I'm not getting the air I should and I know there is a mouse nest or two up in there. Just wondering how to get in there on my '66 f85.

 

The fasteners for the heater box are on the engine side of the firewall, right side. The box comes out from under the passenger side dash inside the car. The far right stud fastener is a bear to get to and you may need to pop the right inner fender well out to gain access.

 

Thanks!!

 

pretty much can confirm on removing the pass inner fender. done it a few times on 66-67 cars. good luck.

 

You have 5 nuts to remove under the hood. I do not remove the inner fender, removing the inner fender is a very hard job, the inner fender is metal, it does not flex, it will not come out without taking some of the fender bolts out such as the bottom of the cowl and probably more. The inner fender lays on top of the core support where it attaches with 4 bolts and would need to be scooted back a few inches to get it off there, there is no place to scoot it. The fender and inner fender are meant to be installed and removed as a unit, bolted together. The inner fender fits into a lip inside the fender/wheel well, the fender is bent to form a groove for the inner fender and there is no room to get the inner fender out of the groove. You can get the nuts off the heater box, I am sure. A word of caution, after the 5 nuts are removed, if the inner box still seems to be "bolted" into place, check for additional nuts on the studs, between the outer box and the firewall. I have seen it more than once. I assume some line worker put them there to hold the inner box in place so the outer could be set on the studs. You need to remove the cables inside (try not to break the little "push" keepers that hold the cable on, they are an odd size, 5/32, and you will not find them at your local auto parts stores). and the wiring inside and the hoses outside. You will need to re-seal the outer box to the firewall when you re-assemble. Get a heater seal kit to you can replace the seals on the diverter doors, this will assure you do not get heat in the summer when you don't want heat.
I attached a link to auctions showing the heater box so you can clearly see where the 5 nuts are located, and the seal kit (Chevelle are the same as f85).
http://www.ebay.com/itm/64-72-GM-A-B...3c7510&vxp=mtr


http://www.ebay.com/itm/1964-65-66-6...7b1be9&vxp=mtr


Good luck,

 

I didn't remove my fender well to get to the far right nut. However I also found reinstalling the nut back on the stud is impossible, so I left it off. I just popped the box out, did not remove anything else. Replaced heater core and put it all back together. My new heater core had the bent tube which required an extra set of hands to get it back through the firewall and lined back up. Other than that it was a piece of cake.

 

Guys:
I have changed mine a couple times over the years, it depends on which side the nest is on, I was able to change my core from under the dash by removing the box that holds the cables and such, mine did not have A/C, that may be the difference. Otherwise pull it in the shop and figure on a day to do the job or find a GOOD shop and let them do it.
Thanks, Ron

 

That won't work on a 66. The inside box has studs that protrude thru the firewall with nuts on the engine side. The inside box does not have any access point for the core. IMO, you need to remove the fender to do the job right and reinstall ALL of the fasteners. Removing that side is pretty easy compared to the Drivers side. Re-installing the hood is the challenge, but made easier if you mark the existing location VERY WELL, and keep track of the fender shims placement. While you're at it - you may as well........... LOL, Just kidding!!

 

Man it's sad we can't access Wild About Cars free anymore.
I took a picture about what the shop manual says on the 66 Cutlass/f85.
Drill a 3/4" hole to access the difficult nut then use a "plug" with sealer to cover it. They even marked the spot to drill with a dimple!


Eric, I had to look, my outboard nut is missing also, on the car that is. Both my personal ones are A-OK.

 

I bet most are missing, the funny part was on mine I had the nose completely off the car not too long before the heater core started leaking. And on a personal note me too.

 

MAY I SAY BOYS its a cramp in the ***** type of job. wish i lived in a hot state where it would never need to be fixed, lol

 

Me too w45, it's in the 20's here today.

 

Having the seats recovered and new carpet installed so now is a good of time as any to clean out the duct work. I'm glad I have an ace helper, my son.