Coolant and Your Country Coach Cooling System – Part 1

A Look at Coolant and Your Country Coach Cooling System – Part 1

by James Sonntag, CC owner, a retired engineer from a major oil company, and printed with permission

* Mr. Sonntag wrote this article back in 2004. Recently when I contacted him regarding sharing his article with my Country Coach Friends, he agreed reprint of the original article, with this one request: Some things may have changed over the years and so it would be good to have someone give the article a good read-through with an eye to what might need an additional note added to give more current information. Country Coach Corporation’s David Diamond and Doug Beaudry (www.countrycoach.com) provided a review of the article as originally written.  I appreciate their attention to the article and am happy to share Part 1 of Mr. Sonntag’s article here. The rest of the article will follow soon.

Maintenance of engine coolant is often neglected until an engine problem causes a breakdown and interrupts your vacation. Although you might think that neglect leads only to engine coolant overheating, one coolant manufacturer claims that 40% of all engine problems can be traced to improper coolant maintenance. Please be aware that maintaining the engine’s coolant quality is of equal importance to maintaining the engine’s lubricating oil quality and the engine’s fuel quality.

This article will tell you what you need to know about coolants and what you need to do to properly maintain your Country Coach cooling system (pre-2005 model year). (Recommendations apply to both the main engine and the Onan generator.) Also discussed is the special heat transfer fluid used in the Hydro-Hot Hydronic Heat systems.

What is Coolant?

The liquid in the engine radiator is called “engine coolant” if it is composed of three things:

1)  Water (about 47%)

The best water for coolant is either distilled or de-ionized. It must not contain high mineral concentrations, particularly calcium or magnesium, which can react with coolant additives to form sediment and scale.

The worst possible water is that which has been “softened.” Softened water is typically made by substituting the sodium for the calcium in the water. Sodium (salt) is corrosive to all metals. Never use “softened” water in your cooling system.

2)  Glycol (about 50%)

Often called “antifreeze,” Glycol provides freeze protection by lowering the freezing point of a glycol/water mixture, and also acts to increase the boiling point of a glycol/water mixture. Both actions are beneficial for coolant.

The most commonly used glycol is ethylene glycol (“EG”). This has been the predominant glycol in antifreeze for many years. However EG, when ingested, is toxic to humans and animals.

In recent years a more environmentally friendly glycol, propylene glycol (“PG”), has gained favor. Pure PG is generally regarded as safe by the FDA. A PG-based antifreeze reduces the risk of poisoning the environment. (But don’t drink PG coolant! Coolant contains additive which are harmful if swallowed!)

Note that products sold as “antifreeze” are often a concentrate. Before use, concentrates must be diluted with equal parts of water, which should be either distilled or de-ionized.

3)  Additives (about 3%)

These act to protect the engine cooling system from rust and corrosion, scale and mineral deposits, foaming, cavitation, and pitting of the cylinder-bore liner where it is exposed to the coolant.

The additive package used in coolant designed for gasoline engines is not formulated to protect heavy-duty diesel engines. In particular, it fails to protect against cavitation and pitting of the cylinder-bore liner.

If all the necessary additives for heavy-duty diesel engine service are in the coolant, the coolant is called “fully formulated.” Some coolants are only “partially formulated” because they may also be used in other applications. Partially formulated coolants require the addition of supplemental coolant additive (SCA) – also known as diesel coolant additive (DCA) – to make them fully formulated before the coolant is used in heavy-duty diesel engines.

Additives in coolant will wear down from normal use, thereby depleting their concentrations. Additive concentrations can also be reduced by topping off the cooling system with water causing undesirable dilution, and a loose radiator cap or a low coolant level in the surge tank will reduce the coolant additives through oxidation. Because additives wear down and because additives can be diluted through improper maintenance, additive concentrations must be monitored throughout the life of the coolant. When tests show additive concentrations are low, additives must be replenished or the cooling system will be susceptible to damage.

On the other hand, an over-concentration of additives will also harm the cooling system. Over-concentrated additives will “drop out” of the coolant, forming a sludge or gel which can block radiator tubes and/or settle in the bottom of the cylinder block.

Coolant types and their identification

Coolants come in a rainbow of colors. You can find green, blue, purple, pink, and red to name a few. Unfortunately no commercial standard has been adopted for each color’s meaning. Matching colors will not guarantee a match of coolant types even if the coolant is from the same manufacturer.

Fortunately there are only four basic types of coolants in use. To properly identify each type, you need to closely read the label on the coolant’s container. The identification is made by noting the testing standards which the coolant meets or exceeds.

Coolant testing standards are primarily set by two organizations. The first is the American Society of Testing and Materials (ASTM). The second is the Technology and Maintenance Council of American Trucking Association, which issues “recommended practices” (abbreviated RP or TMC RP). If there is no statement on the container which begins, “meets or exceeds ASTM,” and/or “meets or exceeds RP,” then look for another coolant brand.

The four types of coolant are:

1)  “Automatic Antifreeze and Coolants”

Designed for use in passenger cars and light-duty trucks, these are characterized as “meeting ASTM specifications D-3306” and/or major auto makers’ testing standards, but none of the testing standards for heavy duty coolants. This type should never be used in a heavy-duty diesel engine.

