Drilling small holes in roof

[Brunc]

I am thinking about drilling small holes in the top or bottom of the roof to squirt ospho in to the cavity.

Is that a dumb idea. I would ultimately fill the holes.

My thought is it would flow into the crimps around the windshield and other mock and crannies.

 

[PrairieDrifter]

I would buy a cavity wand kit and go through the windshield visor holes and dome light hole. If no dome light, there's a pocket in the cab corners that goes into the roof cavity.

You'd have to drill decently sized holes to do anything productive without some kind of wand.

 

[Grit dog]

^What he said. Although them spray cans of rust reformer paint like Eastwood are not cheap.
I’d look at it like this. If you have rust problems in an areas, definitely do those areas. In my case the otherwise 100% rust free 86 had some fairly serious rust thru around the windshield frame/A pillars. I had to cut and patch. So I used the holes that were there (from rust) and sprayed everything around the windshield before patching and welding up.
I don’t think you’ll be able to get any reasonably good coverage without a wand that sprays in all directions.

 

[Brunc]

I would buy a cavity wand kit and go through the windshield visor holes and dome light hole. If no dome light, there's a pocket in the cab corners that goes into the roof cavity.

You'd have to drill decently sized holes to do anything productive without some kind of wand.

Excellent. I don’t see rust but just want to be extra cautious. Great advice!

Thank you!

 

[Grit dog]

Excellent. I don’t see rust but just want to be extra cautious. Great advice!

Thank you!

If you’re still working with the cab with the rusted jambs I can see your concern. If you got a clean cab then if it ain’t rusted on 40-50 years and the common rust areas (lower cab) are clean then you have nothing to worry about.
I did mine out of abundance of caution even after I concluded that it rusted from the outside-in around the windshield and back window.
Mine was an odd case though as I’ve seen plenty of rust bucket squares that didn’t have the rust thru like mine, which again, had zero rust elsewhere. The frame even barely had surface rust.

 

[Brunc]

If you’re still working with the cab with the rusted jambs I can see your concern. If you got a clean cab then if it ain’t rusted on 40-50 years and the common rust areas (lower cab) are clean then you have nothing to worry about.
I did mine out of abundance of caution even after I concluded that it rusted from the outside-in around the windshield and back window.
Mine was an odd case though as I’ve seen plenty of rust bucket squares that didn’t have the rust thru like mine, which again, had zero rust elsewhere. The frame even barely had surface rust.

I have since ground down both passed her and driver’s jambs to bare metal. The rust was due to the seam sealer, breaking down. So I plan to repair the spots that need repair. The windshield seams had very minor rust. So over all the cab actually looks pretty good. I did go the route for a while to find a cab, but as I worked in this one, I realized that it was repairable. But as I was working on it, I thought why not try to add some protection from the inside.