Coolant Problems in 2007-2008 Diesel Engines

The 2007 and 2008 medium and heavy duty engines with the new emissions devices are creating new and potentially serious problems for cooling systems in general and coolants in particular.

With cooling loads increased by as much as 30% over the previous engines we are seeing issues that must be understood and addressed by users.

As trucks have become more aerodynamic the underhood area has been reduced and airflows restricted. At the same time we have larger displacement engines often with higher horsepower density, plus EGR systems recirculating greater volumes of very hot air together with other heat producing, exhaust restricting Emissions devices.

We have seen trucks with fiberglass hoods that have warped or melted from this tremendous heat load.

All of this places more heat into the coolant, and not only more heat, but higher average temperatures.

Many of today’s coolants are excellent products, however they need more monitoring and more maintenance than ever before.

In the past many fleet experts and OEM’s would recommend an annual check of the coolant. Today these high loads can use up the additive package found in coolants in weeks rather than months. We have seen instances where coolant is properly checked and found to be in good condition, yet in less than a month it can be worthless.

We have seen coolant actually turn black, not from contamination, but simply from continuous high heat loads. Silicate drop out and gelling is more prevalent than ever before.

When this coolant begins to deteriorate the cooling system can be damaged very quickly. We are seeing radiators and heater cores that the solder has been eaten away by the coolant. We are seeing far more liner and even block cavitation problems than ever before.

As a result we have some suggestion and recommendations to try and protect your engines and cooling systems.

1. Check coolant with fresh Test Strips or Refractometer at every oil change or quarterly, whichever comes first. (Note: Old test strips can give inaccurate readings)

2. Use only fully formulated coolants from reputable sources for top-offs, and replacement. There is now a huge problem where some suppliers are purchasing used ethylene glycol from manufacturers that had used it in the manufacture of made-made fabrics. They then try to filter out the contaminants and then they use substandard additive packages to make what they claim is new antifreeze from virgin product. This is usually a poor to very poor quality product. It will look ok and a level 1 or 2 test might not show a problem. However a level 3 or 4 test done by a reputable lab will show real and potentially damaging problems.

3. Never top-off with just water. Coolant works best at a 50%-50% to 50%-70% mix. If it gets out of spec, it will not work properly, and can actually cause expensive damage.

4. In our opinion all diesel engines in medium and heavy duty applications should have coolant filters.

5. If you decide that have buy concentrate and mix it yourself, get a mixing system and install either a de-ionizing system for the water or use distilled water. Contaminants in some tap water can render the coolant useless. (See item 2)

6. You should use only the coolant recommended by the OEM. Do not mix antifreeze colors, especially do not mix OA (orange) and OAC (red) with any other color.

7. If you have a failure where oil gets in the cooling system or where you have silicate drop-out or silicate gelling, you need to flush the system with an acid type cleaner and neutralizing agent. If you don’t spend the time to do this procedure, you will have continuing cooling system problems.

8. Use SCA additive as required such as Enertech Labs – ETL 1000. This is a high quality additive package to bring your system up to the OEM specification.

9. If you have a problem where you need to make the same repair over and over, get some help. Many of the old rules don’t apply anymore.

10. The 2010 engines are likely to be even hotter, get ready.

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Last modified: 09/01/08