Cowl Rust Repair Options

[Jim70Chevy]

As I am tearing down my front end to clean things up and repair rust I am finding the common rust issues inside the cowl (and leaking in the cab).

I have done a bunch of reading of threads and builds here but not been able to find the answer to the following question.

Can I cut a hole in the outer panel (as shown by red line in picture) to fix the rust and make my repairs then weld the panel back into place?

I am trying to avoid having to replace the whole cowl piece but that may be the only answer.

Thank you in advance for your thoughts.

Jim

[Longhornss]

Yes.
It sure is possible to repair the area by boing that. I would suggest removing the spit welds and cutting the vowel closer to the vent opening to minimize the amount of straight line welding you will have.
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[swamp rat]

You can do that, or you can get a spot weld drill and drill all the spot welds and cut the cowl up at the top opening, or remove the whole cowl, chances are that some of the inner cab seams that are rusting out and leaking into the cab are going to be better accessed, you already have some home made brackets that are holding it together it looks like. There are also repro outer cowls available if necessary.

Here's a thread that helps show the inner workings of the cab, scroll down to post 15 and it will show you how the cab is put together under the outer cowl.

http://67-72chevytrucks.com/vboard/s...d.php?t=705214

[Longhornss]

Here is the repair I did to my my truck

[Jim70Chevy]

Longhorns thank you for the pics and Swamprat thank you for the link. That helps a lot.

I have ordered a spot weld drill bit. I am sure I am going to need it in this build.

[Jim70Chevy]

Swamprat - What a great build thread that is. I am so glad I don't have to go that deep into this. That's a crazy amount of work but it is the perfect thread for cowl repair. Post 78 is an inspiration.

Thanks again guys.

[Jim70Chevy]

I got the area cut away and exposed. After some rust cleaning I can see that there are some areas that need repair. I was thinking that I might cut out and patch the seam area (shown on photo) and weld the smaller holes shut. Then use seam sealer on all edges and follow it up with Por15 on the hole panel.

Is this a good approach or do I need to do more?

Thanks in advance.

[LongBox]

Looks like you are doing great work on your truck, and things will be great when you're done. The basic design looks like it was done by GM on purpose to promote rust. If leaves, dust, etc get into the cowl area, they are going to end up down on the sides, where they will hold water and salt, and cause rust in the cab and fender. I try to wash mine down as often as possible, but the drain holes in the bottom of the fender area are pretty small, so leaves must get stuck in there.

Wonder if there's anything you can do while you are into it to prevent that in the future?

[sduckworth13]

Awesome!! The spot welds look great! Longhornss what kind of welder are you using?

[swamp rat]

The best thing to do is to cut out all the rust and weld in new metal.

I think the small holes are worse than you think, If you can take an ice pick and poke thru it with a moderate swing then it should be cut out and replaced, I use an old electrical test probe for checking, don't just push on the metal with the pick, give it a swing. I'd cut them out with a cutoff wheel back to solid metal and make patches, as for the area at the seam I think you may find that the area to be replaced may be larger than what's in the red, the seam looks to have rust in it all the way to the firewall.Be sure to treat the metal when your done with the repair, then seam seal everything.

[HO455]

Originally Posted by swamp rat

The best thing to do is to cut out all the rust and weld in new metal.

I think the small holes are worse than you think, If you can take an ice pick and poke thru it with a moderate swing then it should be cut out and replaced, I use an old electrical test probe for checking, don't just push on the metal with the pick, give it a swing. I'd cut them out with a cutoff wheel back to solid metal and make patches, as for the area at the seam I think you may find that the area to be replaced may be larger than what's in the red, the seam looks to have rust in it all the way to the firewall.Be sure to treat the metal when your done with the repair, then seam seal everything.

I agree with Swamp Rat. You will find it difficult to weld those holes up. It will be easier to cut and patch them.

[Jim70Chevy]

OK so cut and patch it is. Now I am trying to decide of I want to just eliminate the vents altogether. Sealing up and smoothing the cowl vents would look great but not sure I have the skills to do it. Need to do some more searching.

[Oldblue68chevy]

Looks like the same rust my cab had. I ended up removing the vents on my cab. When it was all said and done I had removed the dash to get at those pieces and to repair the area under the windsheild gasket. Its alot of work but if you take your time and just do small sections at time its fixable. You just dont want to leave any rust behind or youll be redoing the work in a year or two.

[swamp rat]

Well, I grew up with these trucks and i'll tell you the truth, I could not imagine not having the vents, there isn't any up on the dash and on a hot day the vents and wings are a saving grace.

Where the seam is you will be fine with a rectangular piece and just totally remove the seam, if you keep it about 1 1/4" wide it will be easy to bend it up as it go's toward the cab, just be sure to cut back to good weldable metal.

If I haven't said it already be sure to prime it up and seam seal all the welds, but before you do be sure to check the welds with a light and look for pin holes, if ya find then get the welder back out and fill them.

[Metaldoc]

Had the same thing it was swiss cheese. I made a new replacement from scratch. It was not easy but not impossible.

[Oldblue68chevy]

I guess I should have added I have an AC cab so removing the vents didn't concern me as much.

Metaldoc thats a hell of a panel you made there. I had a hell of a time just forming the flat pieces for my patch job.

Here are a few pics of what I was dealing with. Like I said one piece at a time.

[Jim70Chevy]

Wow, thanks. This was perfect. Put things in perspective for me. I have to remember that this is going to be a driver (so easy to get carried away) and even though I have an AC cab I probably wont have the AC running for a few years. Swamp Rat is right, I will want the fresh air.

Metaldoc - what a great panel you made. Very impressive. I am a beginner at best and that is out of my scope but very cool to see. Maybe you should manufacture those panels for sale. I would have bought one and I am guessing many other would too.

Oldblue - Thanks for the pics and advice. Nice work. I think I am going to stick to as close to stock for this part after all and just do some patching.

I will post pics as I go.

Thanks guys.

Jim

[Dustmaker65]

Metaldoc and Oldblue...you fellas are artists! Very nice work by both of you!

Jim70Chevy...I am in your class, slow and easy. But we will get done in good time too.

[Oldblue68chevy]

Thanks just one more piece of advise for when you get frustrated, just set the tools down and walk away for a day if you have to. It definitely doesnt get rebuilt overnight. Ive been working in my truck for 2 years it's finally driveable again but still needs alot of work.

[Longhornss]

Originally Posted by sduckworth13

Awesome!! The spot welds look great! Longhornss what kind of welder are you using?

This was welded using a Miller 110 volt welder. With the heat setting all the way up.

My pictures still show a fair amount of rust but rest assured all that metal was removed and replaced with fresh 19ga. Steel. In the pics you can see I removed the original kick panel vents and replaced them with speaker enclosures. I will be running a vintage air and keeping the vent windows, so I have no need for the vowel vents.

[Orange Crate]

Here is a link for the cowl screen install and sources.

http://67-72chevytrucks.com/vboard/s...d.php?t=553767

[swamp rat]

Originally Posted by Metaldoc

Had the same thing it was swiss cheese. I made a new replacement from scratch. It was not easy but not impossible.

I'' take 2 Right's and 2 Left's please... Dang I forgot about that on your build thread, did you show a step by step?

Sorry for asking on this thread.

[Metaldoc]

Originally Posted by swamp rat

I'' take 2 Right's and 2 Left's please... Dang I forgot about that on your build thread, did you show a step by step?

Sorry for asking on this thread.

I did show some pics on page 1 off my build but I do have more in detail pics if needed.