1985 C/10 Firewall question

[65standard]

Is this black sprayed on sealant on the firewall factory installed? It is an ugly mess. I started to clean some of it off.

[Hiluxxulih]

Its factory my 85 has it too , I think its to keep water out of those seams .

[11555wally]

My 86 has that as well. Not as much as yours though. How are you getting it off?

[Gmc.guy]

A scraper and a small propane torch to soften it up works well, then a rag and acetone lawyer thinner or gas takes the film off. There really isn't a way to do it easy. The brake booster area is a pain this truck of my dads I sept many hours on it and it come out nice

[Gmc.guy]

This truck had 1:4 inch of yellow Tremclad on top too This is halfway done

[Gmc.guy]

This ones halfway

[gmachinz]

Looks good so far! Them factory pinch welded seams are terrible-I ended up reapplying some 3M undercoating to mine but I did a much cleaner job that OEM factory. I masked it off really nice and then spray seal the seams.

[Big Blue]

Sorry for stealing the topic, just trying to find an answer,,,GMC Guy, I sent you a PM, and asked the question ,what wire came out of the ( BLACK CIRCLE ) This is the wire that goes through the firewall. What are they for?

Thanks for any help, John

[Gmc.guy]

Ok. I replied but I thought you meant where the red circle is. I cannot remember but I'll look thru my pics and see what I can come up with.

[65standard]

The gooey yellow stuff is coming off. The black tar crap is hard and crispy. I'll remove it all and just use body seam sealer very carefully. I'm not doing a restoration job, just wanted to clean it up some for my LSx swap.

[Gmc.guy]

I have some parts trucks that might be intact there I'll take a look too. Maybe oil pressure switch ?

[Gmc.guy]

Originally Posted by 65standard

The gooey yellow stuff is coming off. The black tar crap is hard and crispy. I'll remove it all and just use body seam sealer very carefully. I'm not doing a restoration job, just wanted to clean it up some for my LSx swap.

This one was fairly crispy too. It softens up still with heat. Not good if you want to keep your paint. I'd try penetrating oil and solvents. We are trying to figure what to seal it back up or if we should just leave it? We don't want to spay black gunk on nice polished blue paint

[65standard]

Big blue, I don't have any wire coming from that hole in the black circle. There is a bolt in it.

[Gmc.guy]

Also for big blue , this is an old blazer tub I have. It has that wire it is clipped at the boot but looks like it spliced to a wire poking out the harness that goes to the vacuum thing above the booster there. The boot/plug on this one looks larger than yours, is yours a black with white stripe? Sorry to plug your thread up man. We went a different direction on ya there

[gmachinz]

That's where the factory tach wire grommet goes I'm pretty sure. Its a 1" diameter hole iirc.

[Big Blue]

Thanks everyone, I am not using the tbi/computer in this build so maybe I do not need this wire. I posted this in electrical but got NO ANSWERS at all. So I am very sorry for stealing your topic. Carry on............



John

[hotrodder]

My 85 has a very small amount , nothing like the pictures some have.

[1970pelle]

The cab seam that has all the black undercoat is the cowl box seal/weld. Take your cowl panel off and look down inside and you will see the seam. When new it had gray or yellow body seam sealer in that fold/seam. I found on my truck the seam sealer had aged and dried up and cracked. And wasn't doing its job anymore. That's the cause of rusted fire walls in that seam area.
I dug what I could of the old seam sealer and resealed with seam sealer. Which old body shop guys would call it Stop Check Sealer, Seam Sealer. It comes in a calk gun style tube, gt cans, sqweese tubes. I like NAPA Martin Senour products.

So even when cleaning it off on the outside of the cab, in the engine bay. I would still seal that seam. Water will still find its way up through the very small open area's. But we have much more patients when doing things than the auto workers back in the day.

[N2TRUX]

That topic came up recently on Facebook, and yes its factory. I am trying to remove or minimize whats there on my 84 Sierra and keep the paint intact.

So heat and solvent are the best solution so far? Anyone else got a home brew that works better?

[1970pelle]

I used white Kerosene on the engine bay black stuff. I soaked it, then removed first layer of softened dull putty knife. The rest with Harbor Freight white rags. There reds rags bleed the dye all over with any kind of cleaning solvent. Then hot dish soap wash.



Ken

[CSHADES]

The big hole is for the wiring from ESC dist and back to the module. I cut a plug and welded it shut.

[N2TRUX]

Originally Posted by 1970pelle

I used white Kerosene on the engine bay black stuff. I soaked it, then removed first layer of softened dull putty knife. The rest with Harbor Freight white rags. There reds rags bleed the dye all over with any kind of cleaning solvent. Then hot dish soap wash.

Ken

Excellent info. I know it is petroleum based, so its just a matter of what solvent will break it down without hurting the paint. I have some cheap white micro fiber towels that I will use for clean up.

[1970pelle]

when I lived in North East Ohio after the 6 month winters of ice and snow. Plus all the road salt and ash they would spread all over the place. The outside along with the underside of our vehicles took a beating. We stored our nicest vehicles for the summer months.
But after winter broke, we would wash our cars/trucks, then rub them down with Kerosene. I mean go crazy with the stuff wipe everything you could. Then wash the whole car/truck again with Hot soapy water. It would come with the paint felling like sand paper. Then we would wax them and then seal them. They then looked and shined like glass. The Kerosene cut all the road grime and stuff that had embedded it's self into the paint.


Ken

[65standard]

This 1984 4x4 has that plug on the firewall with two green wires coming out and run down along the frame towards the rear. Can't be for the tach or computer as this truck has no tach.

[Chevy_mud_truck]

Back up lights for a manual transmission