Toyota Previa 1991-1997 Repair Information

Cooling System



The correct coolant is any permanent, high quality ethylene glycol antifreeze mixed in a 50/50 concentration with water. This mixture gives the best combination of antifreeze and anti-boil characteristics within the engine.


See Figure 1

Always allow the van to sit and cool for an hour or so (longer is better) before removing the reservoir tank cap. To avoid injury when working on a warm engine, cover the reservoir tank cap with a thick cloth and turn it slowly counterclockwise until the pressure begins to escape. After the pressure is completely removed, remove the cap. Never remove the cap until the pressure is gone. There should be no excessive rust deposits around the cap or tank filler hole. The coolant should be free from any oil. On a COLD engine, place your finger in the coolant and check for oil or rust deposits.

Click image to see an enlarged view

Fig. Fig. 1: Check the levels on the reservoir tank for fluid capacity

It's best to check the coolant level when the engine is COLD. The radiator coolant level should be between the LOW and the FULL lines on the reservoir tank when the engine is cold. If low, check for leakage and add coolant up to the FULL line but do not overfill.

Check the freeze protection rating of the antifreeze at least once a year or as necessary with a suitable antifreeze tester.


See Figures 2 through 6

  1. Draining the cooling system is always done with the engine COLD .
  3. Remove the reservoir tank cap.

  1. Position the drain pan under the draincock on the bottom of the radiator. Additionally, some engines have a draincock on the side of the engine block, near the oil filter. This should be opened to aid in draining the cooling system completely. If for some reason the radiator draincock can't be used, you can loosen and remove the lower radiator hose at its joint to the radiator.

Click image to see an enlarged view

Fig. Fig. 2: View of the draincock locations

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.

Click image to see an enlarged view

Fig. Fig. 3: Always turn the draincock counterclockwise when loosening it

Click image to see an enlarged view

Fig. Fig. 4: Use a socket and extension to loosen the draincock in the engine block

  1. When the system stops draining, close both draincocks as necessary.
  3. Using a funnel if necessary, fill the reservoir tank with a 50/50 solution of antifreeze and water. Allow time for the fluid to run through the hoses and into the engine.
  5. Start the engine and let it idle about 10 minuets; add the coolant/water mixture up to the FULL level.
  7. Tighten the cap.
  9. Race the engine 2000-3000 rpms for about 5 minutes, then stop the engine.
  11. After the coolant drops, remove the cap and add coolant to the FULL level again.

Click image to see an enlarged view

Fig. Fig. 5: Check the level in the reservoir

  1. Securely tighten the cap again, then start the engine and check the level.

Click image to see an enlarged view

Fig. Fig. 6: Use a funnel to fill the coolant reservoir


Proceed with draining the system as outlined above. When the system has drained, reconnect any hoses close to the radiator draincock. Move the temperature control for the heater to its hottest position; this allows the heater core to be flushed as well. Using a garden hose or bucket, fill the reservoir and allow the water to run out the engine drain cock. Continue until the water runs clear. Be sure to clean the expansion tank as well.

If the system is badly contaminated with rust or scale, you can use a commercial flushing solution to clean it out. Follow the manufacturer's instructions. Some causes of rust are air in the system, failure to change the coolant regularly, use of excessively hard or soft water, and/or failure to use the correct mix of antifreeze and water.

After the system has been flushed, continue with the refill procedures outlined above. Check the condition of the radiator cap and its gasket, replacing the radiator cap as necessary.