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Cowl rust pictures, what to do?


JMortensen

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I had seen that the seam sealer under the dash was cracking some years back when I did a repair under there, probably my clutch master replacement. Anyway, I have the car on the rotisserie now and I wanted to get in there and see what was up. Pulled the dash and scraped away some seam sealer and found some rust. It's really localized in the seam between the firewall and the cowl. My basic plan is to spin it upside down and spray some Zero Rust in there and hope that it seeps down in and gets everything, but I thought I would ask here and see if anyone has a better idea for me.

cowlrust1.jpg

cowlrust2.jpg

cowlrust3.jpg

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Can you drill your own inspection hole in a place to better access the rust below the seam. You could later plug the hole with a rubber grommet like Datsun used to plug drain holes. If you could gain access at a better location, you cold "osphos" the rust followed by a good water rinse and paint it. The "osphos" requires a thourogh rinsing as you know. EDITIF I am OFF on the photo.....soak the seam with Osphos and then water. A little soap if compatiable with the "osphos" woll penetrate better . Fireman use "wetter water" that contains soap for better penetration

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That one picture looks like pretty serious rust, in fact it looks like it's rotted all the way through the firewall. . Mine was about that bad and I ended up cutting it out and fabbing replacement patches. If only the design guys had made the panel roll up a couple inches so the seam wasn't on the bottom...

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That one picture looks like pretty serious rust, in fact it looks like it's rotted all the way through the firewall. . Mine was about that bad and I ended up cutting it out and fabbing replacement patches. If only the design guys had made the panel roll up a couple inches so the seam wasn't on the bottom...

Nope. Not rotted through. What you see in the seam there is not the other side, it's the seam sealer that I was unable to pick out of there. So it isn't quite a hole to the other side. I'll take some pics of the cowl area on top and see what that looks like. Hard to see into some of those areas, but the camera should fit right in there.

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john i had something very very similar to what you have.

 

I brushed out as much of the rust from the seams as i could both under dash and in the cowl, then used some naval jelly to dissolve the rust a bit. After cleaning I coated everythign with a VERY VERY heavy coat of ZeroRust inside the cowl, I brushed it on, it literally took a day to dry.

 

After that i put seam sealer along the seam from the inside and on the outside in the cowl as well. I applied the seal sealer thick. After that I gave everythig na heavy shot of primer and painted it. 3M makes a great seam sealer that dries fast and is easy to work with.

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jon:

How far apart are you planning to take the car? You stated that it is on a rotisserie so I assume it's disassembled to some degree. Having been a body man for over twenty five years, I would want to sand blast it. I remember from that other rust thread you have some experience with sand blasting, so I'm assuming you are trying to avoid having to do that. (I'm doing a lot of assuming aren't I?)

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It's pretty disassembled right now. The only things on it are the front and rear crossmembers and control arms. Everything else is off. The problem with sandblasting is that I have a pretty small garage, and I don't want sand in every little nook and cranny in the garage. Also the garage is on a hill and the concrete is not smooth so I can't really roll the car out, blast it, then roll it back in. I really don't want to sandblast if I don't have to. I have basically scraped and picked as much of the sealer out on one side as I could. Today the plan is to do the other side, then I was thinking about hitting it with a grinder with a wire wheel. I got a new wire wheel that has smaller knots that I think might get in there pretty good.

 

Anyway, you'd sand blast it. Then what?

 

I have Zero Rust, and I can go get naval jelly. I also have a lot of scrap sheet metal, but since there aren't any real holes I'm hoping to avoid any metal work if possible.

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Jon... I have been using my left over POR 15 "osphos" which goes a long way and does rapid rust conversion. The "osphos" is avaiable at most paint stores at less cost than the POr 15 variety. IN a spray bottle this rust converter will penetrate better than Naval Jelly which has probably the same chemical but in Jelly form.One problem is that the rust conversion require thorough water rinsing as does the naval jelly. POR 15 paint is crap but not their rust converter.Seam welding may seal the rust below and help preventing it's spread. "Osphos" is my way of identifing the rust converter for lack of a better word that I can't remember

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Thanks, Larry. I'm looking particularly for something that will penetrate.

 

I also have some Picklex20, which is thin and I think will penetrate too. It doesn't coat though. It stops the rust, but doesn't convert it into any kind of sealed coating. You can weld right through the new surface, and it is supposed to improve weld strength.

 

About the Ospho or naval jelly... can you weld to the surface after you treat it, or do you then have to wire wheel it, basically removing the coating, then weld it. That would seem backasswards if you had to do it that way.

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Well the other option is to bend up a couple of angles of sheet and attach to the good metal away from the rust. I did stitch some mildly rusty areas in the back of the car with pretty good luck and not too many blow throughs. I kind of focused in on the bad area. Around that one spot the rust is pretty light. I have my strut tower bars connecting in there so I would like it to have SOME strength...

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If there is a structural problem involved I'd attend to that first, maybe put in some bracing or whatever to compensate for any weakened metal.

