[eherlihy]

TL;DR

This is what I run in my Universal M25's closed loop cooling system;

Despite the statement that it is good for 150K miles, I change it every three years. It is blue BTW.

I drain the raw water side of my engine's cooling system by;

• opening the through hull, then using a shop vac sucking everything out of the raw water strainer,
• then I pull the impeller and shop vac the line from the strainer to the pump,
• then I remove the sacrificial anode from the H/X and vacuum the H/X and the line from the pump dry,
• then I remove the drain on the waterlift muffler and use the shop vac to suck all the water out of the muffler and the line to the transom through hull.

I drain my (potable?) freshwater system including the hot water heater, and blow each and every one of the lines clear with my compressor, then I add 1.5 gallons of this to the fresh water system;

I then open each valve individually to make sure that pink liquid comes out. Each valve means:

• hot water heater
• galley hot
• galley cold
• head hot
• head cold
• handheld shower
• Vacuflush head

I pour the last 0.5 gallon into the holding tank through the pump out fitting.

I then open and close each of the overboard discharge seacocks (galley sink and holding tank) to make sure that these lines are clear and to exercise the valves.

 

[Minnewaska]

This may be an old wives tale, but I’ve always been OCD to not mix different kinds of coolant on the fresh water side (ie. Engine coolant). I’ve been told the wrong mix could congeal. As a result, I generally just buy OEM coolant/antifreeze, to be sure it’s compatible.

This has nothing to do with winterizing the raw water side of an engine, just a random thought.

 

[pdqaltair]

Two chemicals are used to lower the freezing point of water in "permanent" antifreeze - ethylene glycol and propylene glycol. Ethylene glycol is used in the green antifreezes. It is both sweet and quite toxic. Ethylene glycol has a serious problem when used as an antifreeze, which is that it gradually forms a gum that coats or plugs the cooling passages, so ethylene glycol antifreeze needs to be flushed and replaced every few years. Ethylene glycol antifreeze is obsolete. For example, Yanmar does not approve using it, and using it could void a warrantee. You may have noticed that the antifreeze for modern cars is pink. Pink is an international standard color for substances that are not very toxic. Pink antifreeze is made with propylene glycol. You may have noticed newer pink antifreezes advertised as good for 150,000 miles. These are modern propylene glycol antifreezes. The antifreeze used to winterize RVs and boats is also pink, because it is nontoxic; it is also made with propylene glycol. Propylene glycol is a permitted food additive; for example, it is added to shredded coconut to keep it moist. As other posters have indicated, winterizing antifreeze should not be used in closed loop cooling systems, because it lacks the corrosion inhibitors, water pump lubricants, and other additives that engines need. One sure way to select your closed-loop antifreeze is to check what your engine manufacturer recommends. When I did this for Yanmar, I encountered four tested and approved brands, all based on propylene glycol.

^^ Nearly all of this is incorrect. Not even close.

* Ethylene glycol is the more effective coolant and antifreeze agent and is used by nearly all vehicle OEMs.
* Orange/pink does not mean PG. Dexcool, perhaps the most common coolant, is orange. There is no national or international color standard.
* The new AFs are not PG. They can be, but the base has little effect on the product, one way of the other. I'm not sure any PG long-life is truly proven at that interval.
* Yanmar engine coolant is EG. https://www.yanmarmarine.com/theme/...verig/Safety_Sheets_oil_coolant/SDS-Yanmar-Genuine-Engine-Coolant-Long-Life.pdf. Dexcool and Prestone XLF are also EG.

And BTW, there is not such thing as "long-life" in marine applications. The risk of salt contamination restricts lifespan recommendations to 2-3 years. Or you can test for salt, with about 50 ppm being condemning.

I could go on. No point.

(I was in the industry for many years, did a lot of testing, and designed two commercial-scale refineries).

 

[rschudy]

Thank you very much for your insights, experience, and corrections.

I came to this forum because I need to change the coolant in my Yanmar, and am struggling to determine what coolant to use. There is an abundance of misinformation on the web and I am trying to understand this without becoming a marine coolant expert. I pasted below a Yanmar service bulletin, reprinted from Mac Boring. I think that the engine manufacturers are also unsure, because not enough time has passed since the new coolant formulations.

