2000 GT Heater Core

Recently developed a problem with my heater. Whenever it is really cold out (which just started happening) the windshield and all of the windows will fog up really bad. I turn on the defroster and it barely does a thing. My coolant looks brown...my guess for this is good old "dex-plug", whoever had it before me combined green coolant and dexcool which do not mix very happily. So, commonly I know this clogs your heater core and just leaves a mess resulting in it needing to be replaced and your system flushed. So, my question is, how do I do it?

I have done alot of DIY and I understand it is a very frustrating and time consuming job, but for a poor college kid, I am willing being home for winter break.

If anyone has pictures associated with what I need to remove to get to it or general directions, I need to know how to drain the system, remove the core, and replace it with a new one. A parts list wouldn't hurt either... I already know I will need the core and some coolant, just don't know how much coolant or if I need replacement gaskets also.


Thanks! (I have a feeling my good mood will change tomorrow when I start to get into this job):confused:

Just to clarify have you flushed the cooling system yet? How about forward or back flushing just the heater core in addition to the rest of the cooling system since you appear to have sludge? Try this first before replacing the heater core.

If you need a flushing procedure we have it posted in old threads. Let us know if you need it.

Yeah that would be great if you guys could provide a link to that! I tried looking for it myself and can't seem to find it, I just need the directions to flush the entire system so that I can get that brown crap out of there.

Thanks in advance!:evillol:

This is a general cooling system flushing procedure that many of us have used. Recommended to use the Prestone brand flushing kit or similar.


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

Top Heater Hose = return
Bottom Heater Hose = pressure

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 (Caution: 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 5/150 antifreeze/distilled water (or buy premixed 50/50).
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.

Okay sounds pretty easy, just two more questions. I bought the T for the hose and just wanted to know how I was supposed to connect it to it considering the threads on the connector are male and the connector on the end of my hose is male as well....
Also, once I install the T into the line, do I just leave it in after the procedure or do I need to remove it?

Did you get the Prestone Kit or just piecemeal parts?

You can leave the tee in as long as the tee has the cap and the fitting is properly clamped down to the hoses.

I just got the piece separate, I didn't buy the whole kit. As for connecting the hose do I just need to makeshift something or is there an easier way?

Without seeing the fittings you have I really can't tell what you are getting at. But it is simple. You cut the respective heater hose in a good spot and add the tee connector which is typically around 5/8" for heater hose.

The pic below shows how the special tee with cap from a Prestone brand kit was spliced into one of the heater hoses. It was left in place and has been there for over two years so it will come in handy for future flushes.

http://i5.photobucket.com/albums/y186/lizzywiz/DSC05224.jpg

Took it all apart and had a little bit of a conclusion. The inside of the entire system has brown flakes allllll over in it. I could literally take a scoop of brown gunk out of the area where the radiator cap is at. So here is my conclusion, tell me if I am thinking correctly here.

The entire system needs to be flushed professionally.

All of the hoses need to be replaced.

+ the heater core will need to be replaced before it explodes in my passenger floorboard.

I filled it back up with 50/50 from prestone and set it outside...think that it will probably go in the shop after the holidays here when I have a little more money.

What do you guys think, any insight here would help...

:uhoh::uhoh::uhoh::uhoh::uhoh::uhoh::uhoh::uhoh::u hoh::uhoh::uhoh::uhoh::uhoh::uhoh::uhoh:

Does anyone have a diagram of where the heater core is located in a 2000 grand prix GT 3.8? I know its on the passenger side after I remove the dash, but want to know exactly what I am getting myself into before I begin.