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#614051 - 01/03/05 01:42 AM Diesel engine coolant?
55Test Offline


Registered: 09/22/04
Posts: 1972
Loc: New Brunswick
What's the deal with diesel engine coolant? How is it different from coolant used in a gasoline engine?

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#614052 - 01/03/05 05:36 AM Re: Diesel engine coolant?
Mickey_M Offline


Registered: 08/13/04
Posts: 1001
Loc: Baltimore
quote:
Originally posted by 55:
What's the deal with diesel engine coolant? How is it different from coolant used in a gasoline engine?

Here’s the quick answer:

http://www.off-road.com/ford/news/2003_07/coolant/

“Every time the pistons move up and down, they rock in the bore, causing the cylinder wall to vibrate. Vapor bubbles can form on the outside of the cylinder wall as it moves inward, or away from the coolant, creating a low-pressure area. When the cylinder wall moves outward, or into the coolant, the pressure increases on the vapor bubbles. After many cycles, vapor bubbles continue to form and the pressure on the bubbles increases until, finally, a vapor bubble collapses.

When this happens, it creates a localized stress area of more than 50,000 psi. The high pressure and heat created by the implosion removes a small amount of cylinder wall material where the vapor bubble was attached. Over time, the cylinder wall can continue to erode, and eventually may form a pinhole in the wall that allows coolant to enter the combustion chamber, leading to possible engine failure.”

“Unlike diesel engines, gas engines do not need
cavitation protection. This is because diesel engines are more likely to be used in heavy-duty applications and operate under higher loads for longer periods of time. By nature, diesel engines often have cylinder pressures greater than twice the cylinder pressure of a gasoline engine. This combination of high load and high combustion pressures creates the violent cylinder wall vibrations that lead to cavitation. Most gasoline
engines will not experience enough of this kind of
operation in its life to cause a failure. Although
rare, there have been occurrences where a gasoline
engine did fail from cavitation erosion.”

The single ingredient missing from many automotive
long-life coolants is nitrite in one form or another.

It is in all the diesel coolants.

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#614053 - 01/03/05 07:28 AM Re: Diesel engine coolant?
Michael Polutta Offline


Registered: 10/14/04
Posts: 140
Loc: Atlanta
Is there any benefit to running diesel coolant in a gasoline engine? Is there any danger/downside?

Just curious...

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#614054 - 01/03/05 10:59 AM Re: Diesel engine coolant?
ChrisW Offline


Registered: 11/04/03
Posts: 943
Loc: Central Valley, CA
G 05 spec coolant is a precharged formula, and is ok to use in gas or diesel applications. If Ford and Chrysler are using it in gas cooling systems with no problems so far, and also in diesels (like the powerstroke diesel), I haven't seen a problem yet from using a "precharged" coolant in a gas engine. If anything, it would resist cavitation better than a gas engine only coolant.

Also, it has to do somthing with wetsleeve systems, though I don't know the full details as to why, I do know that diesels are wet sleeved, or most i think.

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#614055 - 01/03/05 04:35 PM Re: Diesel engine coolant?
Mickey_M Offline


Registered: 08/13/04
Posts: 1001
Loc: Baltimore
quote:
Originally posted by Michael Polutta:
Is there any benefit to running diesel coolant in a gasoline engine? Is there any danger/downside?

Just curious...

It can be a little rough on water pump seals.

Other than that it's "no" on both counts.

People who have mixed fleets often use diesel coolant in all of them to be safe - you'll never accidentally fill or top off a diesel with a non-diesel coolant that way.

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#614056 - 01/03/05 04:36 PM Re: Diesel engine coolant?
Mickey_M Offline


Registered: 08/13/04
Posts: 1001
Loc: Baltimore
quote:
Originally posted by ChrisW:
G 05 spec coolant is a precharged formula, and is ok to use in gas or diesel applications. If Ford and Chrysler are using it in gas cooling systems with no problems so far, and also in diesels (like the powerstroke diesel), I haven't seen a problem yet from using a "precharged" coolant in a gas engine. If anything, it would resist cavitation better than a gas engine only coolant.

Also, it has to do somthing with wetsleeve systems, though I don't know the full details as to why, I do know that diesels are wet sleeved, or most i think.