Thanks again. I hope that we can reach some kind of shared understanding, if not a consensus.
-Bob Schudy

TO: MARINE DISTRIBUTERS
COOLANT ADDITIVES
After testing some popular coolant/anti-freeze solutions, we have reached the following recommendations. It was not possible to test all brands on the market, so there may be some solutions that are acceptable but have not been tested. However, caution is advised if using other than approved brands. Regardless of the recommendation of the coolant/antifreeze manufacturers it is YANMAR'S requirement that the solution is changed every 500 hours (On the YANMAR Model 6LP 250 hours) or once a year whichever comes first. We do not recommend any other additives be added to the cooling system. Purified or distilled water mixed with the approved coolant/anti-freeze is the only protection approved by YANMAR.
Concentrations of the mixture should follow the recommendations of the manufacturer. The coolant/anti-freeze must be compatible with aluminum.

Advantages of this type of coolant:
• Improved water pump life due to reduced water pump seal wear resulting from fewer abrasive dissolved solids.
• Reduces hard water scale.
• Offers excellent protection against pitting corrosion caused by cylinder liner cavitation. Better heat transfer than conventional coolants with regular SCALE additions.
• No silicate gel formation during use or storage.
• Outstanding hot surface aluminum protection.
• Superior protection in high operating temperature conditions.
• Effective, long-term corrosion protection for aluminum, brass, cast iron, steel, solder and copper alloys.

The coolant/anti-freezes that have been tested and approved are shown below:
• Texaco Long Life Coolant Anti-Freeze both regular and pre-mixed Product codes 7991 and 7998. This product is available in gallon containers, drums and bulk. It is recommended that the cooling system be drained and flushed before filling. Only Texaco Long Life Coolant should be used for top-off. This product has a much longer shelf life than conventional coolants provided
the integrity of the container is maintained. For additional information and availability contact Texaco at 1-800-782-7852.
• Havoline Extended Life Anti-Freeze/Coolant. Product code 7994. This product is available through Texaco gas stations, Procedures are the same as with Texaco Long Life Coolant Anti-Freeze.
• Dex-Cool Long Life Coolant. This product is available through GM service centers worldwide.
• Prestone Extended Life Coolant. Product code AF888. If the above coolants are not readily available, Prestone Extended life coolant is satisfactory.


Prestone AF888 is Dex-Cool formulation.
Havoline 7994 is ethylene glycol formulation.
i haven't found information on Texaco 7991, which is apparently hard to find.
All four are long-life.

 

[rschudy]

I did some more web research and learned that antifreezes and coolants are getting complicated.:

Some long-life coolants now use organic acids as antifreeze.
Some combinations of coolant brands can apparently gel.
There have been successful class action suits against GM for DexCool.
Gunk can be caused by organisms growing in the coolant.
Different corrosion inhibitors are used in the US, Europe, and Japan.
At least green, pink, orange, yellow and blue colorants are used.

I will buy one of the Yanmar-approved coolants and change it as recommended. Since what is in there is probably ethylene glycol based, I will avoid a coolant based on organic acids, which may react with traces left after I flush it.

Many thanks,
Bob

 

[Minnewaska]

....or once a year whichever comes first......

Changing coolant annually sounds brutal. I change ours every 3 or 4 years. It's an easy job, but I always stress that I'll cause a vapor lock and not know it until off the dock.

I think I've mentioned already, I just buy the manufacturers branded coolant. This way, I don't have guess on all the compatibility issues. I'm sure its a few more dollars, but can't be many in the grand scheme of things.

 

[rschudy]

I suspect that the recent web accounts of gelling are the result of mixing organic acid and ethylene glycol coolants, like Dex-Cool and good old green Prestone. There may also be compatibility issues with corrosion inhibitors and other additives, but I really don't know. I, like you, won't mix.

 

[chef2sail]

Thank you very much for your insights, experience, and corrections.

