Toyota Pick-ups/Land Cruiser/4Runner 1970-1988

Cooling System



When additional coolant is required to maintain the proper level, always add a 50/50 mixture of ethylene glycol antifreeze/coolant and water.


If coolant is visible above the 3 / 4 in. of the bottom of the filler neck. On later models, the cooling system has, as one of its components, an expansion tank.

Dealing with the cooling system can be a tricky matter unless the proper precautions are observed. It is best to check the coolant level in the radiator when the engine is cold. This is done by removing the radiator cap and seeing that the coolant is within Low or Min mark on the tank, the level is satisfactory. Always be certain that the filler caps on both the radiator and the reservoir are tightly closed.

In the event that the coolant level must be checked when the engine is warm or on engines without the expansion tank, place a thick rag over the radiator cap and slowly turn the cap counterclockwise until it reaches the first detent. Allow all the hot steam to escape. This will allow the pressure in the system to drop gradually, preventing an explosion of hot coolant. When the hissing noise stops, remove the cap the rest of the way.

It's a good idea to check the coolant every time that you stop for fuel. If the coolant level is low, add equal amount of ethylene glycol based antifreeze and clean water. On models without an expansion tank, add coolant through the radiator filler neck. Fill the expansion tank to the Full level on trucks with that system.

Never add cold coolant to a hot engine unless the engine is running, to avoid cracking the engine block.

Avoid using water that is known to have a high alkaline content or is very hard, except in emergency situations. Drain and flush the cooling system as soon as possible after using such water.

The radiator hoses and clamps and the radiator cap should be checked at the same time as the coolant level. Hoses which are brittle, cracked, or swollen should be replaced. Clamps should be checked for tightness (screwdriver tight only! Do not allow the clamp to cut into the hose or crush the fitting). The radiator cap gasket should be checked for any obvious tears, cracks or swelling, or any signs of incorrect seating in the radiator neck.


See Figures 1, 2, 3, 4 and 5

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.

Completely draining and refilling the cooling system every two years at least will remove accumulated rust, scale and other deposits.

Use a good quality antifreeze with water pump lubricants, rust inhibitors and other corrosion inhibitors along with acid neutralizers. Use a permanent type coolant that meets specification ESE-M97B44A or the equivalent.

  1. Drain the existing antifreeze and coolant. Open the radiator and engine drain petcocks (models equipped), or disconnect the bottom radiator hose, at the radiator outlet. Set the heater temperature controls to the full HOT position.

Before opening the radiator petcock, spray it with some penetrating lubricant.

  1. Close the petcock or reconnect the lower hose and fill the system with water.
  3. Add a can of quality radiator flush. Be sure the flush is safe to use in engines having aluminum components.
  5. Idle the engine until the upper radiator hose gets hot.
  7. Drain the system again.

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Fig. Fig. 1: Coolant drain plug locations-4 cylinder engines

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Fig. Fig. 2: Assorted coolant drain plug locations

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Fig. Fig. 3: Removing the radiator cap---only when the engine is COLD

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Fig. Fig. 4: Refill the cooling system

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Fig. Fig. 5: Windshield washer fluid bottle---do not mistake it for the coolant recovery bottle

  1. Repeat this process until the drained water is clear and free of scale.
  3. Close all petcocks and connect all the hoses.
  5. If equipped with a coolant recovery system, flush the reservoir with water and leave empty.
  7. Determine the capacity of your cooling system (see Capacities specifications). Add a 50/50 mix of quality antifreeze (ethylene glycol) and water to provide the desired protection.


Most permanent antifreeze/coolant have a colored dye added which makes the solution an excellent leak detector. When servicing the cooling system, check for leakage at:

All hoses and hose connections.
Radiator seams, radiator core, and radiator draincock.
All engine block and cylinder head freeze (core) plugs, and drain plugs.
Edges of all cooling system gaskets (head gaskets, thermostat gasket).
Transmission fluid cooler.
Heating system components, water pump.
Check the engine oil dipstick for signs of coolant in the engine oil.
Check the coolant in the radiator for signs of oil in the coolant.

Investigate and correct any indication of coolant leakage.

Check the Radiator Cap

See Figure 6

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Fig. Fig. 6: Check the radiator cap seal and gasket condition

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 and the engine will overheat.

A worn cap should be replaced with a new one.

Clean Radiator of Debris

Periodically clean any debris such as 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.


See Figure 7

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Fig. Fig. 7: Check coolant protection using hydrometer

A 50/50 mix of coolant concentrate and water will usually provide protection to -35°F (-37°C). Freeze protection may be checked by using a cooling system hydrometer. Inexpensive hydrometers (floating ball types) may be obtained from a local department store (automotive section) or an auto supply store. Follow the directions packaged with the coolant hydrometer when checking protection.