I was trying to prep my del Sol's engine bay for repaint and engine swap. Well, most of my bolts and nuts were corroded (rusty) so I tried to remove various nuts and bolts for replacement.

Anyway, I was trying to remove the nut on the (brake) proportioning valve and SNAP, there's my nut (now essentially a bolt) with most of the 8mm threaded piece seized right in. I'm not sure if it's actually a stud because I don't think it unthreads from the other end. It looks like it's welded in there? I haven't removed my dash yet so I don't know what it looks like on the other side of the firewall.

Maybe I should have taken a die to the threads before attempting this but hindsight is 20/20. The threads were so corroded. The metal seemed kinda weak too.

What is the typical way to fix this? Weld something in its place like a bolt with most/all of it's head cut off? I can't weld... Replace the firewall? Probably too expensive for me but that'll clean up all the rust there... Drill out the threads and use a bolt on the opposite side? I'd have to have someone hold that steady while tightening the nut though... Or is there like a plate with threads on it that you slide in from the dash side? If so, part #?

 

You can probably go with out it bolted to the firewall, it should stay in place with the lines holding it.

 

Yeah, it will just stay there but the reason I'm in this forum is to repair it. I want to bring the car back to as close to new condition is possible as cheap as possible. If I could afford it, I'd buy a rust-free Del Sol from a hot/dry area.

 

just drill it out, slide a bolt through, and tack the head of the bolt from inside.

 

Good luck with the heater core. Cut it off flush, tap a hole right through the middle of the broken stud, and use the next smallest thread pitch bolt or stud. Try a 6mm diam. You don't need it to be super strong since there is no load on the junction.