"Wet sleeved" simply means that cavitation *could* be a problem. Coolant is circulating around the cylinder in a wet sleeve design.

The reason why G-05 can be used in diesels is because it contains nitrites. The full OAT formulae don't.

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#614057 - 01/04/05 08:24 AM Re: Diesel engine coolant?
1 FMF Offline


Registered: 08/12/02
Posts: 1680
Loc: CT
quote:
Every time the pistons move up and down, they rock in the bore, causing the cylinder wall to vibrate. Vapor bubbles can form on the outside of the cylinder wall...
Mickey I think has the definition of diesel cavitation explained really well, except for the part of what causes the cylinder wall to flex.

From what i've learned, the vapor bubbles which cause the cavitation are formed simply by the high cylinder pressures and compression ignition of fuel. Most gasoline engines, running < 93 octane, have < 11:1 compression ratios. Diesels are on the order of 17:1 to 24:1, thereabouts. Cylinder pressures of gas engines < 200 psi whereas the norm for diesels are > 300 psi, 500psi typical. Because diesels inject fuel into an already compressed air mixture, the fuel ignites spontaneously, which is detonation in terms of a gasoline engine and the reason diesels are loud and have that distinctive knock to them when they idle. Gas engines ignite fuel where the flame propogates evenly and smoothly in the cylinder, from the spark of the spark plug. A diesel, pardon the explaination, it's just an explosion as soon as the injector squirts fuel into the heat of the compressed air in the cylinder at TDC. The massive sudden increase in cylinder pressure, at high rpms heavy load, is enough to flex the cylinder walls. The details after that, are already explained.

Many diesels have "cylinder liners" with a coolant jacket around it. The liner, separating piston and combustion chamber from coolant jacket is relatively thin, A Design Flaw, and flexing is a possible. The harder the engine is run, the higher the rpms, and the higher the cylinder pressures or turbo boost pressures, all increase likelihood of cavitation.

Gas engines with cast iron blocks don't have liners, so there is no "liner flexing". Aluminum block gas engines do have cast iron liners, but the compression ratio (CR) is so low that there is, nor has ever been any problems to my knowledge, of liner flexing and cavitation.

The cavitation issue in a diesel is the cause for the proper type of coolant to be used. In many times with the proper additive, called SCA (supplemental coolant additive). Traditional green ethylene glycol antifreeze required the SCA to help prevent and/or protect from cavitation. Ford/Fleetguard type uses nitrites in combination with molybdate to form a sort of corrosion layer, so I've read, which builds up on the coolant side of the cylinder liner. When the vapor bubbles form, they eat the built up corrosion layer and not the metal of the liner. The other type of SCA is the penray type, which is mostly nitrite.

To add SCA to the traditional green ethylene glycol antifreeze, at 50/50 water/glycol mix, the antifreeze should be (must be or recommended, jury still out) low silicate, meeting ASTM 4985. High silicate antifreezes are reported to cause the SCA (nitrites and other additives) to fall out of solution in the coolant system and form a green goo sludge and damaging the cooling system. The old prestone green antifreeze in the yellow bottle, even though might say low silicate formula, is not low enough for diesel coolant and SCA standards apparently, and is not recommended. Rule of thumb is if it don't say ASTM 4985 on the bottle, don't use it with SCA.

Coolants/anti-freezes labeled as diesel coolants, which are of the traditional green ethylene glycol type, are the real low/no silicate formulas which can be mixed with SCA's.

SCA's also enhance the corrosion protection of the coolant, if used right. So it was not uncommon to add SCA's to green ethylene glycol in heavy-duty type gasoline engines.

The silicate in coolant is abrasive and can lead to water pump and seal failure. High amounts of SCA (nitrites) are also abrasive and cause the same problem over time. There are ppm limits to amounts of SCA that should be added, partly because of abrasive wear but mainly due to it falling out of solution and inhibiting cooling.

New extended life coolants, hybrid organic acid techonolgy (OAT or HOAT) as they are called, are formulated differently and are apparently not as susceptible to cavitation like the old green stuff. The end result of cavitation, is a hole in the cylinder liner... coolant gets in cylinder, hydrolocks and results in an expensive rebuild.

The ford IDI (indirect-injected) and powerstroke DI (direct-injected) engines, made by International-Harvester actually, from the mid 1980's to mid 1990's from what I read are most prone to cavitation.

