Heater Box Rebuild

[StanG]

I'm rebuilding the heater box on 6S1534 and was hoping for some guidance/insights.

The box itself is in pretty good shape with just a couple of small cracks in it and a small piece missing where the heater hoses enter (Pic 3). It still has the FoMoCo stamping on it (pic 4). The interior foam has all but disintegrated and the internal metal boxing with the flap that sits adjacent to the heater core (Pic 2) has light surface rust and some minor pitting but is still fully functional. The plenum chamber is made of cardboard material but I think is beyond saving.
The demister tubes are a paper type material with cardboard where they attach to the top of the dashboard.  Interestingly they are square shaped (Pic 1) and not round like the reproduction parts I have seen online. They don't have any rips or tears and aside from being dusty seem ok. I'm fine to re-use them but am curious as to whether they are a genuine part or not.
I was wondering about the following:

1. How do I best go about cleaning the internal metal box & flap unit? Light sanding gets alot of the surface rust off but I cant get into the tiny areas around the flap rod.
2. What is the best way to repairs the minor cracks in the heater box itself?  (see pics 3 and 4)
3. How is the foam held in place?  Adhesive or double sided tape etc?
4. Has anyone seen these square type of demister hoses before - are they original ones or replacements, possibly done many years ago?  Does anyone have any pics of the real things so I can compare?

Appreciate any advice or insights

[corbins]

If I remember correctly... all the foam is self adhesive. Box repairs can be made with fiberglass from the inside, or you can try a 3M product called 8115..not designed for this but works well. Flapper will do well with a light bead blasting or just some good wire brushing. All Mustang vendors sell the kit to refurbish. Throw away the heater core and replace and double check or replace the blower motor... unless you want to do this all over again later .

[Greg]

1. How do I best go about cleaning the internal metal box & flap unit? Light sanding gets alot of the surface rust off but I cant get into the tiny areas around the flap rod.
    (There are a lot of products to clean with.  A scotch bright pad and WD 40 does wonders then use brake clean.)
2. What is the best way to repairs the minor cracks in the heater box itself?  (see pics 3 and 4)
    (Any fiber glass repair kit will fix this but prep is 100% key to success.  You must clean it and use 80 grit to sand around the area or you will have adhesion issues.)
3. How is the foam held in place?  Adhesive or double sided tape etc?
    (Adhesive, make sure you clean it all off really well, acetone works really well on this)
4. Has anyone seen these square type of demister hoses before - are they original ones or replacements, possibly done many years ago?  Does anyone have any pics of the real things so I can compare?
    (They look original but others will need to chime in as I'm not that familiar with all aftermarket products for this)

Appreciate any advice or insights
[/quote]

Enjoy the journey!

[Bob Gaines]

I'm rebuilding the heater box on 6S1534 and was hoping for some guidance/insights.

The box itself is in pretty good shape with just a couple of small cracks in it and a small piece missing where the heater hoses enter (Pic 3). It still has the FoMoCo stamping on it (pic 4). The interior foam has all but disintegrated and the internal metal boxing with the flap that sits adjacent to the heater core (Pic 2) has light surface rust and some minor pitting but is still fully functional. The plenum chamber is made of cardboard material but I think is beyond saving.
The demister tubes are a paper type material with cardboard where they attach to the top of the dashboard.  Interestingly they are square shaped (Pic 1) and not round like the reproduction parts I have seen online. They don't have any rips or tears and aside from being dusty seem ok. I'm fine to re-use them but am curious as to whether they are a genuine part or not.
I was wondering about the following:

1. How do I best go about cleaning the internal metal box & flap unit? Light sanding gets alot of the surface rust off but I cant get into the tiny areas around the flap rod.
2. What is the best way to repairs the minor cracks in the heater box itself?  (see pics 3 and 4)
3. How is the foam held in place?  Adhesive or double sided tape etc?
4. Has anyone seen these square type of demister hoses before - are they original ones or replacements, possibly done many years ago?  Does anyone have any pics of the real things so I can compare?

