Cooling system check

Warning: Wait until the engine is completely cool before beginning this procedure. Caution: Never mix green-colored ethylene glycol antifreeze and orange-colored DEXCOOL silicate-free coolant because doing so will destroy the efficiency of the DEX-COOL coolant, which is designed to last for 100,000 miles or five years.

1. Many major engine failures can be attributed to a faulty cooling system. The cooling system also cools the transmission fluid and thus plays an important role in prolonging transmission life.

2. The cooling system should be checked with the engine cold. Do this before the vehicle is driven for the day or after it has been shut off for at least three hours.

3. Remove the coolant pressure cap on the expansion tank by slowly unscrewing it. If you hear any hissing sounds (indicating there is still pressure in the system), wait until it stops. Thoroughly clean the cap, inside and out, with clean water. Also clean the filler neck on the expansion tank. All traces of corrosion should be removed. The coolant inside the expansion tank should be relatively transparent. If it is rust colored, the system should be drained and refilled (see Cooling system servicing (draining, flushing and refilling)). If the coolant level is not up to the Cold mark, add additional antifreeze/coolant mixture (see Fluid level checks).

4. Carefully check the large upper and lower radiator hoses along with any smaller diameter heater hoses that run from the engine to the firewall. Inspect each hose along its entire length, replacing any hose that is cracked, swollen or shows signs of deterioration. Cracks may become more apparent if the hose is squeezed (see illustration).

14.4 Hoses, like drivebelts, have a habit of failing at the worst possible time — to prevent the inconvenience of a blown radiator or heater hose, inspect them carefully as shown here

Check for a chafed area that could fail prematurely.

Check for a soft area indicating the hose has deteriorated inside.

Overtightening the clamp on a hardened hose will damage the hose and cause a leak.

Check each hose for swelling and oil-soaked ends. Cracks and breaks can be located by squeezing the hose.

5. Make sure all those connections are tight. A leak in the cooling system will usually show up as white or rust-colored deposits on the areas adjoining the leak. If wire-type clamps are used at the ends of the hoses, it may be wise to replace them with more secure, screw-type clamps.

6. Use compressed air or a soft brush to remove bugs, leaves, etc., from the front of the radiator or air conditioning condenser. Be careful not to damage the delicate cooling fins or cut yourself on them.

7. Every other inspection, or at the first indication of cooling system problems, have the cap and system pressure tested. If you don’t have a pressure tester, most gas stations and repair shops will do this for a minimal charge.

Overheat Protection Operating Mode

8. These engines have a system to protect the engine from damage caused by severe overheating. When the computer senses an overheat condition, an instrument panel warning light comes on that says «reduced power.» In this mode, the computer switches the firing of the individual coils on and off at each cylinder to allow cooling cycles between the firing cycles. The engine will have a dramatic loss of power, but will allow vehicle operation in an emergency.

9. If this light is on, find a safe place to get off the road as soon as possible, and allow the engine to cool thoroughly.

10. Check the coolant level and inspect for a split hose or other obvious signs of coolant leakage.

11. The engine oil will be ruined after this mode has operated, since unburned fuel will get into the oil. After fixing the overheating problem, change the oil and filter right away and reset the Oil Life Monitor (see Engine oil and filter change).

  • Pages

    open all | close all