Ford has never acknowledged the cavitation problem, nor warrantied any ruined engines from it, nor published a TSB on the problem to my knowledge. However Ford does sell SCA, known as FW-16. Used to be FW-15 early on I think, but just relabelled Fleetguard DCA-4. Many Ford diesel ownwers, especially those who've experienced cavitation, are not happy about this.

Cavitation reports occur most between mileage of 100000-150000 on the engine. I have a 1989 F-250, 7.3L IDI, with 141000 miles, that's how I know all this [Wink]

dieselstop.com in the IDI forum will have lots of info on cavitation. A web search on keywords SCA and Cavitation will bring up lots of info. For more detail on SCA, check out http://www.imcool.com/articles/antifreeze-coolant/SCA-Part1.htm

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#614058 - 01/04/05 10:18 PM Re: Diesel engine coolant?
Big Jim Offline


Registered: 09/24/04
Posts: 1571
Loc: Thousand Oaks, CA
quote:

From what i've learned, the vapor bubbles which cause the cavitation are formed simply by the high cylinder pressures and compression ignition of fuel. Most gasoline engines, running < 93 octane, have < 11:1 compression ratios. Diesels are on the order of 17:1 to 24:1, thereabouts. Cylinder pressures of gas engines < 200 psi whereas the norm for diesels are > 300 psi, 500psi typical. [/QB]

A minor detail, but you cylinder pressures are way off. The readings you provided are typical cranking compression readings on an engine that isn't running. Actual pressures with the engine running, especially under load are much higher, and yes, they are much higher still on a diesel compared to gasoline engine.

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#614059 - 01/05/05 12:27 AM Re: Diesel engine coolant?
CoolantChemist Offline


Registered: 12/14/04
Posts: 49
Loc: Illinois
FW15 "Ford has never acknowledged the cavitation problem, nor warrantied any ruined engines from it, nor published a TSB on the problem to my knowledge. However Ford does sell SCA, known as FW-16. Used to be FW-15 early on I think, but just relabelled Fleetguard DCA-4. Many Ford diesel ownwers, especially those who've experienced cavitation, are not happy about this."

Are you saying there is a problem with DCA-4? If so, what are your concerns? I can probably clear up any misconceptions you might have.

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#614060 - 01/05/05 07:22 PM Re: Diesel engine coolant?
Stinky Peterson Offline



Registered: 05/15/03
Posts: 383
Loc: Bismarck, North Dakota
1 FMF, thanks you did a good job of explaining things. There is some disagreement about the actual mechanism of cavitation erosion/corrosion. What is know is that bubbles and vibrations are involved. When the liners move in the bubbles are formed, however I've always had trouble accepting the idea that the collapse of the bubbles are what cause the problem. It's true the cavitation will cause big problems in hydraulic pumps where there is a change from a negative pressure on the suction side of the pump to the pressure side which may be 6000 psi or more. Here when the bubble collapses there is a sudden pressure applied in a small area. In engines the pressures are no where near this high and I do not believe there is enough energy to directly erode the surface.

It is reasonable to believe that the coatings formed on the liner are compromised when these bubbles collapse but part of the damage is causes by the sudden application of cooler water to the hot surface of the liner. Where there are bubbles there is no coolant so the surface gets very hot. When the water hits the hot surface it erode/corrodes the surface and causes a small amount of material to be removed. The presence of oxygen also plays a role and it one of the biggest problems for cooling system.

Here are a few factors.

- Dissolved O2 (oxygen) is present in the coolant

- Mechanical energy initiates a reaction between the O2 and Fe

- If O2 above critical level Fe3O4 (black iron oxide or scale) forms. This material is like the scale formed from a cutting torch.

- If O2 less than critical level Fe(OH)2 Iron II Hydroxide forms which oxidizes to Fe2O3 (rust)

- If no O2 is present no reaction takes place

- Fluid near boiling point (low glycol), low pressure, or high temp

- Accentuated where vibrations occurs at resonant frequencies of the liner system and particularly at the critical frequency

- The Fe3O4 blasted off by the next implosion of the cavitation cycle leaving a cavity where the dissolved O2 depletes and Fe2O3 forms

I've seen cases where there is erosion on only one or two cylinders and upon close inspection the crankshaft was found to bent by 0.015" on the same end as the bad liners.

