refill with a well known brand of extended 5-year life green stuff, I finally got the coolant to stay clean without black. Even though this anti-freeze is rated 5-year, I have changed several times. Its green and clear each time. Guess I didn't have a blown head gasket.
My Yanmar 2QM20 was a seawater cooled design, but modified to a self-contained antifreeze system with the addition of a bulkhead mounted heat exchanger and an extra pump. As above, the antifreeze I am using is not on Yanmar's recommended list -- but its still got to be a whole lot better than salt seawater coursing through my engine! Also, my older engine, and probably your GM series, does not have any aluminum components that I've observed. Aluminum corrosion seems to be a factor in Yanmar's current coolant recommendations, per Mainsail's link to the url.
As others have posted, if you don't know what currently in your engine, its probably a good idea flush thoroughly, and then again, and then even again for good measure before doing the new anti-freeze. Then after a season, drain and fill again. Overkill, most likely. But in my younger years with cars I had several instances of heater cores going bad due to not replacing the coolant frequently enough. I am actually more diligent on my boat engine with the coolant than I am about the oil. (Although I don't neglect this either.)
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