Vintage Mustang Forums banner

1 - 20 of 46 Posts

·
Registered
Joined
·
1,178 Posts
Discussion Starter #1
I would like to preface this by saying I dont know how bad the driver's-side cowl is yet, have to pull that vent...but when I got the car that floor board was pretty badly rotted and I dont see much other source. I just finished replacing the floors driver and passenger(and lower angled portion of the firewall...floorpan extensions) due to rot on those pieces. So today I crawled under the dash on the passenger side and to my confusion the only rust I see around that vent is light surface rust on the underside(I suppose its possible that a heater core leak caused the rot on that side). With the driver side vent in place...I dont see any rot(again just surface rust) on the metal around it...but I do see darker rust peeking out from under the vent, so I assume that at the very least that collar is shot...which means that the cowl has to come off for at least minor repair which leads me to my question:

Should I:

A. Just buy a couple of patch panels and go that route?

B. Buy a lower cowl assembly and replace the lower cowl?

C. Buy the full upper and lower cowl and replace the whole thing?

From everything I have seen the Dynacorn assembly fits very well and I am not particularly worried about being able to fit the thing...its just that I dont want to ever have to repair the cowl again after this one time. Keep in mind that this car WILL be a daily driver for probably 200+ days a year...even though most of the time I will have a cowl cover on the thing anyway since I dont see the vents as particularly useful most of the time anyway.
 

·
Registered
Joined
·
214 Posts
First off, make sure you kow what's rusted and what's not. I assumed my cowl would be rusted out, at least the collars, since the floor pans had been replaced and there's a hole in the passenger side firewall extension. Turns out, the cowl and collars are just fine!! No rust holes at all, nice and solid. The heater hoses had been leaking. You can inspect almost 100% of the collars and cowl from below and the sides, if you have your fenders off. There are access holes, and a good flashlight helps. A video borescope helps even more.

So, if you need a collar repair set (plastic collars that get bonded in from inside the car), let me know, I have a set I won't need.
 

·
Registered
Joined
·
1,438 Posts
If you look up in the hole there look closely at the seam where the vertical pipe meets the cowl floor.

There's some seam sealer there that rots out and lets water seep through. If you run a hose on the cowl for a while you might see it getting damp. It'll take a few minutes since it's just seeping water instead of pouring through a hole, but that could be your problem and it's worth looking at before you start cutting things up.

Just one more thing to look at.
 

·
Registered
Joined
·
4,374 Posts
I guess the windshield frame isn't mentioned enough as a leak spot. THE WINDSHIELD SURROUND CAN RUST AND LEAK:grin2: Even leak without an extraneous hole then a hero squirts silicone around the seal and makes it worse. Top or bottom lengths can hold water when not driven.
After that spot is where the inner cowl meets the kick panel wall, it is spot welded and seem sealed. The sealer can fail and leak without making any actual new holes.

Some if not most can be repaired and treated to last another 50 years without major surgery. Search for Cowl Repair Hats and pick a seem sealer.
 

·
Registered
Joined
·
1,178 Posts
Discussion Starter #5
Well, I took the vent off and inspected the driver's side closer from underneath. There is no rot that I can see on the cowl panel itself...just minor surface rust(which tells me nothing about the other side of the panel, but the bottom side is good. As I suspected though, there is a lot of rust flaking from the cowl collar itself...I suspect its starting to rot. The main problem though is that I reached up into the collar and felt around and it seems like there about an inch or so of mulch from decomposing leaves and the like surrounding the collar holding moisture. So...I believe I can get away without any metal cowl repair at all...if I can somehow manage to remove all the mulch surrounding the collars and using one of those plastic collar repair kits...also keeping the cowl vent blocked off. Anyone have any tips on how to easily remove all the debris in there? My hands are large and while I may be able to grab a pinch at a time, that just doesn't seem like it will get it all. Its pretty damp so I doubt a vacuum will suck it up very well...but if I can find or make some sort of U shaped attachment I will try that method. Since I am sure that debris has been sitting there an causing surface rust and pitting on the top side of the panel, is there any way to get in there with a spray paint can and giving it some type of protective coat?

