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 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.
Additionally, whenever servicing the cooling system, the pressure cap should be looked at for signs of age or deterioration. Fan belt and other drive belts should be inspected and adjusted to the proper tension. (See checking belt tension).
Hose clamps should be tightened, and soft or cracked hoses replaced. Damp spots, or accumulations of rust or dye near hoses, water pump or other areas, indicate possible leakage, which must be corrected before filling the system with fresh coolant.
See Figure 1
- Allow the engine to cool and remove the radiator cap. Because a coolant recovery (overflow) tank is used, the coolant level should be at the cap seal in the filler neck. The coolant should be clear green or clear blue in color (depending on the brand of coolant used).
Examine the fluid color:
If the coolant is a very light green or blue, there is less than a 50/50 mixture and the system should be drained and refilled.
- Assuming the coolant is normal, add fluid as necessary.
While you are checking the coolant level, check the radiator cap for a worn or cracked gasket. It the cap doesn't seal properly, fluid will be lost and the engine will overheat. Worn caps should be replaced with a new one of the same presure rating.
CLEAN RADIATOR OF DEBRIS
See Figure 2
Periodically clean any debris-leaves, paper, insects, etc.-from the radiator fins. Pick the large pieces off by hand. The smaller pieces can be washed away with water pressure from a hose.
Carefully straighten any bent radiator fins with a pair of needle nose pliers. Be careful-the fins are very soft. Don't wiggle the fins back and forth too much. Straighten them once and try not to move them again.
DRAIN AND REFILL THE COOLING SYSTEM
See Figures 3, 4, 5, 6, 7, 8 and 9
- Drain the existing antifreeze coolant. Open the radiator petcock and remove the engine drain plugs, or disconnect the bottom radiator hose, at the radiator outlet.
Before opening the radiator petcock, spray it with some penetrating lubricant.
- Close the petcock or reconnect the lower hose and fill the system with water.
- Add a can of quality radiator flush.
- Place the heater control in the HOT position.
- Idle the engine until the upper radiator hose gets hot.
- Drain the system again.
- Repeat this process until the drained water is clear and free of scale.
- Close all petcocks and connect all the hoses.
- If equipped with a coolant recovery system, flush the reservoir with water and leave empty.
- Determine the capacity of your coolant system (see the Capacities specification chart). Add a 50/50 mix of quality antifreeze (ethylene glycol) and water to provide the desired protection.
- Run the engine to operating temperature.
- Stop the engine and check the coolant level.
- Check the level of protection with an antifreeze tester, replace the cap and check for leaks.