Coolant Question

I have an FL 120. I just changed all coolant hoses, t-stat, water pump, and the two steel cooling pipes on the starboard side of the motor.

As I was refilling the motor I was mixing 1/2 distilled water and 1/2 Napa brand green antifreeze. I would pour the antifreeze into a jug half full of distilled water and then pour it into the motor. I noticed that the mix was warm almost like the water and antifreeze were reacting to each other. I thought no that can not be and continued to fill the system. Now that it is done and the tools are put away I am thinking maybe distilled water was not such a good idea. So I did a google search and of course got conflicting reports some say that is the right thing to do and never use tap water while others say it is wrong.

Anybody here have an opinion? I don't want to drain the system and redo it, but will gladly do it if this is going to be harmful. The container just says to mix with water. It does not specify tap or distilled.

You're good with distilled water. That's even better than most tap waters since the tap water has/or can have more minerals in it.

Our diesel shop says it depends on the quality of the water in your area. Up here the water is such that using tap water in the 50:50 Cat diesel coolant mix is fine. Some people here even use tap water in their batteries with no apparent problems although we don't.

In other locations distilled water cen be the better choice to mix with coolant.

What we don't do is run standard automotive coolant in our diesels. We run a coolant-- Cat brand in our case (don't know who actually makes it)-- that is formulated for diesels.

Larry,

I thought using distilled water was a no brainer, but as I did it I noticed the jug of mix was warm. At first I just though no that is my imagination, but after a couple of jugs I stopped and felt the next water jug and the antifreeze jug. Both were cool. I mixed the two togather and it became warm. Not hot but it was warm.

Marin said:

Our diesel shop says it depends on the quality of the water in your area. Up here the water is such that using tap water in the 50:50 Cat diesel coolant mix is fine. Some people here even use tap water in their batteries with no apparent problems although we don't.

In other locations distilled water cen be the better choice to mix with coolant.

What we don't do is run standard automotive coolant in our diesels. We run a coolant-- Cat brand in our case (don't know who actually makes it)-- that is formulated for diesels.

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Interesting, I don't know why I did not think to look for a coolant specificaly for diesels.

You're fine with the green stuff according to Bob Smith. Our FL's do not have a problem with cavitation or have aluminum parts which some of the other diesels do.

Good morning. You must use diesel coolant. Regular may not be formulated to prevent cylinder cavitation and you can actually damage your engine. Distilled water is best. If you have ever been in a hard water area and seen how the minerals coat everything it would be clear why distilled is best. If you buy the pink diesel stuff it should be good for 5 years or so. Also, use test strips to check the coolant so you will know when it needs remediating.

Think 'coolant,' not 'antifreeze,' although it does that too.

You are good with distilled water and "prestone" type antifreeze/coolant at 50/50 mix in the fl 120.

Smth told me the same...green, cheap antifreeze is fine...


On many diesels I might reconsider...but the Lehmans have enough history to prove the green cheapo stuff is fine.


Start playing with silicate levels and you have to monitor them close...you can always go for the OAT tech antifreeze...but why worry when the green has proved the test of time in that engine.

I use this in my coolant:

Red Line Synthetic Oil - WaterWetter® Coolant Additives

And in most every case I've seen a reduction in my coolant temperatures.

If you're really anal about your coolant, use this:

Evans Cooling » Home

The best coolant there is IMO.

I just changed mine and used 60/40 distilled water and AF. Tested to -10 degrees F. And the cooling system works better w less than half AF.

I did use extended life AF as my manual recomended it. However there's no aluminum in my system so I would have used old fashioned green had the manual not recomended LL.

From the small amount of research I did it seems w my kind or type of engine no special for diesel coolant is needed. I think it's the high output engines like 2hp per cu in that need the special coolant.

FL120s will most likely run for years if not decades on just about anything you put in them for coolant other than sand. When we bought our boat in 1998, being very inexperienced at this type of boating with this type of boat, we asked a lot of questions about the care and feeding of the engines. We talked to our diesel shop, of course, but also to acquaintences whose careers are or have been in the marine propulsion and generator manufacturing industry.

One thing that made it easy was all these folks were independently in agreement on the type and weight of oil we should use, how often we should change it, the type of coolant that would be best to use, warm up times, and operating range.

