Cowl seam rust repair advice needed

Redbark · May 10, 2018

I'm doing a body off frame restoration of a 68 Bronco. There is evidence of surface rust in the cowl seam where the seam sealer failed. I think I know the answer to this but do I have any option to deal with this other than removing the cowl, exposing the rust and treating it mechanically or chemically?
Removing the cowl is a big job, a potential addition to an already very long list of jobs.

DirtDonk · May 10, 2018

It is a big job. And one that Doug had to do to my '68 when he was building it.
The biggest question for you initially I think, is whether or not the rust underneath is substantial enough to dictate removing the top and treating it directly or not.
In most cases, the answer has been yes, you MUST deal with it.

I'm not sure how much will show, but for sure if you can find rust-through underneath the dash where you can see it, then your decision has already been made for you.
What does the area around the steering column mounting under the dash look like? I was working on a friend's '68 one time and while fiddling with the column wiring put a screwdriver right through the inner cowl!
So yeah, in spite of his body actually looking really clean on top, it was just masking the demon underneath.

Any way to get an optical probe (whatever those things are called) through one of the openings at either end of the cowl under the hood there to see what there is to be seen in there without opening it up?
Might be an option anyway.

Good luck. Very high probability of more work ahead though, given it's a Bronco!%)

Paul

Rustytruck · May 10, 2018

Just depends on how far you want to go with it. I opened the ends of the channel and ran a long extended tube air hose and blew out the rusty crap. I then used east woods frame sealer with the extended hose and did several applications to seal it up. then re-welded the ends of the channel and used seam sealer again.

Redbark · May 10, 2018

DirtDonk said:
It is a big job. And one that Doug had to do to my '68 when he was building it.
The biggest question for you initially I think, is whether or not the rust underneath is substantial enough to dictate removing the top and treating it directly or not.
In most cases, the answer has been yes, you MUST deal with it.

I'm not sure how much will show, but for sure if you can find rust-through underneath the dash where you can see it, then your decision has already been made for you.
What does the area around the steering column mounting under the dash look like? I was working on a friend's '68 one time and while fiddling with the column wiring put a screwdriver right through the inner cowl!
So yeah, in spite of his body actually looking really clean on top, it was just masking the demon underneath.

Any way to get an optical probe (whatever those things are called) through one of the openings at either end of the cowl under the hood there to see what there is to be seen in there without opening it up?
Might be an option anyway.

Good luck. Very high probability of more work ahead though, given it's a Bronco!%)

Paul

There doesn't appear to be any rust through underneath, although there is surface rust. I think I need to dig deeper. I'll start by removing the passenger cowl and see where that takes me.

bronkenn · May 10, 2018

I did what Rusty did. Cleaned it out then put a rust (POR15) paint in it and closed the ends back up. If it feels solid from the outside then it should be fine. If a screwdriver goes through like Paul said than surgery will need to be performed. Ken

Redbark · May 10, 2018

bronkenn said:
I did what Rusty did. Cleaned it out then put a rust (POR15) paint in it and closed the ends back up. If it feels solid from the outside then it should be fine. If a screwdriver goes through like Paul said than surgery will need to be performed. Ken

What you're suggesting works for inside the channel, but it doesn't deal with the rust that exists along and inside the cowl seam as seen in the pics. To deal with the seam rust, would I not need to separate the seam to treat it?

suckerpunched · May 10, 2018

In my experience, POR15 creeps into seems like that really well. if you don't think the rust is severe enough to justify cutting it apart. POR15 the seam, seam seal it and prime. also I used a product in that area on mine that was a corrosion protector that came in a spray can with a about a 3 foot tube on it with a nozzle on the end. The product came out wet like oil but dried to a waxy coating. fed the tube in through a bolt hole, I think the hood hinge holes but can't remember for sure.

taipeichris · May 11, 2018

Hi,

In my experience, the small amount of visible rust on the outside of the cowl led to my pedal bracket breaking from the cowl while I was driving on the freeway shifting gears. Keep in mind both my clutch and brake pedal were attached to that bracket.

Replace it. Whatever it takes. Do it once and do it right, your life might depend on it.

PS And if you're thinking, how did he stop the Bronco on the freeway?

Not very well and I ended up rolling off the freeway into an embankment of bushes. Yep, never a dull moment in a 52 year old truck but I think it was only 46 at the time.

Redbark · May 19, 2018

Well, I pulled the cowl panels off and I'm glad I did. There is very heavy corrosion underneath the panels. The steering column mount area seems sound. There is no rust through anywhere, but the whole trough is heavily pitted. I'm going to have the tub media blasted so I'll get a better idea if any metal repair is required.

PilotTerry · May 10, 2022

taipeichris said:
Hi,

In my experience, the small amount of visible rust on the outside of the cowl led to my pedal bracket breaking from the cowl while I was driving on the freeway shifting gears. Keep in mind both my clutch and brake pedal were attached to that bracket.

Replace it. Whatever it takes. Do it once and do it right, your life might depend on it.

PS And if you're thinking, how did he stop the Bronco on the freeway?

Not very well and I ended up rolling off the freeway into an embankment of bushes. Yep, never a dull moment in a 52 year old truck but I think it was only 46 at the time.

Holy smokes - thanks for the advice! That's just a little scary... @taipeichris

DirtDonk · May 10, 2022

Yeah, a lot of them are misleading. But a lot of them are still intact as well.
So it really does take some detailed looking into. Not only from the top, but especially from underneath the dash poking around looking for any rust through spots that might be hidden from the top.
After all, when moisture gets in there it tends to sit on the bottom, which is the panel ("Penelope up top" from my phone?), underneath the dash.

Madgyver · May 12, 2022

you can do it... i salvaged this

Yeller · May 12, 2022

Madgyver said:
you can do it... i salvaged this

We call you Mad for a reason

..... Actually we all humbly hold you in high esteem for the stuff you salvage, it truly is incredible.

So I second yes, you can do it!

Cowl seam rust repair advice needed

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