firewall rust solution - The 1947 - Present Chevrolet & GMC Truck Message Board Network

mentlmidget · 05-28-2011, 03:30 PM

86 c10. I took the factory air conditioning out to install aftermarket air (I could never get the air to blow really cold or in great abundance).
I have a rust problem on the firewall. Specifically as I can, I am talking about the cabs firewall meeting the vented cowl in front of the windshield. Water is going down the vented cowl and sitting where that panel is welded to the cab's firewall.
Any idea on how to fix that problem. It is not in one location. It appears to be along the entire firewall. It isn't too bad right now, but it will be a major problem in a few years I'll bet.
Suggestions please.

AlaskaChevy1 · 05-29-2011, 04:57 AM

I know exactly what your talking about. my truck is pretty rust free, but it sat for years. after getting back on the road i noticd it after rain, would drip water on the interior floor. after searching, found the culprit. rust exactly where describe- and a couple small holes on the inside of the firewall and bubbles in the engine compartment...i have not addressed mine yet, BUT plan on cleaning out as best i can with a wire brush and useing POR-15 products to clean and paint/seal the areas. then i also thought maybe of adding a couple new drain holes to help... it is an unusual spot to work on but needs to be addressed- good luck!

James McClure · 05-29-2011, 07:00 AM

Don't use a wire brush to remove rust. All this does is polish the rust. POR is an excellent product and works quite well IF YOU FOLLOW THE INSTRUCTIONS TO THE LETTER!! Mine same way. During restore it was fiberglassed along with the lower windshield flange. The area is fairly well hidden so you don't have to worry about perfection. Grind the area or sandblast, let it sit overninght after you wash it out (POR needs a light rust patena to work well) POR it, prime while still a little tacky then let dry all day,fiber glass, then paint. About 4 years on mine now and it's still good. jim

mentlmidget · 05-29-2011, 11:35 PM

Thanks guys.

ozark · 05-30-2011, 12:40 AM

I was lucky on my repair. I had a small hole that went to the inside with a larger section to the outside of the seam, I cut the rust out with wire cutters and sanded and scraped. I dug out the old seam sealer and covered the holes with duct tape. I then filled the seam backup with new seam sealer. When it set up I removed the duct tape and sprayed the seam in the engine bay with undercoating like the factory and spary painted the cowl area the color of my truck. Hopefully this will hold up.

05-28-2011, 03:30 PM	#1
mentlmidget Registered User Join Date: Jun 2005 Location: Fort Lauderdale, FL Posts: 30	firewall rust solution 86 c10. I took the factory air conditioning out to install aftermarket air (I could never get the air to blow really cold or in great abundance). I have a rust problem on the firewall. Specifically as I can, I am talking about the cabs firewall meeting the vented cowl in front of the windshield. Water is going down the vented cowl and sitting where that panel is welded to the cab's firewall. Any idea on how to fix that problem. It is not in one location. It appears to be along the entire firewall. It isn't too bad right now, but it will be a major problem in a few years I'll bet. Suggestions please.

05-29-2011, 04:57 AM	#2
AlaskaChevy1 Registered User Join Date: Jul 2007 Location: Anchorage,Alaska Posts: 14	Re: firewall rust solution I know exactly what your talking about. my truck is pretty rust free, but it sat for years. after getting back on the road i noticd it after rain, would drip water on the interior floor. after searching, found the culprit. rust exactly where describe- and a couple small holes on the inside of the firewall and bubbles in the engine compartment...i have not addressed mine yet, BUT plan on cleaning out as best i can with a wire brush and useing POR-15 products to clean and paint/seal the areas. then i also thought maybe of adding a couple new drain holes to help... it is an unusual spot to work on but needs to be addressed- good luck! __________________ 1976 SWB 350/350 2WD

05-29-2011, 07:00 AM	#3
James McClure One shot, one kill. Join Date: Dec 2007 Location: Saratoga Springs NY Posts: 859	Re: firewall rust solution Don't use a wire brush to remove rust. All this does is polish the rust. POR is an excellent product and works quite well IF YOU FOLLOW THE INSTRUCTIONS TO THE LETTER!! Mine same way. During restore it was fiberglassed along with the lower windshield flange. The area is fairly well hidden so you don't have to worry about perfection. Grind the area or sandblast, let it sit overninght after you wash it out (POR needs a light rust patena to work well) POR it, prime while still a little tacky then let dry all day,fiber glass, then paint. About 4 years on mine now and it's still good. jim __________________ 1984 K20 350M engine with 465,000 miles. Well, it's finally done!! Almost 2 years of work, but it was really worth the effort. Little stuff left to do is mount winch, wet sand & buff out and build belly pan\running boards. Body work takes lots and LOTS of beer!!!! God, Guts and Guns made America and God, Guts and Guns will preserve it! The worst thing you could do is get into my sights, but that don't matter, you'll never know it, cause you'll never hear the shotJim or Paladin whichever you choose.

05-29-2011, 11:35 PM	#4
mentlmidget Registered User Join Date: Jun 2005 Location: Fort Lauderdale, FL Posts: 30	Re: firewall rust solution Thanks guys.

05-30-2011, 12:40 AM	#5
ozark Registered User Join Date: Jan 2008 Location: Eureka Springs AR Posts: 179	Re: firewall rust solution I was lucky on my repair. I had a small hole that went to the inside with a larger section to the outside of the seam, I cut the rust out with wire cutters and sanded and scraped. I dug out the old seam sealer and covered the holes with duct tape. I then filled the seam backup with new seam sealer. When it set up I removed the duct tape and sprayed the seam in the engine bay with undercoating like the factory and spary painted the cowl area the color of my truck. Hopefully this will hold up.



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