Toyota RAV4 > Tune-up and routine maintenance > Cooling system check

Cooling system check

1. Many major engine failures can be attributed to a faulty cooling system. If the vehicle is equipped with an automatic transaxle, the cooling system also cools the transaxle fluid and thus plays an important role in prolonging transaxle life.

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

Warning: Never remove the cooling system pressure cap when the engine is running or has just been shut down, because the cooling system is hot. Escaping steam and scalding liquid could cause serious injury. Wait until the engine has cooled completely.

3. Slowly unscrew the pressure cap from the expansion tank. If you hear a hissing sound (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 opening on the expansion tank. All traces of corrosion or residue should be removed. The coolant inside the expansion tank should be relatively transparent. If not, the system should be drained and refilled (see Cooling system servicing (draining, flushing and refilling) ). If the coolant level isn’t up to the top, add additional antifreeze/coolant mixture (see Fluid level checks ).

4. Carefully check the large upper and lower radiator hoses along with the smaller diameter heater hoses which run from the engine to the firewall. Inspect each hose along its entire length, replacing any hose which is cracked, swollen or shows signs of deterioration. Cracks may become more apparent if the hose is squeezed (see illustration). Regardless of condition, it’s a good idea to replace hoses with new ones every two years.

i. 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 that 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 a good idea 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.

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