I am replacing the evaporator on my 1985 F150. When I took the cover off the enclosure box (attached the the firewall), there was some sort of sticky glue or grease of some sort along the edge of the box and some on the evaporator itself. Is this supposed to be a gasket? The old evaporator itself was pretty nasty, so it is hard to tell. The evaporator enclosure box uses screws to attach the two halves together. Does the evaporator enclosure box supposed to be sealed with a gasket too?

 

You can use foam tape Just clean everything up real good.

 

Yep, that's what remains of the gasket after it disintegrates over the years. I just go to lowes or a hardware store and find some foam with the sticky on one side and use that. You could also probably use that gray rope putty.

 

Actually, I think the factory used some black rope putty for that instead of a foam gasket. Don't know why, but I've pulled several of them apart and it sure seems like the plumber's tape although it is black. But I like the foam approach and use that instead.

 

The grey rope putty melts, and plugs up the drain hole. Been there, tried that.

 

Thank you, gentlemen.

How thick of a gasket do I need? And why does the enclosure box even need a gasket?

 

Depends somewhat on how firm the stuff is. IIRC, there is a lip on the outside of the box that hits first, but then an opening inside of that that is 1/8 - 3/16" wide. You need the foam to squish to that size w/o too much pressure. So something like 3/8" thick should be good.

And, the enclosure box will leak part of your air into the engine compartment w/o the gasket.

 

Since you have the 1980/89 Ford Light Truck Parts Catalog: Look here: Illustration 195 .. Page 8.

Why did you buy this catalog, if you aren't going to use it? With this catalog, you can answer your own questions. How many answers have you received so far?

Two One says remains of a foam gasket, t'other says black rope-a-dope putty = what's called dum-dum in the biz. Individual pieces look like licorice sticks, don't taste the same.

Available from automotive paint supply stores.

 

Parts stores that deal in mobile HVAC supplies have the rolls of dum-dum or evaporator tape as it is called by some vendors. It is a sticky nasty 25' roll. I would go back in with the foam. 1/8" should suffice. Newer vehicles have gone to the foam.