I just dont want to end up in a situation that the cowl will need repair AFTER I paint the car, so looking for the best path forward, even if that involves pulling off the upper cowl(only 200 spot welds right?)
 

·
Registered
Joined
·
1,178 Posts
Discussion Starter #7 (Edited)
Try a piece of PVC drain trap for the "U" shaped piece for your vacuum. I think what you'll find, though, are pinholes all along the "hat"....
You are probably right....best to pull the upper cowl and just patch the lower(or the collars, at the least) and be done with it...which leads back to the question of patch or replace...worried about having enough room for my MIG(or TIG, whichever method I choose to use there) torch inside the cowl to get a good bead laid down.(There might be plenty of room for all I know, but it seems pretty tight looking at it)

P.S. What kind of time am I looking out for a cowl repair without major rust?
 

·
Registered
Joined
·
571 Posts
you can cut into the top cowl piece near the drain on both sides and bend it up like a door to get you close. I did this on both sides, got a 1/4" threaded rod with a small wire brush on it and was able to get off the surface rust, cleaned it up, coated with rust encapsolator, seam sealed, applied undercoating with a gun with long nozzle, then for good measure glued in the plastic hats. Then welded my "door" back in and opened up the drain to lessen the chances of crap getting stuck in there.


If you open it up like this you will know the exact condition of what you got.
 

·
Registered
Joined
·
214 Posts
I too found a pretty good collection of pine needles and leaf debris in there. I was able to get mine cleaned out without surgery.

There's a rubber plug in a round hole; that provides an extra path into the area in addition to the drain opening. I was able to poke in there with a dowel and various other implements to loosen the material, and vacuum it out. A few shots of compressed air along the way helped also. When I was done, I found sound metal with light surface rust -- certainly sound enough to not need to replace anything. My plan is to clean it all up as much as humanly possible, maybe even resorting to a little sand blasting if I can get in there. I have this little sandblast rig... it's just a sandblast gun with a siphon hose and pickup tube, you stick it in a bag or bucket of media and have at it. It's not good for much, but it will be plenty for this little area. Then coat with POR15 or similar product to stop the rust, then brush on seam sealer around the base of the hats.

Like I said, I got lucky -- there are no rust holes at all that I can find. The metal on the hats isn't even noticeably thin or badly pitted. If ONLY the quarter panels were in that condition!!
 

·
Registered
Joined
·
2,987 Posts
IMO, if you're car will be a DD and driven in the rain, bite the bullet: remove the cowl top so you have full access to weld in metal as needed, seal and paint. I welded my cowl hats 100% so I'm not just relying on seam sealer to stay leaf free. You may also uncover rust at in the cowl sides/weld flanges like mine had.
 

·
rdnck1
Joined
·
209 Posts
I had the same issue. Leak was extremely small but it was there. To get the crude out I used air then shined a light through the top vents and could see it shining through a couple places. See pic where the rust through was actually in the upper right hand side of the cowl. The seam sealant was also not great in several places and would be damp below when a water hose was used to check the cowl. I went ahead and replaced the whole cowl assembly not knowing how extensive the damage was. In hindsight, a partial replacement would have worked just as well if not better and had been easier. The old cowl wasn't as bad as I originally thought but now I'll be good for another 50 years. Good luck, Jim
 

Attachments

·
Registered
Joined
·
448 Posts
Most will say to replace the whole thing and epoxy prime the inside of the new one...


Has anyone tried having a new lower cowl galvanized? That would be the way to go if you could find a shop that hot dips and it doesn't warp the panel during the process. The Dynacorn stuff is coated in a cold galvanizing that they call a weld through primer.
 

·
Registered
Joined
·
4,374 Posts
I think the cowl itself was one of the heavier galvanized pieces originally.
I was able to wiggle the stove pipes off of their spot welds and remove them. They are a lot thinner than the cowl itself and should come out without harming the surrounding metal. I also have hands larger than the President so those couple of inches gone will let you get your hand or a hose up in there easier to remove that mulch turned dirt. i think its only 3-4 bolts to remove the splash shield from behind the tire and you will see the corner cowl drain to make sure thats clear and also to not just push the crud from the cowl onto the back side of the fender.