I came to this forum because I need to change the coolant in my Yanmar, and am struggling to determine what coolant to use. There is an abundance of misinformation on the web and I am trying to understand this without becoming a marine coolant expert. I pasted below a Yanmar service bulletin, reprinted from Mac Boring. I think that the engine manufacturers are also unsure, because not enough time has passed since the new coolant formulations.

Thanks again. I hope that we can reach some kind of shared understanding, if not a consensus.
-Bob Schudy

TO: MARINE DISTRIBUTERS
COOLANT ADDITIVES
After testing some popular coolant/anti-freeze solutions, we have reached the following recommendations. It was not possible to test all brands on the market, so there may be some solutions that are acceptable but have not been tested. However, caution is advised if using other than approved brands. Regardless of the recommendation of the coolant/antifreeze manufacturers it is YANMAR'S requirement that the solution is changed every 500 hours (On the YANMAR Model 6LP 250 hours) or once a year whichever comes first. We do not recommend any other additives be added to the cooling system. Purified or distilled water mixed with the approved coolant/anti-freeze is the only protection approved by YANMAR.
Concentrations of the mixture should follow the recommendations of the manufacturer. The coolant/anti-freeze must be compatible with aluminum.

Advantages of this type of coolant:
• Improved water pump life due to reduced water pump seal wear resulting from fewer abrasive dissolved solids.
• Reduces hard water scale.
• Offers excellent protection against pitting corrosion caused by cylinder liner cavitation. Better heat transfer than conventional coolants with regular SCALE additions.
• No silicate gel formation during use or storage.
• Outstanding hot surface aluminum protection.
• Superior protection in high operating temperature conditions.
• Effective, long-term corrosion protection for aluminum, brass, cast iron, steel, solder and copper alloys.

The coolant/anti-freezes that have been tested and approved are shown below:
• Texaco Long Life Coolant Anti-Freeze both regular and pre-mixed Product codes 7991 and 7998. This product is available in gallon containers, drums and bulk. It is recommended that the cooling system be drained and flushed before filling. Only Texaco Long Life Coolant should be used for top-off. This product has a much longer shelf life than conventional coolants provided
the integrity of the container is maintained. For additional information and availability contact Texaco at 1-800-782-7852.
• Havoline Extended Life Anti-Freeze/Coolant. Product code 7994. This product is available through Texaco gas stations, Procedures are the same as with Texaco Long Life Coolant Anti-Freeze.
• Dex-Cool Long Life Coolant. This product is available through GM service centers worldwide.
• Prestone Extended Life Coolant. Product code AF888. If the above coolants are not readily available, Prestone Extended life coolant is satisfactory.

Prestone AF888 is Dex-Cool formulation.
Havoline 7994 is ethylene glycol formulation.
i haven't found information on Texaco 7991, which is apparently hard to fi
All four are long-life.

Thank you for posting for others,
We have followed this protocol for the last 16 years with zero issues.

If you own a Yanmar which many do why risk using anything else

 

[pdqaltair]

...Prestone AF888 is Dex-Cool formulation.
Havoline 7994 is ethylene glycol formulation.
i haven't found information on Texaco 7991, which is apparently hard to find.
All four are long-life.

Texaco 7991 has been re-numbered as 7997, which is the pre-dilute version of 7998.

 

[eherlihy]

When changing from one brand/color antifreeze to another many people "flush" the system with distilled water.

Rather than run a bunch of distilled water through the system, and then have to dispose of it and try to get back to the correct concentration (because I only use pre-mixed) here is what I did; I drained the old (green EG) antifreeze and filled with the new antifreeze (blue EG) then used the boat for a week as I normally do. I then changed the coolant (from 95% blue 5% green to 100% blue). The next season I changed coolant again. Since then I simply change every 3 years.

Fleetguard ES Compleat is claimed to be; compatable with all other coolants, good for up to 1 MILLION miles ('cha - right), and compatable with aluminum and solder components. It was selected by Practical Sailor as their top pick for diesel engine coolants. The datasheet on it is available here; https://www.cumminsfiltration.com/sites/default/files/LT15070.pdf

Posting this for anyone that may want to use this coolant. I have no financial or other interest in Cummins Filtration.

