Rain Gutter Puddy

Anybody know what the puddy/caulking is that is cracking and falling out of my gutters?? Is it like a common body seam sealer?  It's hard and comes out in chunks. I would like to grind it all out and replace it before my van hits the paint booth. Thanks.

Found this thread:

https://vintage-vans.forumotion.com/t12545-rain-gutter-seal?highlight=gutter

That stuff is a factory seam sealer that they put in the gutter, set the roof skin in it. then spot-weld through it and fillet the leftover smooth......It spends years in a very elastic state, until it dries and cracks.... nothing sticks to it and it's elasticity returns when you try to either grind or scrape it.... Often, when it starts to deteriorate, water can get under the edge of the roof skin as it puddles in the gutter.....
My suggestion is to find a product you like that sticks.... and to fill the gutters up to the top so that they no longer contain standing water......I did this about five years ago above the windshield of my 68 suburban using marine-tex epoxy... and still good!

They make a special seam sealer type product for gutters, it's self leveling

Thanks guys. I'll get out there and see what I can find.

Yes, I agree, I would say its seam sealer, NAPA sells a nice version in standard caulk tubes, its pretty thick but will level out before it sets.  I used it for touching up the gutters and also filling small rust outs in the inside post corners, fender wells, holes in the floor from PO's, etc.  Works well with small patches of sheet metal were you don't need structural integrity, just to fill holes.

Should I remove the original seam sealer in my rain gutters or just make sure its all dry and lay a new coat over the old?

Remove it if you can. Sand out the crusty stuff. I'd apply some form of rust killer before you seal it also. You can paint over seam sealer. Makes another layer of protection. Any exterior caulk is a maintenance thing but should last years. Just avoid silicone.

Yeah never use silicone for anything, car or home. It's the worst sealant. Unless it's silicone spray lube for carb, hoses ect.

Another thing is after you chip grind and sand all that out, remove ALL rust and then get a rattle can of that 2K epoxy primer with the activator button on the bottom and after sanding and removing all rust and cleaning it with wax remover, spray it with that. If you can, apply the gutter seam sealer within 24-48 hrs, the sooner the better after it's dry to the touch.