1989 RS Convertible, 700-R4, 305 TBI Replaced with a 383 Blueprint Engines Long Block.

So in removing that EGR Tube that runs to the exhaust, with engine in car, I accidently knocked a hole in the heater box, about 2" wide and maybe that high as well.

I removed the heater core, and while I'm thinking the repair would be easiest from the inside, since engine is in car, and I can see the hole from the inside; I can't get my ham hands in there to fix it with just the heater core removed.

I have not removed anything else under the dash yet, but what I needed to in order to remove the heater core.

I can't find any pictures or diagrams of what else I'd need to remove from the inside in order to make the repair from the inside and hopfully do nothing more then minor sanding & rattle can of repair from engine side as with engine in car anything else looks impossible.

So with that said, my questions are:
1. What else needs to be removed from inside to do this?
2. Has anybody done such a repair and what approach did you take and how'd it work out?
3. I'm thinking dyna glass, with matting, but I'm not sure the fiberglass will stick to whatever kind of plastic the heaterbox is made out of; is it ABS or?
4. What other options do I have for heater box repair or replacement with engine in car?

thanks in advance.

 

I have an idea. It's what I was going to do to try to fix mine when I removed my engine. There isn't much clearance to get to the rearmost exhaust bolt and I managed to put a hole in my box while trying to get that bolt out. I will be changing to the non-A/C box, so I don't need to actually do the repair anymore, but what I thought of was to make the hole round and just snap in a rubber or plastic plug.

 

The AC box, engine side, comes out with about 3 or 4 bolts or nuts across the top (larger ones... not the 7mm ones) from the engine side; and a similar number across the bottom, from the interior, under the edge of the carpet. THE WHOLE BOX. You can then take apart the 7mm screws to separate the 2 halves of the box, et voilà! you can work on it on the bench. Once you have it loose, you'll see it's a total piece o cake to patch that place. You'll also notice that it's all crumbled to dust all around that spot where it's close to the exh manifold. No need even to discharge the AC.

I'm betting what you'll find inside that box, besides the evap, will make you vomit.

Fiberglass is your friend. You can even paint it that baby-poop brown color if you want, so that it doesn't show an obvious repair.

 

Boat shops often do a good job at fiberglass repairs. I've been meaning to have my box reshaped to clear my engine. They quoted me less than $150 and your job is much more simple.

 

I've just been puttung this off forever, I just keep looking at it and it looks like i have to remove the receiver/dryer and discharge the a/c in doing so. Before I busted the lower heater box I paid over $1,600 bucks getting the a/c fixed by a place locally that works on older r12 systems; which they told me are colder and better systems then the new one's the EPA is trying to force us into; when I asked about updating to a modern compressor.

So anyway I really don't want to discharge the a/c, so I'm trying to figure out how to get that heater box out without removing the receiver/dryer, discharging the expensive r12. You seemed to infer no a/c discharge was needed but I guess I'm missing something. I don't see how you can remove the engine side heater box in one piece without unscrewing that receiver dryer going into the heater box first and losing all your r12.

It's unbelievable in 2022 they're no plug & play complete heater, a/c systems available yet from vintage air or anybody else as far as i can tell for third gens at the time of this post; i need to keep what i got for now.

Or stock replacement dashcenters, besides the no hole, one piece fiberglass ones for race cars.

Sure be glad when the aftermarket folks stop treating 3rd gens like the homely, unwanted, red headed step child.

 

Look across the top of the whole box, where it attaches to the firewall. Kinda behind that big fat wiring harness. You'll see about 4 (I think) bolts going through it. 10mm heads I think, but maybe larger, maybe 13mm. Then pull back the top of the pass side carpet; you'll see about 3 more like the others in there. Take em all out. The box will come off of the firewall. There might be one or 2 behind the blower motor, I don't think so but it's been like 30 years since I did it to mine so the details are a bit hazy.

Then once it's out in the open, you'll see that there's about 2 dozen 7mm screws holding the 2 halves of it together. Take those out, and the box splits, leaving the evap itself in place.

Too eeeeeezy.

 

i see the bolts to remove the box from the firewall but it looks like you'd need to take the top half off to clear the receiver dryer without having to unthread it and lose all the r12. does not look to be anyway to remove heater box in one piece without losing r12.

 

The accumulator comes out with the evap housing. One screw takes it loose. Might have to take another screw loose that holds the liquid line to the "frame" to allow it all to move around enough.

You DO NOT have to bust it open to get at the housing.

Just DO IT, you'll see.

 

I used fiberglass to re-do the lower part to remove the peak that is by that center screw. Its subtle, so you probably wont notice it, but it was done to clear the coil that usually contacts the cover. I had to cut a section out and bend the peaks to flatten it, then glass it. The top piece is just ABS, so i just took my heat gun to it.
Did this after the eng was installed, so you dont have to remove/disconnect the system. I did remove blower motor and the top cover. IIRC i think i took the dryer and whatever it is connected to out w/out uncoupling the system.

 

Sent you a pm concerning your Billet hinges, Ron

 

What did you use for your lines to the heater core? That looks good.

 

Those are DIY I made from various sections of aluminum tubing. Later I replaced the rubber hose with silicone pieces.

 

I don;t see a hole on the housing, so I don;t know where the hole is. how ibg it is.......... but why not just get a scrap piece of plastic or sheet metal, cut a square, and use some good RTV and shove it against the hole? Depending where the hole is, you could put a small screw to hold the piece in place... as long as it doesn;t go through the evap