 

[pdqaltair]

A few things that might not be known:

* The "flushing" requires a light acid wash to remove the previous silicate passivizing layer. If this is not done, spotty protection with the new coolant is possible. HOWEVER, this only applies to aluminum cylinder heads and aluminum radiators, which are scarce as hems teath on boats. Otherwise, a quick drain and rinse is enough.

* There is no standard for "long-life engine coolant." They've been arguing over this for years, and the reason are both complex and technical, as well as political.

* Organic acids are used as corrosion inhibitors, typically on the order of a few percent. The acids used vary, as do their compatibility with elastomers. This is the primary area of disagreement.

*Bugs only grow in engine coolant or antifreeze (potable water system) if the pH is below 10 and the glycol concentration is below about 20%. The same reason brandy keeps and wine goes bad. And engine should NEVER have the freshwater coolant below 40% because corrosion protection will suffer.

* Dexcool was the first long life, and as a result of that inexperience, there was a small formulation error. That was rectified about 15 years ago and is old news. Dexcool is now licensed by numerous companies and is considered one of the best, most proven formulations. The patents also ran out, so the price came down.

There are very few good antifreeze products made these days that do not contain OAT (a few for heavy trucks and industry, but you won't find them at NAPA or WM). The reason, of course, is that ALL OEM vehicles used OAT coolants. Just flush and change with the times. The new stuff is better.

 

[eherlihy]

A few things that might not be known:

* The "flushing" requires a light acid wash to remove the previous silicate passivizing layer. If this is not done, spotty protection with the new coolant is possible. HOWEVER, this only applies to aluminum cylinder heads and aluminum radiators, which are scarce as hems teath on boats. Otherwise, a quick drain and rinse is enough.
...

I don't know of ANYONE that has ever done a light acid wash prior to or after a flush. Perhaps it is not relevant because there is no aluminum in my Universal/Kubota cooling system or engine block.

Can you elaborate on what you mean by "spotty protection?" Protection from corrosion in spots?

This is of particular interest to me as I have used a similar procedure when converting my motorcycle's coolant from unknown green to Toyota Long Life Coolant (a silicate-free OAT coolant which is red) and distilled water. The bike has an aluminum radiator. Any coolant in the motorcycle was supposed to be silicate free, but I have no idea what the green was because I bought the bike used.

 

[pdqaltair]

I don't know of ANYONE that has ever done a light acid wash prior to or after a flush. Perhaps it is not relevant because there is no aluminum in my Universal/Kubota cooling system or engine block.

Can you elaborate on what you mean by "spotty protection?" Protection from corrosion in spots?

This is of particular interest to me as I have used a similar procedure when converting my motorcycle's coolant from unknown green to Toyota Long Life Coolant (a silicate-free OAT coolant which is red) and distilled water. The bike has an aluminum radiator. Any coolant in the motorcycle was supposed to be silicate free, but I have no idea what the green was because I bought the bike used.

Coolant flush products have always been weak acid, typically inhibitied citric. If you don't have aluminum, don't bother.

The spotty corrosion was probably just an issue with the old formulation. Basically, the additives competed and there could be corrosion in the boundary areas. But is was generally minor, and so long as you flush, a non-problem.

The big problems happened when someone poured Dexcool in with a high silicate AF. This was most caused by misunderstanding and marketing people saying Dexcool was the greatest for everything.

BTW, some green Japanese coolants were always non-silicate. Toyota green was one of these. Never go by color. Some of the yellow or orange AFs have silicate now, and are not long life. It's crazy.

 

[rschudy]

Thanks All,

I want to explain a little of my background that led to my misunderstanding. My main coolant training and experience is with coolants for hydronic, solar, ground source heat pump, and dry coolers for computer air conditioners. For many years all that has been used in these applications is propylene glycol, because these systems need to run for decades with no more maintenance than occasional pH and corrosion inhibitor checks. I think that propylene glycol is used because of its lower toxicity and because it doesn't gum up. Recently I have learned that denatured ethanol is being used in some ground source heat pump and other applications, because it doesn't increase the viscosity or reduce the specific heat of water as much as the glycols. I enountered one long-life low-toxicity automotive coolant based on propylene glycol in an auto part store and incorrectly assumed that all of the new long-life coolants were based on propylene glycol, when apparently very few are. I completely missed the organic acid technologies used in Dex-Cool and similar long-life coolants. Cleaning and flushing large propylene glycol systems to change coolant types could cost tens of thousands of dollars, and they can have hundreds of polymer seals, and unknown components in dark places, so no one is going to experiment with changing coolants.