This explanation is not universally accepted but it makes good sense to me. It was proposed by one of the engineers I know at Cat.

Stinky

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#614061 - 01/06/05 05:54 AM Re: Diesel engine coolant?
Mickey_M Offline


Registered: 08/13/04
Posts: 1001
Loc: Baltimore
quote:
Originally posted by Stinky Peterson:
.... There is some disagreement about the actual mechanism of cavitation erosion/corrosion. What is know is that bubbles and vibrations are involved. When the liners move in the bubbles are formed, however I've always had trouble accepting the idea that the collapse of the bubbles are what cause the problem. ....

There is a very similar problem with props on large ships, and there the research extends back to before WWI that it's the collapse of bubbles that causes the erosion.

Also, while 1 FMF is correct about sleeved engines (liners) aggravating the situation, GM experienced the same problem on the unsleeved converted gasoline engines in Cadillacs etc in the '80s where the thin-wall castings eroded around the cylinders.

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#614062 - 01/06/05 09:59 PM Re: Diesel engine coolant?
1 FMF Offline


Registered: 08/12/02
Posts: 1680
Loc: CT
sorry about the cylinder pressure vs cranking pressure. you're supposed to know what I mean when I type something else [Razz]

no problems with DCA-4 that I've heard of or experienced. It seems to have fixed the problem with had started to become a common occurance before 200k miles, or xx hours, of service.

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#4573110 - 11/13/17 06:17 PM Re: Diesel engine coolant? [Re: 55Test]
Schuttwegraeumer Offline


Registered: 10/28/14
Posts: 19
Loc: Austria - Vienna
Are the US diesels completely different from the EU diesels?
Look at the Glysantin Chart:
G48 ist HOAT without nitrites.
The [url=Ghttp://www.glysantin.de/fileadmin/Files/Downloads/Folder/basf_glysantin_orientation-list_heavy-duty-vehicles_e.pdf][url=Ghttp://www.glysantin.de/fileadmin/Files/Downloads/Folder/basf_glysantin_orientation-list_heavy-duty-vehicles_e.pdf][url=Ghttp://www.glysantin.de/fileadmin/Files/Downloads/Folder/basf_glysantin_orientation-list_heavy-duty-vehicles_e.pdf]Ghttp://www.glysantin.de/fileadmin/Files/Downloads/Folder/basf_glysantin_orientation-list_heavy-duty-vehicles_e.pdf[/url][/url][/url]
G30 ist OAT and G40 is HOAT without nitrites.
Are not wet liners in the EU engines?
What additives are good against cavitation except nitrites?

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#4584145 - 11/25/17 02:18 AM Re: Diesel engine coolant? [Re: Schuttwegraeumer]
DS9 Offline


Registered: 07/10/13
Posts: 78
Loc: Belgrade, Serbia, Europe
https://www.constructionequipment.com/tackling-today%E2%80%99s-tough-coolant-questions



Granger:
Nitrite essentially provides a protective film by converting iron oxide from hematite (Fe2O3) to magnetite (Fe3O4), which is harder and prevents pitting. Since this reaction is irreversible, nitrite must be continuously replenished. With ELC (OAT) coolants, the carboxylate acid (RCOO-) in the OAT reacts with iron (Fe++) on the surface to provide a protective film of iron carboxylate (Fe(RCOO)2). Since this reaction is reversible, the OAT attaches only when needed with free iron ions and may provide protection for 600,000 miles or longer in a well maintained system. OAT coolants have demonstrated satisfactory protection of wet sleeve cylinder liners in the newly established ASTM D7583 John Deere Cavitation Test and are currently being used widely in heavy-duty diesel engines in Europe and Asia-Pacific, where nitrite is prohibited.

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#4619494 - 12/31/17 08:56 AM Re: Diesel engine coolant? [Re: 55Test]
Schuttwegraeumer Offline


Registered: 10/28/14
Posts: 19
Loc: Austria - Vienna
The OAT last longer.
But is OAT protection as good as nitrite protection?
There are also nitrite-free coolants for heavy duty, for example from Zerex.
I do not know if there is molybdenum in there.
Which additives would protect cylinder liners against cavitation?

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