Auto Service World
Feature   May 1, 2007   by Andrew Ross

Coolant Compatibility a Hot Topic

Few things will get an OEM engineer hot under the collar faster than suggesting that there is no difference in coolant formulations.

At least that’s if you believe Ed Eaton, whose Amalgatech Division of Amalgamated Laboratories, Inc. makes coolant testing an everyday obsession. He presented much of that obsession at the recent Mobile Air Conditioning Society Worldwide conference in Phoenix.

“There is so much going on and so much debate, and a lot of variety in the marketplace right now,” Eaton said. There are, he explained, a number of issues to watch very carefully regarding coolant these days. He warned that market forces that have driven up the price of EG have created a market for the unscrupulous–“there is even a group of people out there, given that there is fairly high ethylene glycol pricing, offering coolants that are made from industrial waste fluids”–and the growing market for recycled coolants has yielded a similar rogues’ gallery of players.

Troubling results were found in a survey of 15 recycled coolants sourced from fast lubes and presented to the ASTM coolant committee, said Eaton.

“Of the 15 samples, only three met the ASTM spec, 12 did not, and some of them were really, really bad. They were recycled but still had all the oxidation products and the old inhibitors and contaminants. And they were being sold at the same price as the three that passed.”

So buyer beware, he said. “Any time somebody is [recycling coolant] on your property with a filter, that’s not recycling. You want the glycol and the water, but that’s all.

“Watch for coolants that smell wrong. If they smell wrong, they are wrong. We have come across coolants that are orange- and lemon-scented in an effort to cover up a bad smell. Why would you do that if you are not trying to cover something up?

“We have seen engine failures in thirty days when these coolants are added to a cooling system.”

Aside from these bad actors, there remains much to be concerned about in the legitimate market. With the emergence of several newer formulations, the days when green was the only colour in the coolant rainbow are long gone.

“People forget that that coolant does more than cool; it must provide freeze protection, boil-over protection, corrosion protection, and prevent scale formation on heavy-duty engines,” observed Eaton. The current offerings on the market are a product of nearly a century of development of what started out as simple water, moved to an alcohol solution, then to water and ethylene glycol, and further through continually developed additive packages that served to protect the materials through which the coolant flowed. And, of course, propylene glycol-based coolants made some inroads on the grounds that they had lower toxicity.

Today, the coolant world is complicated by the fact that different OEMs have chosen different coolant technologies, in order to maximize the reliability not only of the coolant, but also of the materials used in the engine and cooling system.

And while it is clear from some of the questions and comments from the day-long track that not everyone believes that this is the case (one attendee, who works mostly on Class 8 trucks, has taken to wholesale replacement of the Dex-Cool package with conventional green coolant), Eaton told attendees that it is a mistake to view the diversity of coolants as merely politically driven.

“There are some real differences,” he said. Engineers at all OEMs have made decisions about materials to use in their engines, and have made selections of coolant technologies designed to perform well in that environment. Materials and alloys are not the same from one OEM to the next, and they do not like the idea that the wrong coolant may be used and end up compromising the life of those components.

“‘Hate’ isn’t a strong enough word for how Ford engineers feel about Dex-Cool,” he added.

There are, essentially, three types of coolant technologies currently out there. These include conventional, usually green, inorganic additive technology (IAT) coolant; Organic Acid Technology (OAT), most commonly known as Dex-Cool, which GM is committed to for the foreseeable future; and Hybrid Organic Acid Technology (HOAT), which many may see as G-05, and which has been adopted by Ford, Daimler Chrysler, and several others.

The proliferation of coolant technologies has caused a desire to limit the amount of variety needed by those who sell coolant, which in turn has led some companies to claim universal compatibility with their products. These claims raised a few eyebrows, and at least a few of those were at the U.S. Federal Trade Commission, which asked at least one supplier to cease making that claim until further testing could be performed.

Attention has mainly focused on HOAT and OAT coolants, which are essentially European formulations, distinct from the silicate-free coolants favoured by Asian automakers.

“Essentially the suppliers of hybrid coolants, and the suppliers of OAT-type coolants, do not agree on the compatibility of each other’s coolants with everybody else’s.”

