So I removed the under-dash heater box to replace my heater core.

When taking the heater box apart, I noticed that there was some kind of old gasket that looks like it was sealing (that's an over-exaggeration) the box together.

When putting it back in place, is there a new kind of gasket or material that people use to seal the box back up before putting on the spring clips around the edges?

DMT - Detroit Muscle Technologies - has heater box rebuild kits for both AC and non-AC boxes.

sent from my iPhone

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65 Dart station wagon slant 6 - now under construction
47 Dodge Custom 4 Door sedan
87 D100 Short Bed slant 6

Retired USAF 1966-1986
Retired US Postal Service 2004-2014

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1964 Dart GT

If you're not worried about restoration correct materials, I'd hit the local Home Depot, and check out what's available in weatherstripping. Seems to me some of that 1/4" thick x 1/2" wide foam tape would do what you needed.
But I'm a tightwad.

Roger

+1.

Home Depot sells generic weatherstripping in various widths and thicknesses b the roll. Several years ago I resealed the entire HVAC system in my bother's 83 Dodge van. Granted, it is a base model with a heater only and not even any dash vents, but I was able to replace every singe gasket in the fresh air and heat system for under $30 of materials purchased at my local Home Depot. I resealed the vent doors, the heater core, the air diverter, the heater box to firewall junction, everything. The van got quieter and the heat and fresh air got colder. It also quieted the van down and made it less stinky inside.

Exact reproduction parts are nice, but can be spendy. If I can solve a problem using materials that work just as well but are readily available and cheaper, then I will.

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Casually looking for a Clifford hyperpak intake for cheap.

I've done a few A-body heater boxes and used Detroit muscle technologies for the rebuild supplies which includes the "cord weatherstrip" you asked about. You can get it at home depot. I buy the 1/8" x 90' rolls made by M-D building products...item #71548. I also use it to secure the plastic moisture barrier behind the car door panels.

I like your suggestions, thanks boys. Will hit up the HD sometime today.

I was going to try and get away with re-using the original foam gaskets I had, but other than the thick black tubular foam gasket that circles the fan blower motor, all my other gaskets are toasty and crusty, especially the big circular gasket that seals the fresh air vent to the outlet under the top of the dash. I'm a little tired of the stink from leaks in the firewall!

My results from both Home Depot and Lowes were disappointing.

I was able to pick up a box of that 1/8" weatherstripping from Lowes. But they have no foam gasket material of any thickness in sheet form. They only have rolls of the stuff in narrow 1" widths.

If you look at the dampers that direct the airflow within the box, they are covered with a thin grey open-cell foam that's form-cut to the door's shapes to create a good seal. I would like to re-create these, but I would require a sheet of that foam material in order to do it.

I ended up ordering the DMT kit as it contains quite a few seals I need to create and this is too convenient to pass up so while I'll have that, I still need a solution for the interior doors.

Anyone have any idea where to conveniently buy this material?

Detroit Muscle kit will have all the door foam pre cut that is required. I got a kit from them in 08, and rebuilt my box. The project went quickly, and has been working flawlessly since.

One tip, and perhaps you have already done it is to clean/ derust and paint any surface that looks to be a bit degraded on the box, doors, and internal flappers. Use a high grade spray on contact cement such as 3M high hold.

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67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

When I resealed the HVAC system on my brother's van, I replaced this dried up foam on the air blend door with carefully placed and cut strips of the Home Depot weatherstripping. It has worked great ever since.

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Casually looking for a Clifford hyperpak intake for cheap.

Thanks guys. Corrected my order with DMT and ordered the heater box resto kit.

@Reed - good idea. I guess I could do that to save a few bucks but don't have the patience to cut all the strips to the required sizes. Convenience outweighed cost here, and I admire the DMT guys for having this kit available. Like to supporting the small biznesses.

Just wanted to give a shout-out to Jim and Loretta Fillmore, the team behind DMT. We had to work a little bit to get the right kit with all the right diverter door foams and box backing, but once we did, their kit was exactly the right thing for my heater box. Theirs is a great product, and I would heartily recommend it to anyone looking to rebuild their heater box. Beats the pants off of any 'makeshift' repairs I would have done.

When I rebuilt the heater box on the 83 D150 I bought bulk product from these folks and then cut it to fit,, using the OE gaskets as masters...

http://www.thefoamfactory.com/

I used closed cell 1/16 in thick neoprene on the internal doors and
open cell acoustic foam to remake the seals that are used where the ducting connects to the heater box..and the dash vents
as that is what the OE gaskets most closly resembled,, 3M foam adhesive to mount it ,,,

ditto on the products from dmt. my valve cover is clean as can be. i will buy any gasket i need from them from now on. only slightly higher than the chinese crap at o'reilly's, but it WORKS and its made here. the people were nice, too.