Rear License Plate attachment nut gone?

Long story ... ahhh.

I needed to change the license plates on the 2010 Prius and right rear license plate bolts wouldn't come lose. With a couple of twists the aluminum (why does Toyota use aluminum Philips screws???) screw head was toast.

So I gave it some WD40 and waited 20 min. Then took the vice grips to the bolt since the Philips screw driver wouldn't turn. I hear a "clunk" (sound like when you get a stuck bolt loose) and the bolt came out. Yup! Just dropped out.

The left attachment nut looks like a regular 6M bolt attached somehow to the back door. The right attachment nut is gone. There is now nothing to which the replacement screw can screw into. (lots of swearing and loud yelling ensued.)

I presume whatever was on the inside of the back door came loose and will rattle around but am not sure how to go about figuring out where this bolt thing went.

The repair manuals haven't been helpful since they don't talk about attaching the license plate. (Or perhaps I haven't found that section of the 7k pages yet.)

So presently the license is hanging by one bolt.

?Help?

Thanks in advance.

 

Thanks for everyone's comments.

Sorry for the delay. It was raining cats & dogs so didn't want to get soaked while checking it out in the daylight.

Here are the pictures showing location. Apologies. I should have posted those yesterday.

Today when I needed to go out, I heard the nut or whatever was attached to the back door roll around. Turn right and roll ... roll ... roll. Turn left and roll .... Oh this will drive me nuts. (pun intended )

Any recommendations on how to extricate that nut from the back door?

@bisco I don't think it is sheet metal. I feels more like the plastic similar to the bumper. The hole looks to be the same size as the one with the attachment nut.

@David Beale Great idea. I'll have to go and see what those look like. I remember in the old days there were nylon inserts for license plate attachment. I wonder if those are available somewhere? After a quick look Amazon has lots. "Nylon License Plate Nut" or "Clip".

@Mendel Leisk Also a great idea. Nylon bolts should alleviate the problem with aluminum bolts oxidizing and getting all seezed up.

Off to the store.
Cheers!

 

@Mendel Leisk Where would I get access? Could I get access through the license plate light door?

 

Thanks for everyones help and suggestions! The saga continues.

I removed the interior panel. Had to visit 3 stores before I found one that carried interior panel removal tools/nylon tools. The removal wasn't as hard as I thought. But, I'm now worried about the reassembly ... not sure how to get this panel to reattach. Would probably make an funny video.

I found the nut that was rolling around in the tail gate. (See attached photo) It looks rusted. If the tailgate/back door is aluminum and this nut is supposed to be similar metal then how come there is rust? Aluminum oxidizes by creating a thin layer, usually white, that in the end stops the rest of the oxidization and protects the metal from further oxidation. The rust in the nut is definitely red. So this nut must be some sort of steel/iron. If that is the case, then how do they weld a steel nut onto aluminum? I didn't think that was possible. I don't suppose the nut and bolt were steel???

When I look at the nut is almost looks like it was glued/epoxied??? Is that possible? Would it hold?

I've bought some stainless hex head bolts (M6 x 1 x 20 A2), M6 stainless A2 nuts and M6 washers. I won't put any more Philip's pan head screws onto the license.

I will need to seal the hole when I install the new bolts & nuts so moisture doesn't get into the tailgate/back door. This nut can't be welded back on without significant difficulties. In addition to the dissimilar metals issue, the place where it's supposed to be attached is underneath a metal cover with about 1/2 to 3/4 inch clearance. You can't remove the cover as it's also welded down. (But that looks like Al & Al). So maybe I'll try epoxy?? Dumb idea??

Thanks again!

 

I don't think the rust was the problem. I suspect it was more about a bad weld.

I appreciate everyone's advice. Just to finish and close this thread, I thought I should add what I did to fix the problem.

Here is a picture of the license plate nut.

I purchased the two part epoxy. (Permatex Steel Weld 2 part epoxy). Put a bunch on the nut and around the hole. Then put a bunch of the epoxy around the nut when attached. You really have to be careful that you don't get any epoxy on the threaded portions.

It was a real PITA to keep the nut in the right location. So I used a screw and a bunch of flat washers to attach the nut. Once the epoxy was sticking in place, I removed the screw and washers.

The following picture shows the "repair". So far it's held.

Thanks again for your help.