A coolant change will ready your truck for thousands more miles without overheating or radiator trouble

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There are two types of truck diesel engine coolant out there these days: extended life coolant (ELC) and fully formulated antifreeze, to which you add supplemental coolant additives (SCAs) as needed. Regardless of which you use, your coolant eventually will need to be changed. With ELC, it’s necessary to replenish the carboxylates. These protect the system from corrosion and eventually begin to deteriorate. With other coolants, a change is needed to remove acids or solids that build up in the coolant and can’t be removed on the truck.

Consult the literature your supplier provides to determine when it’s time to change. The interval is normally from about 600,000-1,000,000 miles. You also can get your coolant lab-tested periodically and let the lab tell you when to change.

To collect the coolant, get a good-size drain pan and make sure you have a place to store the old antifreeze for proper disposal – perhaps some used antifreeze jugs. Coolant capacity for a heavy-duty diesel is normally about 12 gallons.

Also, make sure you have a basic set of open-end or box wrenches as well as some sealer designed for cooling systems. Get a radiator cap tester if you don’t have one already. And, unless you plan to use 50/50 pre-mixed coolant, get a refractometer or coolant strength test strips.

Throughout the process, make sure to get the engine full of water or coolant before operating it and that you shut it down before draining.

The Job
Drain the system. To prevent scalding yourself when you remove the radiator cap, shut the engine off and allow it to cool until it’s at about 160 degrees F. Set the parking brake, chock the wheels and make sure the transmission is in neutral and the two valves to the heater are open (A).