Need some advice from you metal fab/welding/bodywork guys

[CubbyChowder]

Hey guys, I just need some quick advice here. I just got done welding in a fender flare on '73 BMW 2002, and I ground everything down so it's flush with the body but there are little cracks between the welds here and there and little gaps and what not. Here are some pics to describe:





I want to smooth everything out with a little bit of filler to make it look good now. Is it safe to apply body filler over this area into the cracks or do I need to make sure that everything is covered in metal? In the pictures, it kind of looks like the welds don't penetrate the new fender flare very well, but let me assure you that it does. They are honestly pretty little cracks, and I can't see it being too huge of a risk, just need some input from someone who is a little more experienced than I am. Thanks in advance.

[nellydragracer]

You need to make sure that every single crack/gap/pin hole is sealed or else when you fill it, after a while moisture will get in and ruin all your hard work.

[CubbyChowder]

You need to make sure that every single crack/gap/pin hole is sealed or else when you fill it, after a while moisture will get in and ruin all your hard work.

that's what I was thinking. Do I seal it will body filler or should I do it with something else? It shouldn't be hard to fill the gaps in, I just want to do it right.

[nellydragracer]

Body filler won't seal it, by its nature body filler absorbs moisture. You can either seal it from the underside with a decent seam sealer or get a bright light shine on the underside and weld up any holes, but you should still a bit of seam sealer underneath to be safe.

[CubbyChowder]

Body filler won't seal it, by its nature body filler absorbs moisture. You can either seal it from the underside with a decent seam sealer or get a bright light shine on the underside and weld up any holes, but you should still a bit of seam sealer underneath to be safe.

thanks for your input

[benz88]

Filler over that is fine. But seamseal under it if you can

[CubbyChowder]

Filler over that is fine. But seamseal under it if you can

yeah I still need to weld the wheel well back to the fender, and once I do that, I will go over everything underneath with seam sealer.

[andybob]

I'd run another bead with the welder to fill the voids, then go to town shaping with a grinder. That way you use as little body filler as possible so there is less of a chance it will crack.

[Khalil]

I'd run another bead with the welder to fill the voids, then go to town shaping with a grinder. That way you use as little body filler as possible so there is less of a chance it will crack.

This. It'll be a lot stronger.

[renngolf]

Looks like some lack of fusion along the toe in some spots. At this point its up to you, you can either run a bead of weld across it, or if you think its welded enough seal all exposed metal with epoxy primer, then do the initial fill with fiberglass reinforced filler, then followed with some light weight filler/glaze.

[CubbyChowder]

I'm going to weld up all of the gaps and grind it back down so there are minimal cracks/gaps. All of the gaps you see on the bottom of the weld, which meets with the top of the new fender actually just need to be ground down more as they penetrate the fender a bit farther in, kind of hard to explain.

[oHSo EuRo]

Run a bead weld to fill as much of those cracks as possible and use a sealer on the underside. That would be the best way to do it. The less filler the better.

[CubbyChowder]

I agree the less filler the better, and that is my plan. Unfortunately, this whole quarter panel is dented up pretty badly and will require more filler than the other three corners. I have a quart of brushable seam sealer coming in the mail which I will use all over the underside to block out water and moisture.

[oHSo EuRo]

Use a hammer and dolly if you can get to those dents and pop them out as much as possible. If they are big enough find a Uni Spotter to pop em out. Zic on the forum did an awesome job with his fenders by sealing them. If you got some questions shoot him a PM. He's a good guy, he won't mind giving you some advice I'm sure.