!971 GMC inner fender sealing

[prateroad]

I'm onto another truck today. I've never pulled the inner fenders off a fleetside but bought a bed without them. What does everyone use for a sealer between the inner fenders and the bed? I have both brush on and a caulk tube of 3M seam sealer. I have used the caulk 3M on the seam at the back of the cab on top but it seemed to crack. I don't know what the factory used there but I don't want any cracking. This is a nice bed.

[sick472]

Right Wrong of Indifferent...I always use rope caulk for sealing between bolted body panels. I put enough in so that it squishes out on both sides and then just booger roll off the excess. I have found it in cars where it would have come from the factory and it's still pliable and easily scraped off with a plastic scrapper after 40 plus years. It's usually found in the window repair/parts isle in the hardware stores.

Edit: if your talking about the exposed visible joint between the bed fender and bed wall....I leave it without any caulk. That seam sealer cracks on me every time and I would just do without it where visible.

[prateroad]

Is that the 3M black strip caulk some call dum-dum? It has strips of paper between them to keep them from sticking together. I thought about using that on the visible bed to liner part to keep dirt out of the seam. Correction, I think the dum-dum is the a/c foamy black stuff.

[sick472]

The rope caulk I have always found in the hardware stores has been whitish and was not 3M brands. It is a gummy substance, kinda like a cross between Play-Dough and clay. I would not use it any where that it is visible and can be touched as it does not set up and harden. It stays clay like forever. If I was running a bead around the interior of a painted bed...I would use a polyurethane tube caulk. I have used it on a vinyl top drip rail and consider it the best caulk for this type of application. It is really messy and you need to take proper precautions so that it does not get out of control and goober all over the place. It cleans up pretty well with mineral spirits if done at the moment of the mistake. Beware: my finger tips were blackish for a week after sealing that drip rail, but I was smoothing the beads down so they were more like a gutter in the driprail than a upward hump (dip finger in mineral spirits, smooth a few inches, wipe finger, & repeat).

[57taskforce]

It’s also called butyl tape. I used it to seal up my high hump cover.

https://www.acehardware.com/departme...B&gclsrc=aw.ds

[72c20customcamper]

I use the 3m Butyl tape .