 

Then I'd get a rust proofing wand spray gun arrangement, one with a flexible wand that enables you to spray into box sections and out of sight crevices. With mine Fishoilene was sprayed into all those sorts of places during the rebuild. You may not have that in the US, its an anti rust penetrating mineral turpentine soluble clear coating that remains tacky for a long time after application. Whatever, you know what I'm getting at, something that goes over rust, neutralises it and prevents further rusting.

 

While your're at it, spray in the sills/rocker panels etc too, great fun, not :)

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If you have a Dremel they make little wire wheels that attach to them. I would try and wire wheel as much of that area as possible. Then try and stop any more rust with some type of treatment recommended here. Instead if welding in some angle iron, bend up some sheet metal and weld that in place over the rusted/treated area. I you can patch it with sheet metal on both sides and the area is well treated, I wouldn't give it another thought.

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Well after several more hours in the garage I have more pictures:

 

cowlrust4.jpg

cowlrust5.jpg

cowlrust6.jpg

cowlrust7.jpg

cowlrust8.jpg

cowlrust9.jpg

cowlrust10.jpg

 

I scraped all the seam sealer out of the other side under the dash. That was the easy part. Then I looked in the cowl. I could see that there were a couple of big tarry globs in there. Everywhere there was a big tarry glob of crap, there was rust. Remember that area around the cowl vent that was all rusty? On the other side was a gigantic glob of tar that was about 1" deep and went all the way across the vent on the firewall side. It was REALLY hard to get off, but I did.

 

So now I think the plan is to start with some Picklex20 to neutralize the rust. Weld in angle sheet around the vent. Stitch the rest. Weld a plate to attach the strut tower bars to. Brush in the Zero Rust on both sides. That's pretty much it. I think that should be enough.

 

EDIT--Re seam seal the seam using Austin's 3M stuff.

 

I did figure out that one of my old strut tower bar mounts was connected to a vertical brace in the cowl. The other wasn't. You can see the outline where it was welded on in one of the above pics. Oops. Well I guess I'm learning about all of my previous mistakes.

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Experiment and try welding the seam first. Usually the light rust comes off. You will know right away if there is any rust getting in the weld.Looks like minimal rust to me on a northwest car. My Tomahawk project had Zero rust with a little corrosion under the battery box and the 250 GTO had surface rust on the rear tailight panel and the outside of the radiator support. I lived in Iowa 2 years and was told if you get it sealed from air the rust is slow to spread............................................................................. LOL I just remembered. I started with a wire brush and was not making much progress as the evening ended, so I squirted Osphos over the rust. The next day, I rinsed it off with water and the rust was gone. I hit it with a wire brush attached to the Makita to clean up a few flakey spots of the converted rust. It is probaly going to be more difficult to remove the temporary green garage sale rattle can paint at primer time

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Weird. I thought I replied and its not here.

 

Anyway, I did a little research on Ospho and Picklex20 and it turns out they have the same active ingredient, phosphoric acid. The Picklex is less concentrated so it doesn't have to be washed off and it's thin. This is nice for me since the car isn't getting out of the garage until it's off the rotisserie and the thin liquid should get into the crevices better.

 

Rufus, I'd love to sandblast it but I really don't want to do that in the garage. A friend of mine blasted a long joint where he was welding a trunk on his 510 and sand was forever in everything in the garage. Even today a couple years later you can move crates or boxes and there is sand outline around everything. I have my entire drivetrain in the garage, not to mention all of my tools. Just don't want to risk it.

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Just did the Picklex thing. A rotisserie sure helped here! Sprayed down the seam and brushed it in. Let it sit for about 5 minutes. Looked from underneath and sure enough you could see the Picklex coming through very nicely. Spun the car rightside up and hit the top side of the seam thoroughly. Made a paint brush extender so that I could brush it in all down the sides and in the corners. I think it's good to go as far as that's concerned. I'm going to let it dry overnight since it is 50º and raining here. Tomorrow, I will weld. The next day, paint in the Zero Rust.

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More progress. Had a little issue with the welder not feeding the wire correctly that delayed me for a day (details here: http://forums.hybridz.org/showthread.php?t=106934), then there was the holiday, but got back into it and made good progress yesterday and today.

 

I was in welding mode, so I kept going on all the seams that attach firewall to sides and the rocker seams as well. Got the right side all done, passenger side is tomorrow's project. Scraping the rockers clean of seam sealer is a real PITA for anyone who wants to attempt it. Heat it up with a heat gun, scrape it out with a screwdriver. Get the small stuff with a pick. Then hammer the flange until the gap between the floor and the rocker is gone, then you can weld it. I had scraped the seams a long time ago, and waited until it was on the rotisserie to weld them back together.

 

More pics:

cowlrust11.jpg

cowlrust12.jpg

cowlrust13.jpg

cowlrust14.jpg

stitchfirewall.jpg

stitchrocker.jpg

stitchrocker2.jpg

stitchrocker3.jpg

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