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Old 02-02-2004, 09:42 AM
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AntiFreeze Use in Large Diesels

This isn't really M-B related but just an interesting diesel related question.

I was speaking with my father-in-law yesterday after he and my nephew had come back from touring the USS Ling, a WWII sub open as a museum in Hackensack, NJ. They had focused on the diesel powerplant on the sub and had gotten into a discussion with the tourguide and another guest. One of the other gentlemen claimed that large diesels - the type used in locomotives and moderate sized ships - did not use any antifreeze in the coolant since the coolant and oil often mixed. My father-in-law (and I) found this very surprising and were wondering if there were any truth to these statements.

Anyone have any ideas?


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Old 02-02-2004, 10:43 AM
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Unlikely that there is much truth in that statement about coolant and lubricant mixing.
More likely they did not need antifreeze in the engines because the sea water rarely gets below 0'C and in those cases the engine would most likely be running.
Once a submarine dived, the water temperature would be above 0'C because water from 4'C to 0'C gets lighter as it cools (that is why icebergs float)
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Old 02-02-2004, 12:39 PM
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I don't believe that locomotives use anything more than water and possibly an anti-corrosive additive. Most of them are set up to dump their coolant when it cools to a certain temp (at least they were) to prevent it freezing and cracking the block. I think the newer ones have some sort of setup to keep things warm when they are shut down now.......... there was a long discussion of this on some other Diesel site. (I think either TDR or Diesel Truck Resource)
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Old 02-02-2004, 12:58 PM
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I'd bet they use a glycol based coolant -- if not, not only will they freeze, but the coolling system will not work very well. Dont' know for sure, but a full anticorrosion system is necessary, and unpressurized cooling systems aren't worth much.

No need to save weight in a locomotive, quite the opposite (normal weight is in the 750,000 lb range), but I do know that not all of them are in use every day, nor continuously, and dumping the anticorrosion fluid all the time in the winter is wasteful.

Marine diesels may or may not be directly cooled. WWII diesel US subs are simply railroad locomotive packages, but probably had indirect cooling -- seawater would cause too much trouble (corrosion and the possiblity of salt accumulation if overheated).

The ability of the US to drop a well known and well developed train genset into the subs was a distinct advantage -- they performed beautifully, and having been developed for moneymaking companies, weren't prone to having weird parts or excessive maintenance requirements. The German sub engines, while very good, were considerably more tempermental. Open rockers on those, by the way -- must have made for VERY messy engine rooms!

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Old 02-02-2004, 01:44 PM
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Large marine diesels (and stationary power plant engines) often do not run antifreeze, even in cold conditions. The reason is that the heat transfer ability of glycol-water mix is less than that of pure water. The more glycol, the poorer heat transfer ability.

The cooling passages in the heads and blocks of these engines are designed for a given flow with a given heat transfer ability, and if you put in glycol beyond a certain point, you typically derate the engine based on a curve, output vs. glycol percent.

To deal with very cold conditions, an interposing heat exchanger is used, wherein glycol water mix is circulated through the radiator, and on the other side of the exchanger the engine loop with "just" water circulates.

Engines like these do run corrosion inhibitors, and careful water treatment is very important, just as keeping your coolant in good shape in your car engine.

Ships generally have sea water heat exchangers, with treated water in the engine and raw sea water on the other side. No glycol in the picture.

I can't speak of what the practice is or was in WWII subs, however, just today!

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Old 02-02-2004, 03:12 PM
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Some marine engines do cool on just raw water. Outboards do and some I/O's and inboards. In this system seawater circulates around the block and threw the manifolds. I would not buy a boat that I plan on keeping longer than 5 years thats not fresh water cooled. That is usually how long it takes the salt water to eat threw the manifold and fill the cylinders. However raw water cooling is fine on lakes and rivers, just as long as theres no salt. I am going to ask my dad if the generators on the sub he was on used anti-freeze or were just raw water cooled. It's a newer nuclear boat though, not anything like WW2 subs.
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Old 02-02-2004, 04:02 PM
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Thanks for all the interesting and informative info. I'll pass this on to my father-in-law tonight.


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Old 02-02-2004, 05:55 PM
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I believe that glycol is added as both an antifreeze and to marginally raise the boiling point of the coolant. Dieseldiehard is right about the less effective heat transfer. Ask any racing mechanic and they'll tell you the preferred coolant is water with a lubricant/anticorrosion additive.
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Old 02-02-2004, 09:50 PM
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Ditto to dieseldiehard's story. Back in high school, my buddy also thought "if a little antifreeze is good, 100% should be super!" A month later he told me he junked his hand-me-down 65 Ford because it was billowing white smoke from the exhaust and it wasn't worth fixing! Oh well - I'm sure glad we got our mistakes out of the way early before we started buying REAL cars.
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Old 02-02-2004, 09:52 PM
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A proper antifreeze coolant is a mixture of 4 major components:

1) Ethylene Glycol HO-CH2-CH2-OH

Ethylene Glycol is used because it provides 2 important advantages.