Sorry about my confusion, and thanks for the corrections,
Bob

 

[haydenwse]

If you want to use a non-toxic antifreeze in your engine this is a common one that I was able to get at my local NAPA for use in my hydronic system so that I did not need to worry about poisoning myself if the system leaked into my potable water system. https://peakauto.com/products/antifreeze-coolants/automotive/sierra/

It is based on Propylene glycol that is GRAS (Generally regarded as safe) rather than ethylene glycol. It meets all of the standards for engine antifreeze.

"SIERRA Antifreeze + Coolant demonstrates excellent corrosion prevention performance in all standard industry tests. Meets all of GM 1899 and GM 1825, ASTM D3306, including ASTM D1384 (Glassware Corrosion), ASTM D4340 (Hot Surface Aluminum Corrosion), ASTM D2570 (Simulated Service) and ASTM D2809 (Cavitation Erosion Corrosion-Aluminum Pumps)."

 

[bill wilkinson]

I have always been told. Fresh water cooled engines. If you have drained your engine block for the winter you can add rv or marine antifreeze for the winter for protection. It runs out when you start your engine spring.
correct?

 

[Minnewaska]

I have always been told. Fresh water cooled engines. If you have drained your engine block for the winter you can add rv or marine antifreeze for the winter for protection. It runs out when you start your engine spring.
correct?

First to confirm nomenclature. Fresh water cooled means there is a circuit that cools the engine, which contains a captive recirculating coolant. This coolant should be rated not to freeze, as well, down to a defined temperature, so it is also called antifreeze. Assuming it’s in good shape, it’s does not need to be drained. When there is a coolant circuit, the heat is removed, from the coolant, in a heat exchanger, which has raw water pumped from outside the boat, thru this exchanger, which is then expelled along with the exhaust gases. Raw water can either be fresh or salt. If this is what you have, you only need to draw a winterizing antifreeze thru the raw water circuit. Any residual would be expelled at start up in the spring. I prefer -100f rated for this, as it may mix with some raw water, which dilutes its impact and raises the freezing temp. Keep in mind, the ratings are for bursting, not freezing. The freeze point is much warmer.

If, however, you have a raw water cooled engine, there is no captive recirculating coolant. The raw water pumped in from outside the boat can be either fresh or salt and directly circulates around the engine, for cooling, and is then expelled. In this case, the thermostat needs to be removed and the block should be drained of this raw water. It is then best practice to circulate a descaler through the engine to clean the passages inside the iron engine that corrode. The coolant referenced in the above paragraph contains anti-corossion additives, so this isn’t necessary. After descaling, some still run anti freeze through for belt and suspenders, to be sure there is no residual water. Captain‘s choice.

 

[pdqaltair]

a. You use engine coolant in an engine, not antifreeze.

b. West marine only sells two engine coolants, and they are $67/gallon (concentrate) which is ... ludicrous. You should be able to get what you need for about $20 for predilute and $40 for concentrate.

You probably want predilute, because it is made up with distilled water (tap water does not meet spec for engines that run coolant instead of seawater).

 

[haydenwse]

a. You use engine coolant in an engine, not antifreeze.

b. West marine only sells two engine coolants, and they are $67/gallon (concentrate) which is ... ludicrous. You should be able to get what you need for about $20 for predilute and $40 for concentrate.

You probably want predilute, because it is made up with distilled water (tap water does not meet spec for engines that run coolant instead of seawater).

I use Peek Sierra, which is a pet safe, poly propylene engine coolant that has anti-freeze protection down to -25º
I would never buy my engine coolant from WM.

 

[Minnewaska]

Since different types of engine coolant have been mentioned, it’s critical not to mix any amount of any of them. The wring combo can gel inside your engine. If you’re not sure what’s in there, flush it all out with water first. Several times.