Sealant on firewall at A C evaporator

[John M.]

Does anyone have images of the sealant sprayed to seal the evaporator housing to the firewall? Or perhaps they used the same method and material for the outside heater box where it is held against the engine side of the firewall? I would think that G M would have certainly used a sealer at this joint but have not seen detailed enough photos to see how much and what type. Also interested in knowing what you have used to replicate the firewall sealer used in St. Louis. Those of you fortunate to have unrestored cars have any photos of this area? Thanks in advance for ahy information or images you may provide.

[Rocco S.]

Re: Sealant on firewall at A C evaporator

John,
I am not sure if this will help but these are photos of my unrestored 1967 St. Louis coupe with L79 and A/C. Last year I did a heater core (not fun) and tried to leave the sealant intact. The sealant appears to have been sprayed on and has dried to a hard, brittle consistency.
Firewall Nut 1.jpgFirewall Nut 2.jpg

[Michael M.]

Re: Sealant on firewall at A C evaporator

The best product I have used is call submarine sealer. Not sure if it still available. You might want to try to google the product.

[John M.]

Re: Sealant on firewall at A C evaporator

Rocco and Michael, thanks for the response! Submarine sealer is in fact still available by mail from several places. Do you have a photo showing how it looks when applied to your car? How does it compare in appearance to the original sealant from GM. Rocco, would you be able to post some images from further away from the case so look of the application and overlap ammount can be seen? Thanks in advance.

[Michael M.]

Re: Sealant on firewall at A C evaporator

John, it looks like the picture Rocco posted. If you order the submarine sealer you can spray a test panel to see if it meets your satisfaction.

[Rocco S.]

Re: Sealant on firewall at A C evaporator

John, Here's a few more photos of the firewall. I hope this helps.
Firewall 1.jpgFirewall 2.jpgFirewall 3.jpg

[John M.]

Re: Sealant on firewall at A C evaporator

Rocco, thank you for the images of the perimeter of your A C unit. I ordered a quart of Submarine Sealant and it will arrive no sooner than the 13th of July, so leaving the engine out until then for access to the affected area. Now to devise a method of application that replicates your pictures. So far no method in mind. since I have no idea of the viscosity of the sealer. If any of you have applied this sealer to your satisfaction please share your knowledge. Again, thanks for your help!

[Michael M.]

Re: Sealant on firewall at A C evaporator

John, when I used the submarine sealer I purchased the product in a spray can. Hence, just spraying it on like the factory did. When you find out the viscosity of the sealer I am sure you can spray it on. I would not reduce the product, but you might need a bigger tip on your spray gun.

[John M.]

Re: Sealant on firewall at A C evaporator

Used the Submarine sealer, applied with an old large broken screwdriver, sort of shoveled it on and it flowed out well. Was brown when first applied but the next day it was black and had a semi gloss sheen very much as the factory sealer had when new. I was very pleased with the outcome! Still have most of the quart left. The thickness of the non spray can material would never be able to be thinned enough to spray, in fact the instructions say never to thin with anything. I was surprised how well it flowed and was self leveling. Thanks for the information and suggesting this product.