I am currently doing frame off restoration of my 77 F150 and during this process I removed a lot of what looked like some kind of body caulking or putty that was used to fill the large holes where body panels met where seam sealer would not work. The only thing I've been able to find at the store where I buy my paint is 3M Strip Caulk. This strip caulk is black and is packaged as a box of 60 1/8" x 1' strips. The material I removed was white and reminded me of Window-Glazing putty. What are you guys using to replace this old body caulk?

 

Depends as to where it's at. My 68 had the stuff you are refering to, I think it's body filler. Most of mine had cracked and started coming loose. This did not happen to all joints, just the ones that may have been flexing. Which may have been one of my cab leaks by the windshield. Since I do not want the paint to crack, I'm filling the gap between the 2 sheets with welding rod, and welding it solid. This way the joint will not flex, and prevents leaks. Then fill the gap with body filler of your choice.

I would do what you think will hold up the best. Since my 68 cab was assembled with over lapping panels, aligned and spot welded in place. The gaps were used for adjusting fit. I have some of the joints by the windshield that you could slip a 3/32" rod in. These are the reason I'm placing a welding rod in the gap to help fill the hole. Being welded will stiffen it up, so it want crack out as before.

The POR crack and putty seam filler, may be a good choice, too.

 

The areas I found the caulk in were on the underside of the cab near the cab corners and on the underside of the cowl vent area near the where the front fenders bolt up. The holes are large enough to put a finger in and they all seam to be in places where three body panels meet at a corner. I will try and get some pictures of the areas I pulled the caulk out of, so you have a better idea of what I'm talking about. I used Eastwood's Seam Sealer to seal the spotwelded panel seams, but some of the holes are just too large for the brushable seam sealer. Thanks.

 

Maybe you can use a snap-in hole plug. If you are keeping every thing as factory restoration, you need to use the same stuff as factory. Maybe Mil1 or NumberDummy has a part listing for this filler.

 

I noticed the same globs of stuff on my cab, mine are all cracked leading me to believe it's not a seam sealer but rather some type of putty. I didn't check to see if it would flex, i just thought it was putty.


Maybe you should just fiberglass it and forget it. While you got the cab in the shape it's in and easy to get to.

 

Mine is hard as a brick, so it's not the seam sealer I'm a custom to. I think its a body putty. I have areas that were painted and not prior to the putty. In most cases it just chips out in pieces. Not bonding to bare metal or painted surfaces.

 

cujo8, i found the same stuff in the corners of my '78 crewcab. It does remind me of window putty too. I'm also needing to replace mine because I had to remove some of it to replace body panels and other metal pieces. Can anybody help us out? Mine was still kinda plyable, not hard and brittle like was mentioned earlier.

 

The 3M joint sealer in caulk form is a light white to light gray in color. Remember my 68 is almost 40 years old, so a lot of things can change from due to age. In most cases plyable substances harden with time. The area you describe is area joint sealer are used.

I found mine on panels that were spot welded in place. Which is most joints on my truck. Including where the back of the cab meets the door jam, a long seams. 3 joints on the inside along the doors and windshields (x2). It was also used along the floor pan and kick panels. The brushable joint sealer used where the cowl and firewall meet. And below the rear (cab) gas tank on floor.

Can you tell if it was applied before paint? All of mine seam to be before paint.

 

the stuff is called PLASTISOL
I used to work at the GM Assembly plant at Lordstown years ago...it came out of guns that kind of looked like grease guns and was pink in color when applied - it dried to a white/white grey....they applied it to seams and welded flanges to seal up the chevy van bodies

I dont know if its avail to the aftermarket - been years since I even thought about it and am surprised I remembered the name...

 

All the sem sealer was applied before the truck was painted, but the material I'm talking about was used to fill larger holes and was applied after Paint. It was whitish gray and was not completely hard but very stiff. It didn't seem to be bonded to the surface very well, but I had to pry out because it was a tight fit in the hole it was filling. The material pretty much came out in one piece and not much if any was left sticking to the metal. Like I said earlier it reminded me of aged window glazing putty and I'm thinking that using window glazing putty might not be a bad idea.

 

Mine has a lot of snap in plastic plugs used to fill big holes. The ones where wire passed through used rubber in some case if going into the engine department. Yours being newer Ford may have got away from the plugs to save $0.05 . Can you post a picture so I can see what/where yours is and looks like. I know there are some diff between 77 and a 68.

 

I also have the plastic hole plugs on my truck, but the body putty was used to fill irregular shaped openings like:

 

My 68 does not have any holes like that. As far as a putty to use, if it does not fully harden, there is some refrigerant sealer like that. Its used to fill air gaps around lines. It's pretty cheap if I recall. I was looking for my box several months a go and did not find it. It comes in a rope form, not like plumbers putty or glazing compound.

 

I have a can of brushable seam sealer. This is used for wide joints and sets pretty quick. It has the window putty appearance. I found a putty knife works well as a 1-2" wide brush. Once you open the can you must use it all. It reacts with something in the air, O2 or H2O. I purged the can with nitrogen, don't know if it will keep, but it's an attempt to save 1/2 a can.