A Science Experiment Under Your Hood

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.

Partner Insights
Information to advance your business from industry suppliers

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.

For the six-month check, purchase a bottle of coolant test strips, either the two-way Penray Fill For Life brand or three-way Detroit Diesel Power Trac brand. Carefully review the directions on the label, especially test conditions.

First collect a small amount of coolant in a clean container. It’s safest to allow the engine to cool first so you won’t run the risk of burning yourself. Draining some coolant from the cock in the bottom of the radiator into a bottle is probably the easiest way to collect your sample.

If the coolant is very hot or cold, allow it to come close to room temperature. Test conditions require coolant between 50 degrees and 130 degrees F, so the strips will give accurate readings.

How to read the Detroit Diesel Power Trac 3-way strips:

  1. Dip the strip so all three pads are covered for one full second. Then pull the strip out and lightly flick excess coolant off into a catch pan. Note the position of the second hand on your watch.
  2. Wait 15 seconds for the top pad’s color to stabilize. Then hold the top pad next to the row of color samples that show antifreeze percentage. Note the percent glycol number next to the pad that has the color closest to the color of the strip pad.
  3. After 45 seconds, compare the color of the second or middle pad to the single colored sample on the bottle indicating the overall additive concentration.

How to read the Penray 2-way strips:

  1. Dip the strip so both pads are covered for two full seconds. Then pull the strip out and lightly flick excess coolant off into a catch pan. Note the position of the second hand on your watch.
  2. After 45 seconds, compare the freeze point or upper pad to the row of freeze point sample colors on the upper row on the side of the bottle, and note the percentage.
  3. Right away, compare the color of the lower pad on the strip to the row of sample colors for nitrite concentration. Note the nitrite concentration in ppm. The ideal number is 1,200 ppm.

For both types of test strips, using a refractometer is the most precise way to read antifreeze concentration. If you have one, you may want to use it to get a more precise reading, especially if the color of the appropriate pad on the strip is right between two of the sample colors.

To use the refractometer, open up the hinged plastic cover over the light window, and then use the eyedropper supplied to get a few drops of coolant from your collection pan. Squeeze a few drops of the coolant onto the window, and then close the cover. Hold the window end of the unit toward a source of light and peer into the eyepiece. A dark line will run right across the scale and allow you to read the antifreeze concentration.

Keeping a balance
Once you know what the antifreeze concentration is, you should adjust it if necessary. The ideal concentration is 50/50 unless you live in an area where the level of protection a 50/50 mix provides, which is -34 degrees F, is not adequate. If necessary, you can use up to 60 percent concentration, which protects down to -65 degrees.

Don’t go outside this range. Using more than 60 percent will prevent the cooling system from carrying heat away from the engine’s metal parts the way it should. Using less will compromise freezing and boiling protection (allowing your cooling system to boil over too easily), and corrosion protection.

To increase the concentration, you’ll need to add straight antifreeze. To decrease it, you’ll have to add de-ionized water. You could actually use tap water from your area, provided you’ve had it tested by your antifreeze supplier and approved for use in your cooling system. Otherwise, buy de-ionized water and use that only. This is necessary because water with minerals in it will cause the SCAs to form a grit that can ruin water pump seals. They may also fail to dissolve properly and protect the system.

Once you know what the concentration is, unless it’s close to 50/50 or your desired level of freeze protection, refer to a chart like the one provided by Penray. The chart will show antifreeze concentration by percentages across the top. Each line, labeled on the left, represents a different cooling system capacity in gallons, from five to 20.

