If your Trooper has a lot of miles on it, it is a good idea to change the radiator coolant. Check your owner's manual, but many manufacturers recommend changing the coolant every 30,000 miles. When you change your coolant, it is also a good time to check the condition of the radiator itself and your hoses.
Caution: coolant/anti-freeze is a poisonous substance. Do not allow this liquid to come in contact with your skin, mouth, eyes or any other body opening. Follow medical procedures on container if this should occur. Take any used anti-freeze/coolant to a regulated disposal site.
Note: These are general instructions. Consult an Isuzu Trooper repair manual for specific procedures.
The temperature of your Trooper should be cold; in other words, allow your engine to cool overnight or for several hours before beginning this procedure. With the parking brake applied and the ignition in the "off" position, grab a container that is large enough to catch approximately two gallons of liquid. You can either disconnect the lower radiator hose or open the cooling system access port. Permit the coolant to flow out of the system into your container. While the fluid is draining, check the condition of the heater and radiator hoses. Examine all hoses to see if any are soft, cracked, or punctured. If you find any of these conditions, replace the hose(s).
After replacement, check the hose connections to make sure they are tight. Check the front of your radiator to make sure that no dirt, debris, or leaves are blocking the front of the unit. Remove any that you find with a rag or soft vinyl bush. Also check the radiator for corrosion and/or rust. Rust or corrosion will interfere with the radiator's ability to cool your engine. If the radiator is damaged in this way, take it into a radiator repair shop to have it repaired or recored.
After the coolant has drained, move the heater control to the full "on" position. Remove the radiator reservoir cap. Fill the system with water. With the reservoir cap still off, start the engine and rev it a few times. Run the motor until the thermostat opens. (You can determine this by monitoring the radiator hoses. When they begin to feel warm, the thermostat has opened.)
Allow the motor to cool completely and drain out the water. If the water is not clear, repeat the previous procedure until the water is clear and free of contaminants.
Once the water is clear, follow the procedure above and fill the system with a 50/50 mixture of anti-freeze and water. Squeeze the upper radiator hose a few times to remove any air from the system. With the engine still running, turn on the heater blower motor and turn up the heater to maximum. If you feel warm air, it indicates you have purged all of the air out of your cooling system.
Add more of the coolant/water mixture until you have reached the "hot" level on the reservoir.
Now your Trooper coolant is ready to do the job it designed to do - to keep your engine at the proper operating temperature.
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