[Steve Barcak]

My core is leaking ( I know- NO ONE wishes they were me).

Am curious who has made this repair?

Does the dash pad have to come out? or can you get the heater box out with the dash in place to swap the heater core? It seems you cannot.
Then, there is the suitcase-

Have already pulled the console, passenger seat, r fender well.
Have suitcase somewhat loose, etc It does not appear I can remove it without pulling the fender too. ugh

I've replaced heater cores in several GTOs and Catalinas and this Firebird seems 10 times as difficult so, am learning to hate the car because of it.

Hoping I do not have to pull the dash assy but, it appears I do.

Anyone done this have any tips? thanks

[nUcLeArEnVoY]

You don't have to pull the entire dash, no. You do need to get the glove box out, and the more ducting you remove, the easier it is to pull it out and stuff it back in. It helps to remove the passenger side vertical dash vent (not the chrome ball chiller one), and that duct is challenging to reinstall because one of the screws is very difficult to get to with the dash still in place. Re-installing it is significantly harder than pulling it out, since the clearance is minimal thanks to the heater core outlet tube, and obviously you're going to want to be careful with the new one since the joint mating the tube to the matrix is very fragile.

And while it's not mandatory, it makes the job a lot easier if you pull the fender well, which is also challenging to reinstall since it's sheet metal rather than plastic like modern cars. While it's out, you may as well replace the blower motor if you haven't already.

Finally, to help prevent this issue in the future and extend the life of your new core, either replace the heater hose fitting in the passenger cylinder head if it's a Pontiac engine, or maybe place an in-line piece of bar stock with a 1/4" restriction in the inlet hose and clamp it down with worm gear clamps so it doesn't move. The fitting in the cylinder head has a similarly restricted rubber insert in it that usually disintegrates over 40+ years, as was the case with mine. The reason the factory did this restriction was to prevent water hammer damage to the heater core during sudden acceleration that causes a sudden surge in pump pressure. Over time, this stresses the heater core and can lead to early failure.

[Steve Barcak]

I'll disagree about pulling the dash with optioned with a/c. I do not see how one can get the heater box out around that passenger duct. Trying to r and r that passenger duct while the dash is in the car would be a night mare IMO.
I ended up unbolting the dash in its entirety but, lifted and slid out the passenger side leaving the driver side in place. I used 2 1" ratchet straps to suspend the dash. This was a bit easier ( if the word 'easy' could be used) with the r t top removed and attached the strap hook to an attachment on my ceiling in my shop. with the strip holding up the dash, I was able to slide out the heater box and replace the core.
I ended up using a used core! some may think that is nuts but, I have been collecting Pontiacs over 45 years now and have many Firebird/TA parts cars for over 30 years. Heater cores do not age when dry and not in use. I pulled a clean one our of a 79 TA and used it.
On the heater nipple on the right head. A few years back, I replaced the original straight one with a 90 degree version used on the 265/301.
So, after this was done and the dash almost removed, I decided to dig deeper in the project and pulled the dash out.
some years ago, I had a dash restored for the car and had no intention to install it until I painted the car but, decided to install the new dash since I was this far.
With all my decades of working on GTOs and Catalinas, this is really the first Firebird that I have serviced. Have parted birds for decades but, this is the first one am restoring.
I can say, everything on the Firebird is more difficult to service over a GTO or Catalina. So, I am trying to keep liking the car though I would much rather work on one of my other Pontiacs.
Will be glad when it is over. Having a heater is a good thing. We got more snow the last few days here in eastern Az.

[65madgoat]

I somehow did it with metal dash etc not touched or removed but everything else under there ducting wise and glovebox had to come out and even then a total b*tch to put together. Fender was off too. Pain in the butt alright.

Never doing one again.

[Warren Seale]

I did mine about 40 years ago. It leaked because of a crack in one of the inlet/outlet pipes. When the car was built, the assembler had the pipe up against the edge of the firewall. The vibration over the years caused the pipe to crack. Be sure to center those pipes in the firewall holes.

I had to remove the inner fender, the glove box, and the passenger side ductwork to gain access to the heater core. You will need to get some new weatherstrip foam from the hardware store. This stuff disintegrates over time.

[jpg69bird]

I did mine last summer and did not pull the dash out. Removed everything else under the dash, but the dash stayed on.

Though, I did scratch the passenger kick panel. That was more from frustration and carelessness at the end of the day.

My issue was removing the fender well. The nuts holding the screws that attach it to the fender had spun. I had to take off the well and the fender as one piece.

[Steve Barcak]

this has turned into quite a job. ended up changing the dash out to a restored one I had tucked away for it. about half of the stuff on the dash now does not work- no blower motor, some of the dash lights, no turn signal indicators, volt/gas gauge change when you turn the lights on, etc.
So, will reluctantly pull this new dash out. hate to do that but, too much is wrong. So, while it is out, want to make more improvements including a new aftermarket type 2 way front speaker and some other things. do not really want to be doing this but, has to get done. yuck

[nUcLeArEnVoY]

Originally Posted by Steve Barcak

this has turned into quite a job. ended up changing the dash out to a restored one I had tucked away for it. about half of the stuff on the dash now does not work- no blower motor, some of the dash lights, no turn signal indicators, volt/gas gauge change when you turn the lights on, etc.
So, will reluctantly pull this new dash out. hate to do that but, too much is wrong. So, while it is out, want to make more improvements including a new aftermarket type 2 way front speaker and some other things. do not really want to be doing this but, has to get done. yuck

Project creep never fails, haha.

[burd]

This is exactly why I just looped mine, it’ll never be the same, and you don’t need all that heat in the dash in the summer with the ac on.

[Skip Fix]

My 78 blew the original core-maybe because the E heads were not restricted like the factory nipple. i just looped it!