With regards to coolant, a coolant forumlated for use in diesel engines was strongly recommended. When we bought the boat both engines had "non-toxic" coolant in them. I believe it was Sierra brand. We were advised to immediately remove it and replace it with diesel coolant which we did.

There were several reasons behind the recommendation to use diesel-formulated coolant. One was the cavitation issue, which these folks said is present in all diesel engines, it's a matter of degree. Another reason was corrosion control. And there were a few other reasons which I have since forgotten.

In the overall scheme of things boating-cost-wise, coolant, like lube oil, filters, and fuel, is damn near free. So while it may be possible to save the price of a latte (in Seattle, anyway) by using automotive coolant like Prestone, NAPA (don't know who actually makes it for them), and so on it's one of those things that if we don't have to do it, we don't. So we use what's been recommended to us by people in the diesel industry.

I know Bob Smith says regular old anti-freeze is fine in the FL120 and he's probably correct for as long as most individuals will probably own a boat with these engines in them unless they have a lot of time on them. On the other hand..... Bob also insists that adding Marvel Mystery Oil to fuel is something that should be done for the FL120. This has been proven to be a Very Bad Idea in lubricity studies.

The coolant type is most certainly not as critical for an FL120 as it is for a newer generation diesel. But nevertheless it makes sense to us to use what has been recommended by multiple "experts" in the marine diesel industry.

so is dex-cool ok for diesels?

We've been told by several sources that regular old antifreeze is what to use in our Cummins 6BT with no aftercooler. I checked the Cummins website and the type they recommend (Cummins branded) is the plain stuff. They have another type that is recommended for the larger engines to prevent cavitation. Apparently not a problem with our little 220 HP version.

Larry M said:

...Our FL's do not have a problem with cavitation...

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Google cavitation/wet liners or cavitation/wet-sleeve liners, you get the idea. I have no problem running the green stuff in our FL. I can get it anywhere in the world and I don't have to worry about mixing different coolants.

"I don't have to worry about mixing different coolants. "

Perhaps, just like oil there are different additive packages in AF and mixing them may not be a great idea.

I would still use a 2 part cleaning and flush flush flush between brands ,,as well as every 3 years or so.

But what about the mixture becoming warm when mixing? That would seem to indicate a chemical reaction between the distilled water and the AF. Very strange. I would get another gallon of each and try it again checking with a thermometer this time. If I got the same heat reaction, I would find out why. That should not happen....

Marin,
I haven't looked at what kind of coolant to use re the cost of the coolant.
I viewed it as a decision to pick the best coolant for my engine in it's application.
It's much like what dino lube oil to use or what gas to use in my car. I don't need MV and as I see it there's no advantage significant enough to warrant the extra cost of syn oil and no reason at all to use high octane gas if you don't need it.

It's a matter of what's best for your application .. not just choosing a better product. SS would probably be better for much of my car but if I bought a SS car I wouldn't have a house to live in. So I have a reg steel car, 30wt oil for my boat engine because it's best for the application and I buy gas according to my car manual.

Brooksie said:

But what about the mixture becoming warm when mixing? That would seem to indicate a chemical reaction between the distilled water and the AF. Very strange. I would get another gallon of each and try it again checking with a thermometer this time. If I got the same heat reaction, I would find out why. That should not happen....

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Certain liquids, or solids and liquids, when combined will release or absorb energy and result in a cooling or warming of the solution. No chemical change will occur. Don't sweat it! As an example.... apply a copious amount of the ethanol containing hand sanitizer and drip a bit of water into your palms and lightly rub for a second. You will feel heat given off from the alcohol miscing with the water...yet the chemical compounds have not changed structure.

Regarding getting warm when mixing: I noticed the same and asked a chemist buddy. He went into a 15min dissertation that blew right over my head. Afterward I asked if it was normal and he said "yes".

Regarding dist water: That's what I use to mix with coolant. My well water sucks, so it's a no brainer. Water through a softener has Cl ions, no bueno.

Regarding coolant color/flavor: Low output non-linered engines like FL 120, 80, 6B cummins, a-ok to use old skool green. Anything with steel liners or with aluminum manifolds like Yanmar and Volvo, be picky and use what they suggest.

