Cowl rust surgery, like to get some opinions

[BASE]

I've got the front of the truck stripped and was really just planning on repainting the firewall before dropping the new engine/drivetrain in. I told myself I was going to stay away from bodywork on this one, but I guess I should probably fix this while it's already tore apart.

It has some pretty minor rocker panel, floor and kick panel issues. I think I have a handle on how to address those. While I was cleaning up the firewall I found some more rust peeking through around the heater hole. Surprisingly the lower cowl sections are really solid.

I think there is a trough or gutter behind this as well as some sort of bracket for the mount. I was going to cut a small amount of metal out where the rust is peaking through, but now I'm starting to wonder if that would just be a waste of time. I don't know that I'd be able to get in there and do any good for the sheetmetal behind it. I'm also wondering if keeping it in one large piece would make it easier to repair and reinstall. Would taking the whole side of the cowl off be overkill?

My first thought was cutting something similar to the red line in the second picture. that might be pretty optimistic. Last pic is what I'm thinking might be better.

[71gmcC15]

That's the one spot mine don't have rust. Shure my roof and floor are shot but I got a good fire wall. Lol

[68 C10 Driver]

I would only cut out the smaller area you show in the second photo, then it would open things up so you can do a visual assessment. I am willing to bet you will be fine with the smaller section replaced. Be sure to treat the inside of the cowl area with something like Rust Mort to stop any surface rust inside the cowl from getting worse.

I had to do a little surgery in my cowl area on the driver's side. Once the rust was treated and primered, I applied a coat of Raptor Liner to completely seal off the cowl and prevent any future rust.

[BASE]

Yeah I was really kinda surprised to find that there. The lower cowls are really solid. Just a little rust on the rail of the rocker where the lower weatherstrip goes, and a bit at the floor to kick panel seams.

I found another thread where someone did more extensive surgery http://67-72chevytrucks.com/vboard/s...d.php?t=329483

After looking through that one and seeing what the inside structure looks like, I think I should probably just pull the outbd section off and deal with it. There is no way I'll be able to clean all that crap in there up well enough through a small hole in the front.

I bought this truck because it seemed really solid, and I didn't want to do any bodywork. I've only attempted this kind of thing once before and it was a disaster. Praying this one comes out better.

[sick472]

I'd cut the small portion out since it really needs to be replaced anyhow. Use that hole to inspect further and cut more out if needed.

[BASE]

Originally Posted by 68 C10 Driver

I would only cut out the smaller area you show in the second photo, then it would open things up so you can do a visual assessment. I am willing to bet you will be fine with the smaller section replaced. Be sure to treat the inside of the cowl area with something like Rust Mort to stop any surface rust inside the cowl from getting worse.

I had to do a little surgery in my cowl area on the driver's side. Once the rust was treated and primered, I applied a coat of Raptor Liner to completely seal off the cowl and prevent any future rust.

I had just about talked myself into taking the larger section off. I will cut the clearly bad stuff out and reassess this evening. I'm still not 100% on how that mount bracket and gutter are attached. I'm thinking the mount is welded to the cowl only, the gutter welded to the inner cowl and then spot welded to the outer after its installed. The gutter looks like a rusty mess from what I can see through the holes. I guess as long as I can find some good metal to weld the patch to.

[68 C10 Driver]

Be sure to remove that small area by cutting the spot welds first. You do not want to distort or rip the metal attached to the metal you are removing.

Good luck, looks daunting, but it will be an easy fix...just take your timer and as many breaks as you need to keep your composure.

[cj847]

I thought I had bought a pretty good 67 C10. It has rusty floor boards but no rust thru. However, when I figured out where the water came from that created that rust, I found some stuff similar to yours.

Go inside the cab behind and above the glovebox and pull the insulation off. I hope you don't find what I found. The circled items are holes (after I scrapped the area).

To seal this seam back up, I cut a hole in the upper cowl panel. Here it is with temporary tape on the seam. I haven't even dealt with the little rust spot you are looking at, but I have it as well. Good luck.

[BASE]

Originally Posted by cj847

I thought I had bought a pretty good 67 C10. It has rusty floor boards but no rust thru. However, when I figured out where the water came from that created that rust, I found some stuff similar to yours.

Go inside the cab behind and above the glovebox and pull the insulation off. I hope you don't find what I found. The circled items are holes (after I scrapped the area).

To seal this seam back up, I cut a hole in the upper cowl panel. Here it is with temporary tape on the seam. I haven't even dealt with the little rust spot you are looking at, but I have it as well. Good luck.

Yikes. Yeah that's what I'm afraid of. Or afraid of happening if I don't take care of this. Everything I can see and feel seems pretty solid but I will check inside.

I did get a smaller chunk cut out and poked around a bit. The metal behind looked pretty rotten but actually cleaned up with quite a bit of thickness left. Seems like the way it was put together is just asking for problems.

Anyhow, good call on taking the smaller chunk first. I just need to go scrounge up some sheetmetal and start putting it back together.

[BASE]

Gonna call it a day I guess. I'm pretty happy it wasn't any worse inside. I got the patch piece made, cleaned everything up the best I could and squirted some zink primer on the metal I won't be able to get to later. Thanks all for the advice, glad I didn't cut the whole end off now.

[Jason Banks]

I see I'm late to answer. I took the whole outer cowl off drilling all the spot welds and sand blasted both sides



Removing it revealed other things...

[May70]

Check my thread link below "Project Montezuma"

Just now doing this myself - although im closing it off for vintage air it might give you some insight as to what is back there.

Ill probably highlight it in my next youtube vid. Let me know if you have any questions

[BASE]

Originally Posted by Jason Banks

I see I'm late to answer. I took the whole outer cowl off drilling all the spot welds and sand blasted both sides



Removing it revealed other things...

Yeah I am sure there is more under there that could stand to be blasted/treated. I sometimes struggle with where to stop on this stuff. Hopefully this will buy me a few more years. I'm going to try and get some epoxy primer down in there and then seal it with seam sealer from the top best I can. The way it's put together it kind of funnels water down between the 2 layers.

Cowl screens are going in when I get this thing put back together. Something I should have done a long time ago.

[BASE]

Originally Posted by May70

Check my thread link below "Project Montezuma"

Just now doing this myself - although im closing it off for vintage air it might give you some insight as to what is back there.

Ill probably highlight it in my next youtube vid. Let me know if you have any questions

That is a great thread. I looked all over for pictures of the inside of that thing but never found yours. I love the detail on the rockers/floor/kickpanel areas. Those are up next for me.

[Jason Banks]

The good news is, that metal underneath the outer skin is all much thicker.

Here's a picture of my epoxied cab with the outer cowl removed
[IMG][/IMG]

[BASE]

The cowl is pretty thin stuff. It looks like around 20 gauge where I have it chopped up. I have a new(er) mig welder I'm just getting acquainted with, hopefully I won't vaporize what's left of it.

[Jason Banks]

I had several places where I cut out a chunk and went to weld in the patch and ended up cutting out a larger piece and making a new patch, because what I was trying to weld to was so thin from unseen rust.

[May70]

Here are some more pics

That rust spot I found was under the blower intake and I didnt know it until I blasted it from the cowl side. Couldnt tell from under the dash.