See Figures 1 and 2
At least once every 2 years, the engine cooling system should be inspected, flushed, and refilled with fresh coolant. If the coolant is left in the system too long, it loses its ability to prevent rust and corrosion. If the coolant has been diluted with too much water, it won't protect against freezing.
The radiator 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 Belt Tension Adjustment).
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. This must be corrected before filling the system with fresh coolant.
CHECK THE RADIATOR CAP
See Figures 3, 4, 5, 6 and 7
While you are checking the coolant level, check the radiator cap for a worn or cracked gasket. If the cap doesn't seal properly, fluid will be lost in the form of steam and the engine will overheat. Replace the cap with a new one, if necessary.
CLEAN RADIATOR OF DEBRIS
See Figure 8
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 & REFILL
See Figures 9 and 10
Completely draining and refilling the cooling system every two years at least will remove the accumulated rust, scale and other deposits. Coolant in late model vans 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.
- Remove the radiator cap. Drain the existing coolant by opening the radiator and engine drain petcocks, or disconnecting the bottom radiator hose at the radiator outlet.
Before opening the radiator petcock, spray it with some penetrating lubricant.
- Close the petcock or re-connect the lower hose and fill the system with water.
- Add a can of quality radiator flush.
- 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 cooling system (see the Capacities 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.