Heater core replacement
Thread Starter
Joined: Dec 2001
Posts: 4,909
Likes: 3
From: Cleveland, OH
Heater core replacement Thought I would write up what it took to do it. Sorry, no pics.
Start by draining the radiator.
Locate 2 heater hoses that go into the passenger compartment.
Remove clips. MUCH easier said than done; this took the longest. Recommend you remove the passenger side coil packs so you can get at it.
Once off, remove 7mm bolt between the 2 pipes. Tight fit again, may have to lay across engine to see.
You're now ready to go inside the passenger compartment.
First remove the cover under the glove box. 2 plastic clips and a metal clip at the bottom. I used a screwdriver for all 3.
Now remove the glovebox. 3 7mm bolts hold it in.
Now remove the cover to the heater core. 2 7/32 bolts hold it in.
Now remove the clip holding the heater core in, 1 7/32 bolt.
Carefully slide the old heater core out.
Lay it on a workbench with the new one next to it in the same orientation.
There is a rubber gasket and connecting metal piece between the 2 pipes you removed the hoses from in the beginning. Remove and install onto the new one in the same exact location.
Reverse the process for reinstall. Remember to burp the system when refilling with coolant. Turn the heat on. Disregard the nasty smell, it's the new heater core 'burning' in. It did go away after a while.
What prompted this was I was on the dyno 2 days ago and noticed smoke coming out of the center vent, and it smelled like coolant in the car. In addition, several days last week my window was fogging up along the bottom. WITHOUT the heat on, same with the dyno. Didn't get the infamous wet carpet but figured it wasn't far away. Did a pressure check, all is well but my cap was toast too, so replaced that.
Core - $80 at Autozone, cap $6.00, fluids $22.00.
Total time till I started putting coolant in - 2.5 hours. Not terrible considering it was just 'let's see what bolts to undo to get this done'.
Start by draining the radiator.
Locate 2 heater hoses that go into the passenger compartment.
Remove clips. MUCH easier said than done; this took the longest. Recommend you remove the passenger side coil packs so you can get at it.
Once off, remove 7mm bolt between the 2 pipes. Tight fit again, may have to lay across engine to see.
You're now ready to go inside the passenger compartment.
First remove the cover under the glove box. 2 plastic clips and a metal clip at the bottom. I used a screwdriver for all 3.
Now remove the glovebox. 3 7mm bolts hold it in.
Now remove the cover to the heater core. 2 7/32 bolts hold it in.
Now remove the clip holding the heater core in, 1 7/32 bolt.
Carefully slide the old heater core out.
Lay it on a workbench with the new one next to it in the same orientation.
There is a rubber gasket and connecting metal piece between the 2 pipes you removed the hoses from in the beginning. Remove and install onto the new one in the same exact location.
Reverse the process for reinstall. Remember to burp the system when refilling with coolant. Turn the heat on. Disregard the nasty smell, it's the new heater core 'burning' in. It did go away after a while.
What prompted this was I was on the dyno 2 days ago and noticed smoke coming out of the center vent, and it smelled like coolant in the car. In addition, several days last week my window was fogging up along the bottom. WITHOUT the heat on, same with the dyno. Didn't get the infamous wet carpet but figured it wasn't far away. Did a pressure check, all is well but my cap was toast too, so replaced that.
Core - $80 at Autozone, cap $6.00, fluids $22.00.
Total time till I started putting coolant in - 2.5 hours. Not terrible considering it was just 'let's see what bolts to undo to get this done'.
i love how easy it is to change out on an f-body compared to other cars.... i did one on a 95 5.0 rustang and it sucked buckets of ***..... i had to remove the entire dash... steering column everything... and doing it by yourself is no fun since the entire dash weights so much.... that is just another reason why camaros are better then mustangs
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TECH Enthusiast
Joined: Nov 2001
Posts: 688
Likes: 2
From: Derby, KS
I changed mine today just because I can't afford to have it crap out on me. The old one looked very nice, at least on the outside. It was 9 years old and had 91,200 miles on it. Thanks Viper for posting the run down of how to do it, it was very helpful. Couple of things I'd like to add:
1) On my '98 the bolt between the pipes was a 6mm not a 7.
2) The OEM unit I took out (available for $105 from GM Parts Direct) was all aluminum, the one I got from Autozone ($65) was copper. Aluminum ones last about twice as long as copper ones, although the Autozone one carries their limited lifetime warranty. I had some fitment issues with the AZ unit, not huge ones but still something to consider. It would not accept the retaining clip on the inside because it did not have the side bar that the OEM unit does, I bent the clip around in the vise and made it work. The pipes were at a slightly different angle and had to be massaged when installing the retaining clip. If I had it to do over, I'd have spent the extra $40 on the OEM unit.
3) The "heater core cover" on the inside of the car, is a big plastic piece with a round bulge in it. From the outside it looks like that is where the blower motor is but no, that's where the heater core is. It was not immediately apparent to me which hunk of plastic I needed to remove, so I hope that description helps somebody else.
4) Those OEM spring type hose clamps are a bear to get off (because you are working so far under the cowl) and not much easier to get on, I would take the opportunity to toss them in favor of standard worm type clamps, as I did. There's a tool that makes removal of those spring clamps much easier, I had one, but it had a 45 degree offset, a straight one would have worked a lot better.
1) On my '98 the bolt between the pipes was a 6mm not a 7.
2) The OEM unit I took out (available for $105 from GM Parts Direct) was all aluminum, the one I got from Autozone ($65) was copper. Aluminum ones last about twice as long as copper ones, although the Autozone one carries their limited lifetime warranty. I had some fitment issues with the AZ unit, not huge ones but still something to consider. It would not accept the retaining clip on the inside because it did not have the side bar that the OEM unit does, I bent the clip around in the vise and made it work. The pipes were at a slightly different angle and had to be massaged when installing the retaining clip. If I had it to do over, I'd have spent the extra $40 on the OEM unit.
3) The "heater core cover" on the inside of the car, is a big plastic piece with a round bulge in it. From the outside it looks like that is where the blower motor is but no, that's where the heater core is. It was not immediately apparent to me which hunk of plastic I needed to remove, so I hope that description helps somebody else.
4) Those OEM spring type hose clamps are a bear to get off (because you are working so far under the cowl) and not much easier to get on, I would take the opportunity to toss them in favor of standard worm type clamps, as I did. There's a tool that makes removal of those spring clamps much easier, I had one, but it had a 45 degree offset, a straight one would have worked a lot better.
Last edited by Dave Carney; Nov 24, 2006 at 05:28 PM.
12 Second Club
iTrader: (4)
Joined: Dec 2007
Posts: 1,712
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From: Between Bowling Green/Owensboro
I have 156k miles.. was crusing and my windshild starting fogging last night..started to smell coolant.. this write up is very handy. Ill be getting the autozone unit as well.
Thanks guys.. thought I would bring this up from the dead
Thanks guys.. thought I would bring this up from the dead
My windshield isn't fogging up but I replaced my opti and did a radiator flush and a week later no heat, checked all my fluids and everything is good, and bleed the air out. So I guess I will take out the heater core and try to see if any sludge will come out. If so I guess I will buy a new one, but if it's clean then I dunno what else it could be. I don't think a Granatelli cold air tuned maf would cause any problems with my heat right? That's the only other thing that has been changed on my car since the heat stopped. But thanks for the write up, I'm sure it's easier wrote then done but if it was to easy it wouldn't be any fun! 
Does anyone have a picture of this? I forgot to cut a passageway for the blower when I did my AC block off plate. Was just curious if I could get in there and make a hole without having to pull the front plate off since the engine is in the car.