Appreciate any advice or insights

Your demister tubes are assemblyline correct for your 66.The square tube is not reproduced. The cardboard piece that fit the dash is easily damaged  so be careful .

[StanG]

Thanks for the detailed advice and tips. Greatly appreciated.
I'm one of the lucky ones to still be working in the current environment. I'll get into it on the weekend.
Cheers

[StanG]

Hi all,

Firstly - apologies for the lengthy post, but given the guidance and advice, I wanted to say thanks and share the results which I'm really happy with.  I also shared this on the Concours forum, so apologies for the double up, but I wanted to say thanks to everyone as the advice was invaluable to a person starting out like me.

It has taken me a few weekends but I finally got the heater box and demister tubes done.  I was able to clean the light rust with Citric Acid and steel wool (Doug on the concourse fourm was right - I was amazed), and used Evaporust for the ones that need a bit more effort like the heater fan basket. The parts came up really nice  - even the little balancing weights on the fan blades. I can clearly see "Torrington" and "408 Air Rotor" on the bottom.  I elected to coat them in a satin finish clear coat to prevent further rusting but keep the 'bare metal' look.  Thanks to the forum tips, I was able to reuse the original heater element including the plastic retainers and the original rubber gasket for the heater motor.  The small retainer clips on the motor shaft are still there and I'm just waiting on replacement wires from Virginia Classic Mustang to arrive to complete the motor itself as mine had been cut and rejoined.

The heater box itself came up a treat (pic 3).  I was able to fix the cracks.  It took a while, but I also rebuilt a part of the broken edging, including the inside edge 'trough' (pics 1 and 2) and the small indent where one of the retainer clips goes using Q-bond and a Dremel. Its expensive stuff, but I cannot fault the results.

I couldn't save the Plenum, however Phil Beresford supplied me with a replacement original, so all good there with just a Scotchguard treatment.

Bob Gaines was right about the demister tubes, they are VERY fragile!  The tubes themselves are in good condition.  There was a couple of pieces broken from the cardboard top, however when I (very tentatively - thanks Bob) removed them, the broken parts dropped out of the bottom of the tubes.  It appears they fell inside and sat there for who knows how long. I set about putting the cardboard jigsaw back together and the one missing piece was replaced after a '54 year old piece of cardboard' donation from my old (and un-salvageable) plenum which was a great color match.  I cut the plastic ends off a Scott Drake set to make a perfect template to ensure it all went back together correctly.  A clean up, light dusting with paint for cover (pic 4) and Scotchguard later and they came up pretty well.

For the demister tubes reinstall, I plan to use the Scott Drake plastic ends that I made for the templates and slide them over the tubes to provide support for the cardboard where it hangs from the dashboard - particularly where the retaining clips go in.  Essentially the plastic distributes the weight evenly and the original cardboard just rests on top of it with the retainers holding it all in place. You cannot see them and as nothing is stuck together, its easily removed in future. I figure it will reduce the strain on the flimsy cardboard - particularly around the retainer hole area - and hopefully help it last another 50 years.  I checked with the retainer clips and it all fits.

Now just need to keep an eye out for the postman so I can finish the motor wiring.

Cheers - and once again thank you for the invaluable guidance and advice.

Stan

[DennyD]

Beautiful work Stan, it looks amazing now.

[Shelby_r_b]

Looks fantastic, Stan! Well done, and thanks for the explanation.

[Bob Gaines]

Great job.Thanks for sharing. I am sure you have inspired others which is what we need.

[Greg]

Looks great!

[Grumpy]

#2378 is goin threw a restoration at
https://www.facebook.com/charleyhuttonscolorstudio

Search for 66 GT 350 convertible on his site. They did the heater /ac box over for the car. Looks good to me BUT I am not into it like others here. Maybe some info for ya or a good laugh