  1. Look up the cooling system capacity in the owner’s manual in gallons. Then find the line representing the number of gallons corresponding to that capacity in the chart in the left hand column. Once you have found the correct line, follow it over to the right until you’ve found the percentage of coolant you got reading the strip or the refractometer (listed along the top). Below that percentage, in the line representing the capacity for your system, will be the amount of water or antifreeze in quarts you’ll have to add to correct the concentration. The numbers to the left of center are the quarts of antifreeze you need to add. The numbers to the right of center are the quarts of water you have to add. Once you’ve found the number of quarts of water or antifreeze to add, drain that much out of the system and add the amount indicated.
  2. If your need-release filter is working, and you have been adding only the proper coolant, the color of the protection level patch should match (Detroit Diesel Power Trac only). Also, the nitrite level should be well within the approved range, which is 800-2,400 ppm. In fact, it should be very close to the ideal of 1,200 ppm. If below 800 ppm, somebody has probably been adding plain antifreeze or water. If that happens, purchase a container of Penncool 3000 or Detroit Diesel Powercool 3000. Follow the directions on the test strip container right below the sample color patch that matched the color of the strip. Based on the capacity of your cooling system and the nitrite concentration in ppm, they will tell you how much SCA liquid to add. For example, when using the Penray supplies, if the concentration is 400 ppm, you add 1 pint for each 8 gallons of system capacity. Drain enough coolant out to add the correct amount of SCA concentration and then do so.
  3. If using a need-release filter, the only way the system will have too much in the way of nitrites is if someone has been overdosing it by adding them when they are not needed. In the rare case when the coolant does have too high a concentration of nitrites, you’ll need to drain out a few gallons of antifreeze and add plain antifreeze-deionized mix that has no SCAs or the proper TMC RP-329 TYPE A coolant, mixed with deionized water. Some overdosing is OK because if you stop adding SCAs, the level will diminish as you drive. Detroit Diesel recommends diluting them when the concentration passes 4,000 ppm. You drain half your antifreeze, refill and retest. Penray says the problem isn’t critical until the concentration passes 6,000 ppm. If your reading is in that range, Penray suggests you completely drain and refill with the right coolant, then retest.
  4. Once the adjustment has been made, run the system for a few minutes to distribute the SCAs or plain antifreeze and then retest. Readjust if necessary in the same way.
  5. Check the date, mileage and hours written on the need-release filter. If the filter is due for a change, change it as described below. A filter overdue for a change can contribute to a low nitrite or overall protection level.
  6. To change the filter, make sure the engine has been stopped for a while and allowed to cool. Cautiously release the radiator cap to make sure there is no pressure in the system. Get a catch pan and place it under the coolant filter.
  7. Position a strap wrench of appropriate size around the filter so it will grab if turned counter-clockwise as viewed from below. Then use the wrench to loosen the filter. Once it can be turned easily, turn and remove it with your hand.
  8. Thoroughly wipe down the coolant filter mount with a clean rag.
  9. Unwrap the new filter. Look up the miles or hours on the vehicle on the dashboard. Write the date and miles or hours on the filter housing in the area provided for that purpose (the black Penray filter has a white area for those numbers). Then coat the entire top surface of the rubber gasket with clean engine oil or white grease. Be careful not to get oil inside the filter.
  10. Read and take note of the tightening instructions on the new filter. Carefully start it onto the threads on the coolant filter mount by holding it as vertical as you can and turning gently. Once it turns easily on the threads, tighten by hand until the gasket just contacts the mounting. Then reverse the strap wrench and turn the additional number of turns specified.
  11. Refill the cooling system with TMC RP-329 TYPE A coolant only and replace the radiator cap. Run the engine until the thermostat opens. Stop the engine, carefully remove the cap and top off the system as necessary.
  12. If your coolant nitrite concentration was incorrect, take appropriate measures to make sure only the correct TMC RP-329 TYPE A coolant is added and that nobody, including a service shop that may do oil changes for you, adds regular coolant or SCAs or attempts to replace the need-release filter with a standard coolant filter.

Penray’s Funk says it’s also a good idea to send your coolant to a test lab for analysis every one to two years. This will warn you if any serious problems are developing or if something has gone wrong in your testing. This would also be advisable if using ELC and there is any chance it may have been diluted with the wrong type of coolant.

For further information, please contact the following:
(925) 842-1000

Caterpillar Engine Div.
(309) 675-1000
www.caterpillar.com, click engines

Shell Oil Co. U.S.
713 241-6161

Detroit Diesel Corp.
(313) 592-5000

Fleetguard, Inc.
(615) 367-0040

The Penray Companies
(800) 322-2143

(602) 252-0280
(Amalgatech does coolant analysis.)

Showcase your workhorse
Add a photo of your rig to our Reader Rigs collection to share it with your peers and the world. Tell us the story behind the truck and your business to help build its story.
Submit Your Rig
Reader Rig Submission