85 heater core questions

[SpaceGoat]

How hard is it to get to the heater core? Anyone know of a good instructional website?

Thanks

 

[vetteboy86]

I have heard nightmare stories about it. I do recall reading a corvette fever article about that removal. You might want to search there site.

 

[Midnight 85]

I did the heater core in my 85 and it was a true pain, however it's better than paying someone to do it. Here goes:
Take the passenger seat out completely and lay a blanket over the track studs so they won't be jabbing you in the back, you're going to be there a while. Drain the cooling system and remove the heater hoses from the core at the firewall. You will need to drop the ecm down and out of your way, I didn't disconnect it, just laid it aside. There is a round bar brace coming from the side of the car up to the dash, this has to come out. I believe the bolts are either 13 or 15mm. The top one is a bear to get out, if you have the swivel sockets sold by Sears and a few others it will make life a lot easier. If not then it can be removed with an open end wrench and a prybar to use as a lever to move the wrench, you'll see what I mean when you get under there. Next you will see a vacuum line that is orange, move this out of your way. Then there is a threaded rod coming out of the heater box that is attached to your heater control cable, mark the cables position on the rod and remove it and get it out of your way. Next there are 7mm screws around the perimeter of the heater box, two of these you will need some type of mirror to see them. I used a small telescoping mirror and it worked just fine. Get all the screws out and you can take the box out now. At the top and bottom of the core there are two more 7mm screws holding it in, take these out and you're ready to remove the core from it's housing. Carefully remove it and now you're ready to do everything again,, in reverse. I worked on mine a few hours a day over a two day period, it's not hard, just aggravating at times. One tip I can give you is to get a good core, GM or NAPA would be my choice. I used a NAPA. Be careful putting the core back in it's easy to bend the lines. It should go straight back in but when you're laying on your back, looking up and working over your head things tend to get a little dis-oriented.
One last thing, when you are putting the box back on make sure you place the threaded rod back through it before you bolt it up. Please don't ask me how I know this. Good luck.

 

[SpaceGoat]

Everything seems so much easier on paper! Your post has helped me a lot though. Now I'm kindof stuck. Just started today, removed the seat, drained the coolant (what was left), started taking apart the dash. Thats where I'm stuck.. do you have to go the whole nine yards? What has to be removed from the interior to get to the core? Which hose is the heater hose? Where is the ECM and what does it look like? Do you happen to have any pictures?

Thanks for you help,
Mark

 

[Midnight 85]

Spacegoat, you have mail.

 

[Moonunit 451]

Spacegoat, you have mail.

Welome to Midnight! You have already done a great service to the members with your description of one of the most difficult DIY repairs on the early C4's. Thankfully I haven't had to do this yet myself.

I bet you're not a bigboy either, unlike myself :L

 

[Midnight 85]

Thanks for the kind words, glad I could help.

 

[Doug 87L98]

If you are not done yet, Corvette Fever October 05 has an article about changing a heater core.

One word "7mmswivelsocket" Not a universal joint and a 7mm socket
It will make your life so much easier!

 

[scorp508]

Fastguy did his '88 in next to no time at all just removing the hush panel and ECM. He couldn't understand why everyone says it is so hard. I have yet to do it myself, so I can't really comment on it.

 

[SpaceGoat]

Finally done. It was a major PIA at certain points! Overall wasn't too bad, still better than paying someone to do it. Thanks again midnight