Inspired by other threads I purchased these from eBay thinking it would be an in an out job. I found the nuts to be completely disintegrated with no grip and bolts that snap off. Only a few nuts were in good shape.
Would a body shop be able to restore the bolts and install the boards? I also couldn't figure out the use for the included brackets.

 

Wow! Unfortunate you have this problem! You must be in an area with salty roads (?)

I've never inspected those bolts on our GLK, but the last time I was under the GLK (doing other work), all other types of bolts were fine. Out of curiosity, later today I might take a peak at our running board nuts and bolts.

And yes, I'd take it to a body shop for evaluation and a quote. As far as the parts that are packaged with the running boards ... isn't there an Installation Manual included?? One would hope so.

 

I would leave the old bolts alone , maybe paint them to slow rust. I would just screw the running boards on and be done with it. You could spend a lot of money for the same end result. It’s not worth it. If you choose to just screw it on find the location of brake and fuel lines first . Often they are in the rocker panel.

 

Well, okay, I didn't do it yesterday. But during a commercial break during the NHRA drag races just now (Ms. Force lost out ), checked. Funny cars are up now.

Anyway, I just layed down under our 2014 GLK ... I checked all the stock bolts and nuts holding on the running boards ... absolutely zero rust or any sign it will ever happen. Admittedly, we are in south central Texas with a 10 month summer and zero salt on roads (except of course, in the kitchen).

 

Nice! Everything goes to **** around north east, I want to keep GLK forever, so expecting to do a lot of body work.
The boards came without the manual, so lots of guide hunting online to no avail.

 

Cut the nuts off if aero-kroil or PB blaster won't free them.

 

If you cut them off how can you get new bolts in? They look like large like structure bolts to hold everything together.

 

Just cut the nut... Otherwise I would have said "cut the bolts off", but that would be stupid; it's a lot easier to just snap them...



Note to self: Never ask Mmr1 to cut off my ankle bracelet!

 

The threads are junk, you will be lucky to get a new nut tight, and what if the bolt spins? You can’t hold it. . Why not just screw it on, bypass the old nuts, you’re not going to stand on it! It’s for looks. Your way is a days job that might not work.

 

Looks like typical automotive clip-in fasteners.

Pry/tap the rusty studs out of the slot in the body in white. Install new OEM studs or use an appropriately sized standard bolt with washer. You will need to engineer an anti-rotation feature in the bolt if you can’t source OEM studs with integral square anti-rotation plate.

Install new nuts in the new running boards similarly with OEM nuts and square anti-rotation washer or use a standard nut with washer.

Hindsight being 20/20 as it always is, this job would have been best not attempted.