Author Topic: Heater Box Rebuild  (Read 3139 times)

Offline StanG

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Heater Box Rebuild
« on: April 19, 2020, 04:41:38 AM »
I'm rebuilding the heater box on 6S1534 and was hoping for some guidance/insights.

The heater 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 4). It still has the FoMoCo stamping on it (pic 5). The interior foam has all but disintegrated and the internal metal boxing with the flap that sits adjacent to the heater core (Pics 2 and 3) 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 with very fine paper 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?  It has a fibrous looking finish, a bit like fiberglass, on it but not sure what it is made of. (see pics 4 and 5)
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.

Offline StanG

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Re: Heater Box Rebuild
« Reply #1 on: April 19, 2020, 04:43:11 AM »
Pic of the demister tube

Offline DougDyar

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Re: Heater Box Rebuild
« Reply #2 on: April 19, 2020, 10:31:53 AM »
To answer one of your questions, I'd suggest using citric acid to clean the metal box with the flapper doors.
Citric acid is a powder used in baking and cooking. I bought a 10lb bag on Amazon. Mix it with water. I mixed 5 parts hot water to one part acid by volume.
Soak anywhere from a couple of hours to overnight in a plastic Tupperware container or a plastic bucket. Try to use a container that's big enough to immerse the entire part.
Use some 0000 steel wool to help remove the corrosion and soak some more.
Rinse in water. Spray with WD40. You'll be amazed.
When you're done, dilute with more water and pour down the drain. It's not toxic once diluted.
Doug
« Last Edit: April 20, 2020, 09:58:20 AM by DougDyar »
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Offline CharlesTurner

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Re: Heater Box Rebuild
« Reply #3 on: April 19, 2020, 12:01:01 PM »
I've had nice results soaking in evaporust. 

There are some prior discussions on the forum regarding restoring the boxes.
Charles Turner - MCA/SAAC Judge
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Offline Bob Gaines

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Re: Heater Box Rebuild
« Reply #4 on: April 19, 2020, 02:01:47 PM »
I'm rebuilding the heater box on 6S1534 and was hoping for some guidance/insights.

The heater 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 4). It still has the FoMoCo stamping on it (pic 5). The interior foam has all but disintegrated and the internal metal boxing with the flap that sits adjacent to the heater core (Pics 2 and 3) 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 with very fine paper 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?  It has a fibrous looking finish, a bit like fiberglass, on it but not sure what it is made of. (see pics 4 and 5)
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.
The square demister tubes are correct for your 66. They are not reproduced . The cardboard piece on the dash side is very fragile and consequently seldom intact after removal. Be careful.
Bob Gaines,Shelby enthusiast, Shelby collector , Shelby concours judge SAAC,MCA,Mid America Shelby

Offline J_Speegle

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Re: Heater Box Rebuild
« Reply #5 on: April 19, 2020, 04:32:46 PM »
An example from an original car to illustrate the original shape of the defroster hose

Jeff Speegle

Anything worth doing is worth doing concours ;)

Offline StanG

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Re: Heater Box Rebuild
« Reply #6 on: April 20, 2020, 11:13:19 AM »
Thank you all. Really appreciate the responses.

I'm stoked that the tubes are original.  They look like they are in good shape but I'll take the advice and be cautious with them. It's ashame that I don't think I'll be able to save the plenum chamber.  Is there a clamp of some sort that holds them onto the plenum? The pic looks like they just sit on them.

I"ll give your suggestions for the heater box clean a try. Fingers crossed.

Thanks again!

Offline CharlesTurner

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Re: Heater Box Rebuild
« Reply #7 on: April 20, 2020, 01:42:03 PM »
No clamps on the defroster hoses.  There's a ridge on the top edge of the heater plenum that holds the hoses on.
Charles Turner - MCA/SAAC Judge
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Offline jwc66k

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Re: Heater Box Rebuild
« Reply #8 on: April 20, 2020, 02:55:14 PM »
No clamps on the defroster hoses. 
The upper end is stapled to the duct outlet.
When you get the duct outlets and plenum "cleaned", spray them with Scotch Guard. It's a moisture repellent, will be absorbed into the fiber material and will not be seen.
Jim
I promise to be politically correct in all my posts to keep the BBBB from vociferating.

Offline StanG

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Re: Heater Box Rebuild
« Reply #9 on: April 22, 2020, 10:35:09 AM »
Thanks.  I thought the lamps may have gone missing. Give the plenum is not in great shape the fit was very loose.

Great tip on the scotch guard - will definitely do that one. The cardboard ends are very dried out but hanging in there at thispoint.

Cheers

Offline StanG

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Re: Heater Box Rebuild
« Reply #10 on: June 21, 2020, 05:44:37 AM »
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.

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 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 (pic 5) 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.  I was able to fix the cracks (pics 1 and 2).  It took a while, but I also rebuilt a part of the broken edging, including the inside edge 'trough' (pics 3 and 4) 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 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 (pics 7 and 8 ), 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 (pic 9) 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 (pic 9 top hose).  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 10) 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

Offline Bob Gaines

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Re: Heater Box Rebuild
« Reply #11 on: June 21, 2020, 11:14:56 AM »
Great job!!!
Bob Gaines,Shelby enthusiast, Shelby collector , Shelby concours judge SAAC,MCA,Mid America Shelby

Offline J_Speegle

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Re: Heater Box Rebuild
« Reply #12 on: June 21, 2020, 03:57:16 PM »
Nice job - Thanks for sharing. Helps others realize what they can do themselves and provides that motivation
Jeff Speegle

Anything worth doing is worth doing concours ;)