Blind Weld

[FarFire70]

I'm an amatuer welder fixing some noticeable small (rust on the surface is 1/4"+") U-channel rust around the body mount bolt. Part of the U-Channel around the body mounts has rusted. It's a small section just above one of the body mounts. I am planning to remove and replacing that small (couple inches) section.

Question is how do I repair that rust issue and safely keep from the U-Channel rusting again?

My view is I can weld, prime, and paint the outside solutions, but I just introduced new raw metal in the U-Channel that I would not haven't covered...

I'm in the midst of a build for the long term and this un-exposed metal left in the repair leave me concerned I'm just setting up a future problem.

 

[JMT]

I'm an amatuer welder fixing some noticeable small (rust on the surface is 1/4"+") U-channel rust around the body mount bolt. Part of the U-Channel around the body mounts has rusted. It's a small section just above one of the body mounts. I am planning to remove and replacing that small (couple inches) section.

Question is how do I repair that rust issue and safely keep from the U-Channel rusting again?

My view is I can weld, prime, and paint the outside solutions, but I just introduced new raw metal in the U-Channel that I would not haven't covered...

I'm in the midst of a build for the long term and this un-exposed metal left in the repair leave me concerned I'm just setting up a future problem.

Can you use some weld-thru primer on the backside before welding?

U.S. Chemical & Plastics 1K SELF Etch Weld-Thru Primer (USC-3680001) https://www.amazon.com/dp/B00H2WEYYM/?tag=wranglerorg-20

 

[Mike_H]

weld thru primer, then spray some internal frame coat into the cavity after it’s repaired