rust inside unibody?

[lespaul]

Ok. I have my 73.5 T up on jackstands/ramps and have hand scraped off about 80 lbs (no lie!) of oily dirt and crud from underneath and in the wheel wells. What remains is the original undercoating and a very few patches (2" x 2") of surface rust where the undercoating has worn off or I scraped it off. In one location where the rear seat well is located, I found a "crunchy" rust spot that went through the body (about a 4" x 4" spot until hard metal is found on the edges).

The scraping also revealed a line of very small 1/8" holes drilled right down the center line of the body at about 1' intervals and a few in other locations. Some had rubber plugs in them. Are these original or did the PO have some sort of anti- rust treatment performed? How do I know whether or not water has gotten up inside the unibody through these holes and is causing unseen rust? Should I squirt oil up in there?

My basic 3 year plan is to first carefully inspect all the undercoating and where ever I have any suspicion, remove it only in that location (I have seen the threads about how to do this), then POR, then paint, then replacement undercoat that spot. JThen the trunk, then the engine compartment. Once this is finished (by the end of this winter), I will drive the car for the summer and fall (runs great!) and then tackle the exterior paint job next winter and the interior the following winter.

Any comments, suggestions, revisions, warnings? Does this make sense? My objective is to drive this car, enjoy it and keep it as original as possible. I have no present desire to show the car or race it.

[randywebb]

good plan

take off the fenders and check at the A pillar also

no idea re the holes on the centerline - the factory did have drain holes for its various dipping processes...

[lespaul]

Thanks for the input Randy. I appreciate it. I want to do it once and do it right.

I know what a fender is - smile - (and will take it off), but what and where is the A pillar?

[randywebb]

it is the frontmost pillar and the top forms the windshield support that attaches to the roof -- my '73 had rust there once it was all stripped - only place on the car with rust

[ossiblue]

lespaul,

The holes in the underbody centerline are factory, they should have plugs in them. There are a few others too, I think beneath the rocker area. No telling how long they have been missing, nor how often, if ever, water may have entered. My guess, from experience with two 69 longhoods, is you're probably safe with the water entry issue, but I'd plug the holes now.

Your overall plan sounds good, but I offer a warning. The undercoating inspection is not going to be completely thorough. These cars tend to rust from the INSIDE, as evidenced by the seat bottom hole you found. I would suggest a close inspection of the floor, rear deck, rear seat wells, and pedal cluster areas from the inside. Yes, you'll have to deal with the sound deadening material, but visual and "ice pick" probes will accomplish alot. As I'm sure you're discovering, there are potential rust havens all over and under the pre-galvanized cars. Good luck and enjoy the ride.
Larry

[lespaul]

Got it. Thanks again. I will post some pics of the project as it now stands -- painted Ford Grey by PO. Yuk.

[lespaul]

Thanks Larry. I poked around quite a bit when I bought it and it looks pretty good so far. But, all the carpet and seats are coming out this winter for a thorough look inside too.

I am going to plug those holes right away.

I appreciate your time and advice.