# coolant for yanmar diesel?



## NewportNewbie (Jul 30, 2011)

Being this is my first diesel engine I want to be sure. I need to add coolant. It's green coolant. Is that normal automotive coolant? I would imagine yes. My buddy who has a yanmar diesel brought some pink coolant and said his uses that. Can I mix green and pink? I know with my BMW I can't mix green and blue. It's one it the other. Thx!


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## NewportNewbie (Jul 30, 2011)

Found the info. Pink and green don't mix and yanmar has stated the green coolant can break down the cylinder walls. Red coolant is what's supposed to be used.


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## Minnewaska (Feb 21, 2010)

Ever since a mechanic showed me some gelatinized coolant from a motor that had mixed coolant types, I've been paranoid. I don't know which combo will do that, which makes me more paranoid.

Drain it and start from scratch. Coolant should be replaced periodically anyway. Manuals usually say annually.


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## arf145 (Jul 25, 2007)

My 2GM20F came with green in it. Don't know how long it was like that. When I finally got around to replacing, I drained what was in there and used Prestone Extended Life, which is green. If this is bad, then I guess it has been bad for a while. 

Still I think this isn't just a matter of antifreeze color--even the pinks aren't all the same. Wouldn't mind hearing the definitive word on this.


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## arf145 (Jul 25, 2007)

So no Yanmar mechanic or other expert is going to weigh in on this?


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## Tim R. (Mar 23, 2003)

I can tell you after speaking to a Yanmar mechanic and reading the manuals, anything other than what Yanmar specifically recommends voids the warranty.


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## arf145 (Jul 25, 2007)

I'm not too worried about the warranty on my 25-yr-old engine. And I wonder if the recommendations in my 25-yr-old manual might have changed just because of changes in the products/technology out there. Does Yanmar publish current recommendations for older engines?


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## dbw_kairos (May 25, 2015)

I have a yanmar 2GM20F - my first diesel engine (my first boat actually). I need to add coolant. I know that I need to change the coolant completely and choose either red or green. 

But my question is this: if at this time I only want to add coolant, can I do that? Or do I have to drain everything? If I can just add some to get me through the summer before I drain it all at the winter, what kind can I add? (currently there is green). Or can I just add water? 

I only motor about 15 minutes at a time (15 to get out of marina and 15 to get in) and I only sail about 2-3 times a week. Is it ok to wait to drain and put in all new coolant this winter and simply add some for the time being? 

Thanks !


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## aa3jy (Jul 23, 2006)

Shell Dex Cool Extended Life 50/50


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## Skipper Jer (Aug 26, 2008)

Yanmar has their own brand of coolant: YANMAR Ultralife YG30.
In the advisory ( http://portal.mastry.com/bulletins/Misc Advisories/Anti Freeze.pdf) they go on to say Mr. Goodwrench Texaco and Shell meet the requirements.
Another bulletin ( http://ldmarineservice.com/files/yanmar_bulletins.pdf ) approved Texaco Long Life Coolant, Havoline Extended Life, Dex-Cool and Prestone Extended Life.


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## CS Cruiser (Dec 5, 2011)

Must meet manufacturers specs, but as far as color goes its that you don't want to mix ethylene glycol with propylene glycol regardless of color.


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## Skipper Jer (Aug 26, 2008)

CS Cruiser said:


> Must meet manufacturers specs, but as far as color goes its that you don't want to mix ethylene glycol with propylene glycol regardless of color.


Yes, I would think the proper thing to do is if you are not sure what is in there is to drain the system, maybe do a fresh water flush, then fill with the approved coolant.


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## RainDog (Jun 9, 2009)

I recently went through this, and after researching for quite some time was just more confused. This was one of the single most confusing boat topics I have ever looked into. In the end the best thing I found was:

Steven Cyr's Stella Blue Site

And I used: NAPA AUTO PARTS.

Before adding the new coolant I drained and flushed with distilled water about 4 times until the water ran (almost) clear. Some recommend an acid bath for the system, but with a 25 year old engine, I was afraid the deposits might be the only thing holding everything together, so skipped it.

I did all the work myself, and the only problem I has was the the engine caught fire next time I ran it.


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## hollendu (Dec 5, 2003)

Has anyone used Prestone Low Tox or Peak Sierra propylene glycol antifreeze? They both meet Yanmar's ASTM D3306 nad D4985 specs. They are more friendly to the environment.


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## XSrcing (Aug 22, 2015)

As long as you service your system every 5 years you can run the green stuff no problem. If you are lazy with boat maintenance, then use red. If you are the kind of person who forgets you have coolant, use the purple stuff.


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## pdqaltair (Nov 14, 2008)

arf145 said:


> Still I think this isn't just a matter of antifreeze color--even the pinks aren't all the same. Wouldn't mind hearing the definitive word on this.


I'm in the business and on the ASTM committee. There is no color standard not is there every likely to be one. Too many marketing dollars. Going by color is pointless.

That said, the new nitrite-free HD coolants have very broad compatibility.


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## pdqaltair (Nov 14, 2008)

hollendu said:


> Has anyone used Prestone Low Tox or Peak Sierra propylene glycol antifreeze? They both meet Yanmar's ASTM D3306 nad D4985 specs. They are more friendly to the environment.


They are NOT more friendly to the environment. Toxicity to fish is low for both types of glycol, and they are both equally biodegradeable. Additionally, PG has many material compatibility issues (bad for many plastics). A grave risk unless the engines and hoses were speced for PG.

http://water.epa.gov/scitech/wastetech/guide/airport/upload/2005_10_07_guide_airport_airport.pdf

_9.1.1
Aquatic Toxicity
Both ethylene glycol and propylene glycol exhibit similar aquatic toxicity
characteristics. Acute and chronic tests have been performed for both glycols. Data were
Section 9.0 - Toxicity of Deicing/Anti-Icing Agents
9-3
acquired from several sources, particularly individual studies that performed similar tests on both
ethylene glycol and propylene glycol. Tests were performed on both freshwater and marine
aquatic life. Acute tests were performed to determine the lethal concentration for 50% of the
sample population (LC
) over a short period of time (48 to 96 hours). Chronic tests were
50
performed over a longer period of time (7 to 14 days)....

In general, the data show that ethylene glycol and propylene glycol exhibit aquatic toxicological
effects at concentrations within the same order of magnitude. Although EPA does not use such a
system, the U.S. Fish and Wildlife Service Classification System for Acute Exposures defines
"relatively harmless" as any chemical with an LC
above 1,000 mg/L (3). The test results shown
50
in Table 9-1 indicate that ethylene glycol and propylene glycol may be classified as "relatively
harmless," as defined by the U.S. Fish and Wildlife Service._

---

The notion that PG is better for the environment is urban legend perpetuated by the manufacturers and well-meaning consumers that have not done the research. Both should be recovered and recycled if practical.


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## RobGallagher (Aug 22, 2001)

pdqaltair said:


> I'm in the business and on the ASTM committee. There is no color standard not is there every likely to be one. Too many marketing dollars. Going by color is pointless.
> 
> That said, the new nitrite-free HD coolants have very broad compatibility.


If you had no idea what was in your system (other than it appeared to be antifreeze). What would you say is best for a late 1980's 2GM20F (should I still go by the Yanmar manual or is it outdated on these products).

Do you recommend flushing with water before putting in the new coolant?

Thanks!


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