What causes this rust spot on the firewall?

WissaMan

Well-Known Member
Joined
Sep 12, 2018
Messages
575
Reaction score
597
Location
Northeast PA, 10 minutes from Knoebels Grove
Although I can see inside the car through this rust hole, it doesn't open up directly to the other side. Does the cowl drain down past this spot? This is a 68 Newport

upload_2021-3-14_19-52-38.png
 
Very common problem on '65-'68 C bodies.

Yes, water that comes in through the cowl vent comes past that spot. Usually when it has rusted through, the cause was a build up of leaves and or dirt in the cowl.

Jeff
 
Very common problem on '65-'68 C bodies.

Yes, water that comes in through the cowl vent comes past that spot. Usually when it has rusted through, the cause was a build up of leaves and or dirt in the cowl.

Jeff

Does this mean there is still debris in the vent? Is there a way to clean it out without removing the HVAC system? I have the same issue on my 67' Imperial.
 
Does this mean there is still debris in the vent? Is there a way to clean it out without removing the HVAC system? I have the same issue on my 67' Imperial.

The best approach would be to remove the cowl panel and spray the inside with a hose. It takes about a half hour or so to remove the cowl panel.

Jeff
 
When I look up under the dash I can see the firewall on the interior-side doesn't look like it was painted at all so I wonder if these spots got much paint, if any.

After clearing the leaves and gunk, maybe something like this would be good insurance against future corrosion: Eastwood Internal Frame Coating Aerosol Spray (14-oz.) Though if there are already holes on the interior-side of the car, you could have a real mess on your hands if you don't mask them before spraying this stuff -- it's kind of runny, not sticky like undercoating spray...
 
As mentioned previously, My Polara had a crap load of leaves and dirt in the vent channels. I used a wire to help clean out from underneath even after vacuuming the vent channels out from top to bottom.
Not a problem anymore, I don't keep the car in a place where leaves can infiltrate as well as shooting some Rust check spray down each side.
 
Back
Top