I'm in the process of replacing the heater core on my El Camino but ran into a snag.Theres a light coating of surface rust inside the heater box.I can reach some of it but there is no way to get at all of it.Is there something I can spray in there to neutralize this? I pulled out a large wad of leaves,padding and whatnot that covered about a 4x4 area of the box and cleaned up the heaviest rust spots there but I'm still left with this light surface rust inside.Any help or ideas is appreciated.

heater box is plastic except for the cover plate. take it apart and clean it out. reinstall.

I,m one of the few lucky people with an Elky ;)
that didn,t have original AC.Its definately metal.The underhood plate I cleaned up and painted with SEM gloss black. The underdash part is the one with the problem.TIA

Padding? Was a mouse living in it at some time? Car kind of smell a little inside? If answers are yes,then you have more work than some rust inside the plenum.

71, I bead blasted two, as far as the eye could see. I then sanded with a piece of sand paper as far as the fingers could reach. I then cleaned real good, ecth primed and painted. I have restore two and they both look real good. I don't think you will be able to get it all.

Rick, Definately no mice now maybe from anyone of 8 previous owners and the car only smells when I let one rip. :D It was the kind of stuff that falls down plenum and gets blown into a pile from the blower.The lite rust is probably from condensation from sitting under a car cover (no garage) all winter.
freddy,there's no way the heater will fit in my harbor freight blaster.
So basically I'm still looking for a spray or a liquid that can remove rust.Would muriatic acid work?

Do you have a Redi-Strip franchise near you? I would think that this part would be a perfect candidate for chemical dipping.

When I did my heater box, I cleaned out the surface rust as far as I could reach, and then used POR silver paint on the inside. It helps to use small mirrors to see the insides of the box.

Update.Finally realized that there was no way to get all the rust out so I used sandpaper stapled to a paint stirring stick to clean up as much as possible,then painted with rustoleum cold galvanizing paint on the inside only.The outside I primed and sprayed with semi flat krylon.Looks good and should provide some protection,I'll update in a couple of years or so. graemlins/clonk.gif