- In a proper mixture of ethylene glycol and water, ethylene glycol
helps lower the FREEZING point and raise the BOILING point of the mixture at the same time. This will protect a cooling system in either very cold weather or under extreme heat conditions generated by engine combustion.

- It is very stable, non corrosive, and does not degrade under highly variable and harsh conditions of a cooling system.

A mixture of 70% (by volume) ethylene glycol and 30% (by volume) water provides the LOWEST freezing point and HIGHEST boiling point, and it's the most desirable combination if freezing and overheating problems are critical. Higher concentrations (by volume) of ethylene glycol will actually raise the freezing point and lower the boiling point of the mixture. Also, the most important reason why a higher concentration of antifreeze is not recommended is because pure ethylene glycol has extremely high surface tension and heat specificity. These properties tend to cause ethylene glycol to retain its heat, and its heat transfer ability to be very low. Water must be present to "wet" the metal surface (e.g. radiator) by lowering the surface tension in order to increase the heat transfer ability of the mixture.

Ethylene Glycol does raise the boiling point of a water/antifreeze mixture, but not quite a lot. Therefore, a cooling system needs to be under pressure (about 15 PSI, not enough to blow up a radiator or coolant hoses) when it's hot because higher pressure means that water/ethylene glycol molecules must have higher average kinetic energy in order to jump out of the mixture's surface to trigger the boiling process. Average kinetic energy of molecules/atoms is proportional to the temperature via the relation E(k) = (3/2) * k * T , where k = Boltzmann constant = 1.38065 * 10^(-23) J/K, and T = absolute temperate in Kelvin = 273.15 + C = 273.15 + (5/9)*(F - 32)


2) Water H2O

Water alone only provides freezing and overheating protection at 0 degree Celcius and 100 degree Celcius respectively, so antifreeze (mostly ethylene glycol) is required. The most important reason for the presence of water is to help increase the heat transfer ability of the mixture, so that the radiator can easily dissipate heat from the coolant mixture. This is accomplished by lowering the surface tension of the mixture molecules against metal surfaces.

Some coolant additive such as Redline WaterWetter may actually increase the heat transfer efficiency by reducing the surface tension even further. Redline WaterWetter also comes with some proprietary corrosion inhibitors.


3) Corrosion inhibitors

These substances are designed specifically to protect the metal surface of radiator, engine etc... Because an optimal mixture
requires both water (corrosive) and ethylene glycol (non-corrosive, almost non-reactive), corrosion inhibitors must be present to counter the corrosive effect of water.

The reason why you have to change antifreeze coolant every few years is to replenish the proper amount of corrosion inhibitors. Corrosion inhibitors usually start to deteriorate after several years.

The only difference between different kinds of antifreeze is the corrosion inhibitor package and water pump lubricant. The corrosion inhibitor packages in various kinds of antifreeze are:

- Conventional American Green antifreeze = silicate, phosphate

- GM-spec Dexcool (orange) = organic acids only (no silicate/phosphate)

- Japanese antifreeze (green, purple, red ...) = no silicate but high phosphate, plus some other proprietary inhibitors.

- European antifreeze (G-05, G-11,G-12, G48) = very little silicate (no phosphate) to be backward compatible, organic acids (different from Dexcool)


4) Water pump lubricant

It's used to lubricate a water pump's seals.


Some new less toxic antifreezes use Propylene Glycol (OH-CH2-CH2-CH2-OH) instead of Ethylene Glycol (OH-CH2-CH2-OH). However, antifreezes using Propylene Glycol are not as efficient as those using Ethylene Glycol, because the heat capacity of Ethylene Glycol is higher at 0.85 Cal/g*K as compared to Propylene Glycol at 0.6 Cal/g*K

Hope this helps.

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Old 02-02-2004, 10:15 PM
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To cover the locomotive side of this question, they are generally not shut down and can thereby get away with no antifreeze. Cooling systems are shuttered for low temps and on some locos extra fans were removed in winter. The locos also don't use antifreeze for the above mentioned heat exchange reasons and because of cost, those systems hold a huge amount of coolant. If they are shut down it is either in a heated building, a block heater or equivalent is supplied, or the block is drained.
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