I am not sure what is the best way to describe it, so here is a picture:

Striped metal surface

Striped metal surface zoomed out

For comparison, the metal on the other side is smoother:

Other side of engine bay

1 Answer 1


That’s not a weld bead. What you are looking at is body sealer. Typically that is applied by a robot in a weld seam, before the panels are positioned for welding. The vehicle panels are joined with spot welds. And when the vehicle is sent thru the paint ovens, that sealer expands and hardens up.

enter image description here

And after staring at this photo for a while it looks like this manufacturer does a post spot weld top apply. The results are essentially the same. The soft sealer hardens up in the paint oven.

And in that state you have a well built, waterproof sealed area. Note, there is a ton of water thrown up into the fender area when ever your vehicle is driven in a rain storm.

Those wavy lines indicate a bit of jitter from the original application robot. Nothing to worry about.

  • Are you sure? I looked at images of weld beads and body sealers, and it seems to be the former. Body sealer seems to be white in color, and the one in my image is actual metal.
    – hb20007
    Aug 24, 2021 at 10:44
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    Look closely at your photos. The bodies are welded together with spot welds. A spot weld is visible as a round “depression” dot approximately 3/8” in diameter. Your top photo has three spot welds, just below the sealer. Virtually all vehicles are manufactured this way. Note, at the plants I worked at there are MIG machines available at key points in the body shop. They are used by hand to perform repairs. I will say those MIG guns were used very infrequently. Maybe once or twice in 500 vehicles built.
    – zipzit
    Aug 24, 2021 at 14:48
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    I wanted to respond to your comments about color. Body sealer is applied before paint top coat. The sealer is also hardened in the paint cure ovens. Note, if you wanted to confirm you could take a sharp utility knife, and slice a sliver out of that bead. You would be able to see the original sealer color beneath paint.
    – zipzit
    Aug 24, 2021 at 16:26
  • Yes the bodies are all spot welds as that is the cheapest process. Possibly some MIG welds in frame members where the owner never sees them. Aug 24, 2021 at 19:02

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