Regarding mixing flavors: Don't do it. Can't get all the old stuff out, and can't trust the co's when they say "compatible with anything". If green was in there, use green. If you must change flavors and don't know what was in there, flush the heck out of it til nothing but clear water, then load.

manyboats said:

M

It's a matter of what's best for your application .. not just choosing a better product.

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i don't disagree with that at all. However very often the best for the application is also the better product. Our Range Rover will run on 87 octane but the engine was designed to be run on higher octane so that's what we run it on. The engine in my new pickup was designed to run on 87 octane. It will actually run on E85 although the manual is worded in such a way as to imply one would be a fool to do it.. So i run it on 87 octane.

We use Cat diesel coolant in the engines on our boat. Is it absolutely necessary? Maybe not. But I prefer to follow the advice of people we know who are actually in the diesel engine manufacturing industry rather than a lot of conflicting anecdotal opinions on an amateur boating forum. And since nobody has said that coolant formulated for diesel engines is bad for the engines in our boat, it makes no sense to not use it, particularly when the overwhelming opinion of the folks we've talked to in the diesel engine industry is to use it.

In the case of coolant, the cost difference between using diesel coolant and the automotive "green stuff" is insignificant. Particularly when one figures in how seldom one has to buy it. It's not like fuel, which one has to buy all the time.

So that's why we do what we do. What other people do is what other people choose to do.

I had a half gallon of antifreeze left so I measured the temp of it and of the jug of distilled water then mixed them togather.

Antifreeze 85.6° It was stored in the ER.
Distilled Water 82.4° It was stored in a cabinet.
Mixed togather 94.2°

So it was not just my imagination.

It did begin to cool right away though.

The yellow Prestone antifreeze is a No No for Any diesel. It will "Scale" the tubes of your heat exchanger and Slowly over time begin to over hear your diesel. Two years of frustration before I figured this out!

Marin,
Many folks even in the marine industry have different opinions and recommendations. The only thing to do then is to buck up and get as objective as possible and look at all the variables. For example if we knew many skippers that have gone for decades using the green stuff we could be very correct and comfortable doing same. I lean too strongly at times to the think for myself way of coping w things but most often it works well. I used an ultra performance synthetic motorcycle racing oil in my UL aircraft engine when the manufacturer said don't use it. They said they didn't have time to test all the very different kinds of synthetic oil. So I did my own testing and it payed off.

READY2GO,
Thanks for taking the time to test.

READY2GO said:

I had a half gallon of antifreeze left so I measured the temp of it and of the jug of distilled water then mixed them togather.

Antifreeze 85.6° It was stored in the ER.
Distilled Water 82.4° It was stored in a cabinet.
Mixed togather 94.2°

So it was not just my imagination.

It did begin to cool right away though.

Click to expand...

Interesting... thanks

I'm using a long life organic acid coolant.
I'm not a big fan of the old school green coolant mainly due to the silicates used for protection. They are slightly abrasive and cause wear on bearings and impellers. The other problem is that they are sacrificial in nature, and lose their ability to protect your engine over time, whereas the protection of organic acid coolants does not diminish.

The only disadvantages with the OA coolants are that they shouldn't be mixed with the green stuff (and vice versa) and they are not suitable for old style copper radiators because it does not protect the lead solder.

Other than that - fill it up and your good to go for 5 years.

READY2GO said:

I had a half gallon of antifreeze left so I measured the temp of it and of the jug of distilled water then mixed them togather.

Antifreeze 85.6° It was stored in the ER.
Distilled Water 82.4° It was stored in a cabinet.
Mixed togather 94.2°

So it was not just my imagination.

It did begin to cool right away though.

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Just a guess - But I would say the antifreeze contained some ethylene, which when oxidises produces ethylene oxide. When that mixes with water, it causes a chemical reaction which produces ethylene glycol, (the main ingredient in antifreeze.)

Maybe your batch was short a pinch of water..

"The only disadvantages with the OA coolants are that they shouldn't be mixed with the green stuff (and vice versa) and they are not suitable for old style copper radiators because it does not protect the lead solder."

And how do you think your engines heat exchanger tubes are held in place?