Heater Hoses

I am about to change the antifreeze in my 98GP using the Prestone flush kit and am unsure which is the return heater hose. Is it the top or bottom hose which goes from the engine into the car body?

The top hose at the firewall going to the heater core is the return line back to the tensioner assembly.

Thanks Mr. Naylor.

You're welcome.

If you need any further assistance let us know. Did you reference the flush procedure we have at any of our old threads? Also, make sure the water from the city supply is not turned up too high since pressure can average at least 50 psi.

Thanks again. I looked at the procedure for flushing the rad but I am a bit scared about the procedure for flushing the water from the engine block after the rad is clean. Am I to assume that starting the engine with the rad plug and the Tee open will safely remove the water from the block?

Are you referring to step 5? I've had no issues doing this way and I recall other members used the procedure. Otherwise, you will have to find and undo the engine block drains to drain the water out which is a PITA. The biggest problem with not getting as much water out of the system as you can will be getting the right premix of water and coolant for proper boil over or freeze protection.


Install the flush T from the Prestone Flush Kit in the heater return line hose per the instructions on the label.

1. With engine cool, remove radiator cap and drain the radiator.
a. Turn drain plug (lower left engine-side of radiator) counter clockwise about 1/8 of a turn (may require a little force if it's not been opened in awhile--be careful because it's plastic). Use the end of a 1/4" drive handle. Plug will extend slightly as it loosens. Be sure to have a container in-place to collect the antifreeze.
2. Let all the antifreeze drain into a container.
3. Remove, drain and clean the antifreeze overflow bottle. Reinstall bottle.
4. Hook up a garden hose to the flush T and turn water on (not too high or you can damage seals/gaskets with the pressure). When water starts to run from the drain plug, start the engine and turn the heater on (make sure you leave the water running during this process).
5. When water runs clear (about 5 - 10 minutes), turn off car, then turn off water, and remove hose from T and cap it. Let remaining water run from drain plug. (Note: Not all of water will be drained out of system mainly the engine block. What I do is hook up a drain hose to the T connector, start engine and let the water pump push water out of the system. As soon as you see no water coming out turn engine off, remove drain hose and cap off T connector).
6. Close radiator drain plug and fill radiator with a 50-50 mix of extended life antifreeze/distilled water (or buy premixed).
7. Start vehicle and bring to operating temperature to make sure thermostat opens. Add additional mixture as necessary until full.
8. Reinstall radiator cap.
9. Release any trapped air in cooling system by turning the plug on the top of the thermostat housing (be careful not to burn yourself). When only coolant (no air) flows from the plug, close it. You may have to repeat this several times to get all of the trapped air. Raising the front end of the car where the radiator is higher than the engine helps bleeding.
10. Add additional coolant as necessary. Also, fill overflow bottle to recommended level. Be careful not to open radiator cap if hot. You may have to do this several times.
11. Check for leaks.
12. Properly dispose of old antifreeze.

I am referring to step 5. Can I assume that you mean to hook a short piece of hose to the T connector so that the water remaining will run off away from the engine compartment? If so, then I will give it a try.

I am referring to step 5. Can I assume that you mean to hook a short piece of hose to the T connector so that the water remaining will run off away from the engine compartment?

Thats correct. Unless you can think of a better way.