A Science Experiment Under Your Hood

| May 03, 2005

Need-release filters can make conventional coolants as easy as ELCs.

Diesels that get regular cooling system care and oil and filter changes will rarely develop mechanical problems unless subjected to extreme driver abuse.

Your diesel’s cooling system is like a “science experiment,” says Garrett Funk, northeast regional manager for Penray, because of an interaction of metal, water, heat and oxygen with the acids formed in combustion.

Truck diesels have replaceable cylinder liners so they can be rebuilt easily. But those cylinder liners vibrate, which makes them vulnerable to pitting if the coolant is corrosive. Unprotected cylinder liners can develop pits that may end up creating a hole right through the metal, Funk says.

Traditional coolants use supplemental coolant additives (SCAs) containing nitrites for cylinder liner protection and other materials to protect the rest of the cooling system. The materials in the SCAs break down as they defend the metal surfaces, so they must be replaced continually. The rate of replacement is directly related to how hard the engine works.

Conventional coolants tolerate the addition of fresh antifreeze with many different types of corrosion protection systems. If diluted by additions of the wrong stuff, it can be easily restored without a complete change just by adding the right amount of SCAs.

The Extended Life Coolant system, introduced by ChevronTexaco and Caterpillar several years ago, is extremely reliable and straightforward, but it requires careful addition of only the right coolant. “ELC can tolerate up to 25 percent contamination,” says ChevronTexaco’s Carmen Ulabarro.

The cooling system is not a closed system, Funk says, but one subject to leakage and refilling by drivers using straight water or different types of antifreeze. This is why many fleets have continued to use the conventional system. We enlisted the help of Don Delaney, parts manager, and the other folks at the Penn Detroit Diesel-Allison distributor in Philadelphia to show us the procedure for proper conventional coolant maintenance.

Need-release filters
Supplemental Coolant Additives can be added from a bottle or by installing a coolant filter charged with them at appropriate maintenance intervals. But there is also a much easier way.

When ELC was introduced, Penray Company responded by developing a new coolant protection system called Fill for Life. The heart of the process is a special type of SCA-containing coolant filter called a need-release filter. This type of filter is marketed by Penray as the Penray Need-Release filter, and also by Detroit Diesel under its Power Cool brand. Need-release filters stay on for a long time – in the case of the Penray unit 150,000 miles or 15 months (or 3,000 hours if you do maintenance by hours rather than miles). They are also made by several other companies (see For Further Information).

The other half of the process is the exclusive use, both for initial fill and coolant additions, of fully-formulated antifreeze meeting TMC RP-329 TYPE A specifications, which has the right dose of SCAs already in it. A number of brands of this coolant are widely available. The system becomes almost as easy to maintain as ELC, provided only the correct coolant is added. And its life can be even longer.

The big advantage of the need-release filter is that it does the job of testing the system and dosing it as required, needing only occasional routine checks in case somebody has put in the wrong stuff. Its supply of SCAs is separated from the coolant by special membranes that allow the SCAs to pass into the system only as the system chemistry changes and requires more SCAs. While it may cost several times what a standard filter with SCAs costs ($50-$70), the overall cost per mile is actually lower, and the freedom from worry about the system is priceless.

Six-month checkup
In a perfect truck where no cooling system leaks ever occurred, you would only have to replace the need-release filter every 150,000 miles, 3,000 hours or 15 months (Detroit Diesel’s hours figure is 2,000). But coolant leaks out, and some types of coolant hoses may actually allow small amounts of water to be lost from the system, resulting in a higher antifreeze concentration. You need to check out the system every six months and compensate if these things happen. Remember that if only the right TMC RP-329 TYPE A coolant is added, this job will be much easier because you will only be adjusting the antifreeze level.

Comments are closed.

OverdriveOnline.com strives to maintain an open forum for reader opinions. Click here to read our comment policy.