There are some other options that may appear down the road, he told attendees. One of these is glycerine, which is in increasing supply as a by-product of increased biodiesel production; Eaton has been studying another, propylene diol (PDO), for some time. In fact, an SAE paper he coauthored in 2001 with Shell engineers W. H. Boon and Chris J. Smith stated, “PDO appears to offer intriguing advantages. [Data] reveal potential advantages in corrosion protection, in particular, protection against lead solder corrosion,” in addition to other benefits.

Today, though there is a lot of talk on the street of “universal compatibility” but little evidence to back that up, there is no one formulation that has been accepted by all the OEMs.

While that question will be mulled over by regulators and engineers for some time, Eaton is realistic about the current state of the controversy. Yes, there is evidence in the lab that mixtures of more than 25% of one coolant technology with another will cause the resulting solution to fail the relevant standards, but it is more common that a failed coolant and any resulting damage will be the product of much less exotic problems, such as bad water or the wrong mix ratio.

This is particularly prevalent in heavy-duty and off-road applications (a point that was reinforced by panel members in the afternoon portion of the session), where roadside refills can either dilute the coolant package to near-water, or increase the concentration to the point that protection is compromised. (The ideal proportion is 50/50, but no more than 60/40, water/coolant).

Water quality is a huge variable. Chlorine will corrode aluminum tubes. Mineral-laden water will clog them. Sand and dirt, and silicate and inhibitor dropout from incorrect use of supplemental coolant additives (SCAs), also compromise cooling.

Together, these conditions have spurred Eaton to advise that coolant filters be used and changed regularly, and wherever very poor water is present, to use distilled water.

Also, in keeping with the real-world problems more commonly encountered, Eaton advised the use of some simple tools, and warned against the use of others.

“A refractometer is the best tool in your shop. I would prefer that you had one you could calibrate, but they are really great tools.”

Putting a drop of coolant on a refractometer only takes a few seconds, and can give early indications of trouble.

“Test strips are probably second-best, provided they are in good condition. They do measure nitrite and molybdinate, but you do need to know the coolant you are testing, as there are some without nitrite and molybdinate.” Professional lab kits are also a valuable addition. “But do not let anyone tell you that conductivity is a good way to test coolant quality. It is not.”

Beyond sound advice on how to retain confidence in the coolant in a system, and avoid unforeseeable trouble, he off
ered some simple advice on how to avoid the foreseeable.

“I’m suggesting that you stay with the coolant family of the OEM fill. If it had OAT, stick with OAT.

“At least until such time as there is more data on the variety of coolants’ effects on each other.”

Cool Enough For Ya?

Trouble with Cooling Diagnosis? Check the Obvious

“The cooling system and the a/c system are a set of interconnected systems and components, and the most important component of all is airflow. If airflow is compromised, you won’t get cool,” Mike Leeper of Hayden told Cooling and Coolant Track attendees. “Have you added an auxiliary fan, and now the car is overheating?”

He said that the first step in determining the cause of such problems is to conduct a temperature check, and then do a visual inspection to insure that all the ducting that should be there is still in place.

“One of the things that we never do is temperature testing. Temperature testing is huge. Proximity temperature probes are really no good. You need a touch probe to check a condenser. And you need to put the system under maximum load:

* Engine at operating temperatures

* Engine at idle

* A/C set on max. position

* Blower on high speed

* All the doors open.

Leeper said that something as seemingly innocuous as a suspension lift kit or drop kit can change airflow enough to affect cooling.

“It’s nice to put that lift kit on, but what the heck happened to the air dam?”

Much more of the cooling airflow comes from below a vehicle than traditionally, he said, something that may not be widely recognized.

“Air dams are not an option,” he insisted; in fact, they are required for proper cooling system function.

The same applies to ductwork around the radiator and condenser.

“That is the airbox’s integrity. If you take the foam off, your airflow is over the top of the radiator. When you do that your cooling goes to heck.”

And what about that initial question on how an auxiliary fan can actually reduce cooling?

“You start blowing cool air across the fan clutch, the clutch doesn’t engage, and the cooling suffers. It’s really amazing what happens. How do you fix it? Put a controller on it.”

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