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Antifreeze Coolant For Truck Engines - Your Engine's Other Lifeblood

Posted in How To: Engine on November 1, 2009
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As The Turtle Expedition made final preparations for our Trans-Siberian Expedition, we knew we would be driving and camping in temperatures below -85 degrees Fahrenheit. That's 117 degrees below freezing. We needed to learn a little more about antifreeze. Something that could protect us in lower than the typical 20 degrees most of us prepare for.

Keeping your coolant in top condition is as important as checking your oil. The Polaris Labs test kit includes a sample bottle.

We contacted Cummins Filtration, makers of Fleetguard ES Compleat Lifetime Heavy Duty Fully Formulated Antifreeze/Coolant. We liked the fact that it used the environmentally-friendly propylene glycol, and the term "Lifetime Heavy Duty" had a nice ring to it. Our education in coolant was just beginning.

As is often said, oil is the lifeblood of engines. In fact, it's so important, we can sometimes forget about the other lifeblood, coolant. Coolant is critical to the proper function of any engine, especially diesels. The new engines introduced by manufacturers in the last few years are designed to lower fuel consumption and meet impending federal emissions laws. As a result, the cooling systems for these new designs must operate at much higher temperatures, making careful cooling system maintenance necessary to avoid engine damage due to boiling, deposits, or pitting. Improper mixtures of antifreeze can cause corrosion, rust, overheating, and even cylinder wall cavitation, which can turn into little pinholes-and that's an engine's death sentence.

The proper mixture of water to antifreeze (50/50 is recommended as a general starting point) doesn't only protect the engine from freezing. It also lowers the boiling point. That's very important in today's high-tech motors, with radiators sometimes blocked by aftermarket bumpers, jacks, shovels, winches, and lights.

There are two types of antifreeze commonly available: Propylene glycol and ethylene glycol. Ethylene glycol is considered to be highly toxic, and is poisonous. Its alternative, propylene glycol, is a colorless, odorless liquid, which is generally recognized as safe by the U.S. Food and Drug Administration. In addition to its use in antifreeze, coolants, and aircraft de-icing fluids, it is also used in foods, fragrances, cosmetics, and personal care products.

A turkey baster is an easy way to extract a sample of coolant from your radiator for lab analysis.

Propylene glycol is slightly less effective at lowering the freezing point though, so a little higher concentration must be used in extreme locations like Alaska or Siberia. However, for normal use it has a higher heat transfer efficiency. That's an advantage when you're lugging up a long, hot trail in low-range, or pulling a trailer over a pass where the signs warn, "Turn air conditioner off-next 8 miles."

By now, you should be wondering how you can tell what's in your cooling system. There are three important ways you can test. A refractometer can be used to determine the freezing point protection for ethylene glycol and propylene glycol. By placing a drop of your coolant on the refractometer's viewing plate, (after first calibrating it with distilled water and using the internal scale), you can calculate the freezing temperature. For example, a 52-percent concentration of propylene glycol will bring your protection point down to minus-50 degrees F.

Specifically for diesel engines, there is a danger of cylinder cavitation or pitting. According to, this is a localized low-pressure zone that forms adjacent to the outer wall of the cylinder. It is caused by the flexing of the cylinder wall due to the high cylinder pressures experienced in diesel engine ignition. This fast cylinder wall movement causes a low-pressure zone to be created in the coolant adjacent to the cylinder wall. When this pressure zone drops below the vapor pressure point (temperature, coolant ratio, and additive dependant), a vapor bubble is formed. When this low-pressure zone returns to a high-pressure state, the vapor bubble collapses, causing an implosion, or pitting phenomena on the cylinder wall (like hitting the surface with a microscopic ball-peen hammer). If left unchecked, it will eventually eat all the way through the cylinder wall.

To prevent cavitation, a diesel engine's coolant should be checked at regular intervals with a test kit such as the Fleetguard CC2607 QuikChek or the Polaris Labs four-part test strips. By simply dipping one of these test strips into your coolant and reading the chart, it will tell you the freezing point and the concentration of molybdate and nitrite, which in turn will determine the number of Supplemental Coolant Additive (SCA) units per gallon in the system. The Polaris strips also measure pH levels. With this knowledge, you can add the appropriate amount of additive, antifreeze, or distilled water to bring the coolant back up to a safe level. Fleetguard's DCA4 additive protects against corrosion, scale formation, foam, liner pitting, and solder bloom.

A third method of testing, and perhaps the best, is to have your coolant analyzed by a professional lab. We recently sent a sample from two of our expedition diesel trucks to Herguth Laboratories. The results were very informative.

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Both engines had been recently checked, and appropriate amounts of Fleetguard's DCA4 were added. The Ford F-550, a.k.a. The Turtle V, had been driven several thousand miles, while The Turtle IV had remained in storage. The cooling system in The Turtle IV was well inside the normal range in the main categories; SCA unit/gal, nitrite ppm, pH, and glycol. Aluminum was a little high at 7.7, which could be the result of having the radiator re-cored when we installed the new Franklin Power engine.

The analysis of The Turtle V's Power Stroke system showed a level of SCA of 3.8 units per gallon, a little high. Technicians at Polaris Labs told us that we should be under 3.2 units per gallon. Nitrite was right at the maximum level of 3,200 ppm. Glycol was a little low at 46.5 percent, which indicated that we could add a little propylene glycol concentrate, and that will lower the SCA level at the same time. Had the glycol level been too high, like 60 percent, we would need to add some distilled water to bring it down. Too high a concentrate of antifreeze can lower the boiling point of the coolant.

Aluminum was a tad high at 6 ppm (parts per million), but well below the maximum of 10 ppm. Polaris Labs technicians said it could indicate a little internal corrosion, but nothing serious. Aluminum is a very soft metal, and in the case of The Turtle V, with its Tortuga Expedition Camper, the coolant also runs back through a Seaward marine hot-water heater and a Hunter air-exchange heater, so the trace of aluminum may not be engine-related.

Having your coolant analyzed by a professional lab can alert you to easily correctable problems. It's sort of like going to the doctor to have a blood panel done. High cholesterol? Just add a few units of Fleetguard's DCA4, or maybe Lipitor might work better. More serious results could suggest a full transfusion (radiator drain and flush) with a quality 50/50 mix of propylene glycol.

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