Vacuum, leaf blower, air hoses and patients will get it good and clean. Then treat and coat to your delight.
 

·
Registered
Joined
·
1,755 Posts
If you can see rust and its leaking - just replace the lower. My upper ('66) was perfect, so my body guy just replaced the bottom. I had him prime and finish paint ALL inner surfaces of the cowl. That is not per the factory - but I don't want to ever have to deal with the cowl again - besides, who would want to see a '66 HiPo/automatic special ordered anyway? j/k, I used to show it sometimes in the '80's, but the snobbery was too much for me so I stayed on the 1/4 mile and SCCA tracks instead.
 

·
Registered
Joined
·
1,889 Posts
I'd do at least the bottom... I'd do the top as well because it doesn't cost much more than doing only the bottom, and it can be done using the original "spot weld" method. If you replace the bottom only, you'll be filling the holes you drilled in the top rather than a true spot weld. The cowl is structural. Do it once, do it right.
I didn't have the option of "either/or" on my 69. There's no patch kit available and the only cowl replacement was top and bottom, and I'm glad it was the only option.
I welded the bottom in, primed it and painted it, but masked off the lip so I'd get a clean weld when I did the top. Granted, Ford didn't paint the lower cowl, but you can't see it once the top is on.
Heck, you've got it apart anyway, and Dynacorn does a really nice job with the repro parts. Might as well do the whole thing.
 

Attachments

·
Registered
Joined
·
1,542 Posts
@wicked93gs If you are concerned about TIG torch clearance check out a flooding cup. It's all I use now. You can go with extreme stick out, minimum 3/4" and more. If you use that cup with good stick out on a 9 or 20 torch with the smallest back cap it shouldn't be an issue.

https://www.arc-zone.com/monster-nozzle-a-mn12-2
 

·
Registered
Joined
·
4,717 Posts
I’m with Frankie. On my 66 I replaced both top and bottom because they needed it. The replacement fit well and made it easer than repairing the old one.

On the 65 Fastback I am working on, I just opened the cowl and found the bottom trashed even though it looked good from underneath. I sand blasted the cowl top and will reuse it to preserve as much original metal, as possible. It was in very good shape. The bottom had to be replaced. When ordering just the bottom, what they sell for 65/66 is really a 67 bottom. It works but will take some trimming and fitting. Not quite as easy as the two piece unit, but saved about $225 by saving the original top.
 

·
Registered
Joined
·
674 Posts
If you clean out the debris and it still leaks there is only one thing to do. Crack it open!
If you are dealing with a '67 or '68 don't chose the small repair patches. They are made for '65/ '66 and will need modified heavily to fit the driver side. (guess which repair patches I used? lol)
If the full lower cowl was available I would have definitely gone that route. If you replace just the lower remember to make sure the holes for the wiper arms line up with the upper before you finalize your welds. I almost got caught on that one.
 

·
Registered
Joined
·
1,178 Posts
Discussion Starter #19
Well, I was able to snake a shop vac hose in one cowl hood, all the way across the cowl to the other cowl hood, the reach up in there and break up the 50 years of mulch and vacuum most of it away(good thing it was a 6HP vac). I still cant see the cowl floor of course...but it feels badly pitted. So if its not leaking now, it will be soon. I was going to kick this can down the road, but that changed my mind...so I am ordering a new lower cowl at the least(more likely both lower and upper because I can use a spare upper to play around with methods for making a removable grill that could be interchanged with a blank panel depending on weather and for cleaning the cowl)
 

·
Registered
Joined
·
1,889 Posts
I can use a spare upper to play around with methods for making a removable grill that could be interchanged with a blank panel depending on weather and for cleaning the cowl)
… uhhh, the grill is a separate panel that goes over the cowl... at least it is on a 69. Pretty sure it's the same on other years as well.
 
1 - 20 of 46 Posts
Top