DRAIN, REFILL & FLUSHING

Completely draining and refilling the cooling system every two years at least will remove accumulated rust, scale and other deposits. Coolant in late model trucks is a 50/50 mixture of ethylene glycol (make sure it is safe for aluminum components) and water for year round use. Use a good quality antifreeze with water pump lubricants, rust inhibitors and other corrosion inhibitors along with acid neutralizers.

1. Drain the existing antifreeze and coolant. It may be necessary to remove a splash shield, on some models, to gain access to the drain at the bottom of the radiator. Open the radiator and engine drain petcocks, or disconnect the bottom radiator hose, at the radiator outlet.

   CAUTION
   When draining the coolant, keep in mind that cats and dogs are attracted by the ethylene glycol antifreeze, and are quite likely to drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in sufficient quantity. Always drain the coolant into a sealable container. Coolant should be reused unless it is contaminated or several years old.

   NOTE: Before opening the radiator petcock, spray it with some penetrating lubricant.

2. Close the petcock or reconnect the lower hose and fill the system with water.
3. Add a can of quality radiator flush.

   Fig. 3: To refill the system with coolant, remove the radiator cap. NEVER remove the cap if the system is HOT

4. Idle the engine until the upper radiator hose gets hot.
5. Drain the system again.
6. Repeat this process until the drained water is clear and free of scale.
7. Close all petcocks and connect all the hoses.
8. If equipped with a coolant recovery system, flush the reservoir with water and leave empty.
9. Determine the capacity of your coolant system (see capacities specifications). Add a 50/50 mix of quality antifreeze (ethylene glycol) and water to provide the desired protection to the level of the radiator filler port. Fill the coolant reservoir to the correct level. Install the radiator cap.
10. Run the engine to operating temperature.
11. Stop the engine. Allow the engine to cool and check the coolant level in the radiator. Add more coolant if necessary to the radiator.

    Fig. 4: Cooling systems should be pressure tested for leaks periodically

12. Check the level of protection with an antifreeze tester, replace the cap and check for leaks.