69 Stang Cowl Clean Up

[Machspeed 219]

Was inspecting the cowl on my project last night and it appears to be okay. There is, however, a lot of superficial rust in there and I probably should check it for leaks. From what I gather, I should poor about a gallon of water in the center of the cowl and see if it leaks onto the floor board, correct?

Lastly,  how would you address the superficial rust within the cowl? 

[Brian Conway 264]

I would not pour a gallon of water in there.  Sort of like shooting your self in the foot to see if it hurts ?

[Machspeed 219]

I know 

1 minute ago, Brian Conway said:

I would not pour a gallon of water in there.  Sort of like shooting your self in the foot to see if it hurts ?

I know what you mean but understand my car is completely apart, on a rotisserie, and fixing to go to the media blaster. If the cowl leaks, now is the time to find it and I don't know of any other way.  

[aslanefe 333]

6 hours ago, Machspeed said:

Was inspecting the cowl on my project last night and it appears to be okay. There is, however, a lot of superficial rust in there and I probably should check it for leaks. From what I gather, I should poor about a gallon of water in the center of the cowl and see if it leaks onto the floor board, correct?

Lastly,  how would you address the superficial rust within the cowl? 

I would use a wire brush to clean first, as far as I can reach from the opening on top and from the heater hole. Then treat it with ospho or other rust convertor. Run water from a hose to check for leak. If no leaks, brush some epoxy, then spray rubberized coating. They have some cans that come with a piece of hose and a nozzle at the end that sprays out radially, that should get the rubberized coating to hard to reach areas.

[Casgar 21]

18 hours ago, aslanefe said:

I would use a wire brush to clean first, as far as I can reach from the opening on top and from the heater hole. Then treat it with ospho or other rust convertor. Run water from a hose to check for leak. If no leaks, brush some epoxy, then spray rubberized coating. They have some cans that come with a piece of hose and a nozzle at the end that sprays out radially, that should get the rubberized coating to hard to reach areas.

Can you really reach far enough just from the center openings? I would imagine you would have to cut off the ends to reach behind the vent intakes, which from what I understand is where most of the rot usually is. This is what I'm thinking of at the moment. That, or remove the whole top part of the cowl. I'm more or less at the same stage as Machspeed, so it's now or never.

[newstang 388]

There will be no getting around it, you'll probably need to replace the cowl.  Media blast it and you'll see a constellation when you put a light to it.

[aslanefe 333]

6 hours ago, Casgar said:

Can you really reach far enough just from the center openings? I would imagine you would have to cut off the ends to reach behind the vent intakes, which from what I understand is where most of the rot usually is. This is what I'm thinking of at the moment. That, or remove the whole top part of the cowl. I'm more or less at the same stage as Machspeed, so it's now or never.

If you get some wire brushes that are metal (usually used to clean welds) you can bend them and reach around the hat to clean and knock of most of the rust. You can also weld a piece of rod to them and make the handle longer. With a longer handle, you can bend the brush to a U shape and go in from inside the car (through the hat) to reach outboard edges. I use my boroscope (and mirror sometimes) to see which areas I cleaned, which areas need more brushing.. I even MIG welded a patch in that area through the top opening with the help of a mirror. When the engine is out, get inside the engine compartment for better access through top. Drivers side is easy, there is no hat in there on 69 and 70s so you can reach all the way with a straight brush when you remove the wiper motor. Your suggestion is also an option, but the damage in your pictures can be seen from the top opening and from inside with the help of a mirror, so cutting it open just to see if there is damage is unnecessary (at least for me). You can get creative with a paint brush and modify it to apply your ospho to treat the rust and apply epoxy. To fix the damage that are seen on your pictures of an earlier car (looks like a 66 I fixed by opening the ends), I have done that couple times and on an other case I cut a section from the top of the panel about 2 inches forward of the windshield and around instead of remowing the windshield, drilling out the spot welds and removing the top part of the cowl ( then welded it back after repair) but that car had a lot of damage on both sides.