2)  “Heavy Duty, Partially Formulated Coolant”

Also known as “Heavy Duty, Low Silicate Antifreeze” to which supplemental coolant additive, or SCA, must be added before use as a diesel engine coolant. These are characterized as “meeting ASTM specification D-4985.” Although this partially formulated coolant type is becoming obsolete, it is the “conventional” type of coolant that has been used in heavy-duty diesel engines for many years.

The SCA charge may be added as a liquid, as a tablet, or as contained within an engine coolant filter. The amount is determined by the coolant and/or engine manufacturer’s recommendation, typically based on the capacity of the cooling system.

During the life of the coolant, the SCA concentration levels need to be frequently monitored, with lost SCA replenished on a “test-to-add” basis. Testing is typically done with “test strips” available from the coolant manufacturer which are dipped into a sample of the coolant. The resulting color of the strip is compared to a color table to determine the result. Test results and manufacturers instructions determine the amount of SCA to add.

Testing is typically done at each oil change or every six months, whichever comes first. If needed, additional SCA is added either by using a liquid SCA, or by using a new coolant filter containing SCA. Note that if liquid SCA is used, the coolant filter should be “chemically free.” Typical service live of this coolant is two years.

3).“Heavy Duty, Fully Formulated Coolant”

This coolant type is ready to use right out of the container as it is pre-charged with SCA. It is characterized as “meeting ASTM specifications D6210 plus TMC specifications RP-329 (for EG); or ASTM D-6211 plus TMC specifications RP-330 (for PG).”

Recently specification D-6211 for PG was withdrawn and subsequently incorporated into ASTM specifications D-6210. Future packaging for PG coolant will read as meeting specification ASTM D-6210 plus TMC specifications RP-330.

Fully formulated coolants also require monitoring of SCA concentration levels. Lost SCA is replenished on a “test-to-add” basis, in the same manner as partially formulated coolants. Typically the test is performed at each oil change or every six months, whichever comes first.

Typical service life of this coolant type is two years. However, the life of this coolant type may be significantly extended by replenishing lost additives with an Extended Service Additive (ESA) instead of a “conventional SCA.” An ESA is similar to a conventional SCA in chemical make-up. The difference is that an ESA is specifically formulated to replenish depleted coolant additives based on their relative depletion rates. Replenishing additives using an ESA (versus a conventional SCA) minimizes the over-concentration of additives which are slowest to deplete, thereby extending coolant life.

Not all coolant manufacturers offer an ESA for this coolant type. However, when available, the use of an ESA is a better choice than the use of a conventional SCA. Check the product listing of your coolant manufacturer to see if an ESA is available for your specific coolant. Also check for the procedural steps to add an ESA to your coolant in place of an SCA as they may be different. ESA is available in a liquid form and also as a “need release” filter.  If the liquid form of ESA is to be used. Select a coolant filter which is “chemically free.”

4)  “Heavy Duty, Fully Formulated, Extended Service Interval Coolant’

     This coolant type is also ready to use right out of the container as it is pre-charged with SCA. It uses a different chemical coolant. The formulation is based on an “organic acid technology” abbreviated as OAT. The OAT advantage is a much slower rate of additive depletion versus conventional additives of non-organic acids.

     Extended service interval coolants can be found in two forms, depending on how much organic acid is used. Where the additive package is a mixture of conventional additives and OAT additives, the coolant is called “Hybrid.” Where the additives are 70% to 90% organic acids the coolant is simply called “OAT.”

A) Hybrid, Heavy Duty, Fully Formulated, Extended Service Interval Coolant”

     This coolant type is characterized as meeting the same ASTM and RP specifications as the “Heavy-Duty, Fully Formulated Coolant, Pre-charged with SCA,” listed above AND as meeting RP-338, the “extended Service Interval Coolant” specification. This coolant also meets Cummins Engineering Standard CES-14603.

     SCA testing must be performed at least twice per year. To replenish additives, use only an ESA (never a conventional SCA). Typically the ESA is added once per year. The amount of ESA will be based on test results and the coolant manufacturer’s recommendation. Additive replenishment may be done by either liquid ESA or by “ESA need release” coolant filters.

     Properly maintained, this coolant is designed to last until either testing or visual inspection shows that condemning limits have been reached. This is estimated to be four to six years.

B)  OAT, Heavy Duty, Fully Formulated, Extended Service Interval Coolant

     This coolant type is the newest available formulation. It is not yet uniquely defined by ASTM or RP specifications, but rather by specifications from the major diesel engine manufacturers.

          Detroit Diesel: 7SE298 9804

          Caterpillar: EC-1

          Cummins: CES4603

     OAT coolant manufacturers indicate that there is no need for periodic SCA testing. However, after two to three years of service (depending on the coolant manufacturer), the only additive ever needed is a liquid “extender,” or a new need-release coolant filter.

     Properly maintained, this coolant need not be changed until it reaches the end of its estimated 4- to 6-years service life, or until it will not pass visual inspection for contaminants.

     Note, however, that if this coolant is diluted by other coolant types, the extended life properties will be lost and the coolant will have only a two year life.

To Be Continued in Part 2 which addresses Maintaining Coolants, Hydro-Hot and other information.