2004 Expedition - help me identify this rusted box driver side rear corner

[whtbronco]

Seriously what is this box for in the driver side rear corner just below the tail light? I can't figure out what's in it. Can't get to it from the tail light recess. Ford generally doesn't produce something like this for nothing and it's not the same on the passenger side.

There is a formed sheet of like 1/8-3/16" black plastic visible in the hole and some expanding foam that appears to have been used as an adhesive for the plastic to metal.

While doing the fuel pump last weekend I realized this rust was back and worse. So I started investigating and found it was pretty rotten. I removed all I could tear off and drenched it with acid, let it dry and covered it with 2 layers of foil tape as a temp repair to hopefully keep water out.

I was planning to cut it out and replace it this coming weekend, but with 8-12" of snow now expected I'm not gonna want to be outside working on the truck. Not to mention this is the first real snow since my son started driving so it's time to teach him how to drive in snow. There's nothing quite like a RWD Ranger for learning to drive in the snow .

 

[Hamfisted]

Do you have any dealer installed options? Power running boards? Suspension ? Towing options ?
Pull the plastic box out and see what it is.


Expy Left Rear Corner Underside ....





.

 

[whtbronco]

Hmm, well that is certainly not what I expected to see, . I would agree that is likely from someone else's handy work, but I bought this thing with 13 miles on it and have more or less let no one touch it since. It's also spot welded and painted just like everything else under there. I dunno. Thanks for the reply though, at the very least I feel a little less foolish for not knowing what it is.

I guess I'll have to get my wife to take some more pics as I open it up and repair it to try and figure just what the heck it is.

 

[whtbronco]

Do you have any dealer installed options? Power running boards? Suspension ? Towing options ?
Pull the plastic box out and see what it is.

There were no dealer installed options, I don't think. I avoid dealer installed options, if it's not factory installed I'd rather install it myself. As soon as I have time to repair this I'll post some pics and description of what I find. It's certainly intriguing.

I feel like that orange expanding foam type material contributed to the rust.

 

[mehno]

I believe that is a storage box but it also contains a reset button. I was told when I bought my expedition that if you ever get rear-ended from behind and the car doesn't start then you need to hit that button to reset the fuel because there's some sort of switch that turns off the fuel tank I believe.

Seriously what is this box for in the driver side rear corner just below the tail light? I can't figure out what's in it. Can't get to it from the tail light recess. Ford generally doesn't produce something like this for nothing and it's not the same on the passenger side.

There is a formed sheet of like 1/8-3/16" black plastic visible in the hole and some expanding foam that appears to have been used as an adhesive for the plastic to metal.

While doing the fuel pump last weekend I realized this rust was back and worse. So I started investigating and found it was pretty rotten. I removed all I could tear off and drenched it with acid, let it dry and covered it with 2 layers of foil tape as a temp repair to hopefully keep water out.

I was planning to cut it out and replace it this coming weekend, but with 8-12" of snow now expected I'm not gonna want to be outside working on the truck. Not to mention this is the first real snow since my son started driving so it's time to teach him how to drive in snow. There's nothing quite like a RWD Ranger for learning to drive in the snow .

 

[mhg1]

Looks like a torque box.
Mike

 

[kep5niner]

I believe that is a storage box but it also contains a reset button. I was told when I bought my expedition that if you ever get rear-ended from behind and the car doesn't start then you need to hit that button to reset the fuel because there's some sort of switch that turns off the fuel tank I believe.

 

[whtbronco]

Well yeah the inertia fuel cut off and the air suspension switches are in that area. I am familiar with both, but they are above the floor pan, though directly over this thing. This box appears to be entirely under the floor pan and is not sealed so if it is associated with the switches I'd expect to have some dust in there. At some point over the next few weeks I'll cut it out and we'll know. I'm certainly looking forward to welding above me, yikes.

After studying the pic posted by Hamfisted mine looks the same, well except the hole rusted in it, haha.

 

[JamaicaJoe]

In the earlier generation, the evaporative canister is located in that corner. Are their hoses to the fuel tank and forward to engine?

 

[JamaicaJoe]

I almost bought a VW Jetta until I noticed someone had cut a rectangle from floor out of the trunk and then welded back in. Underneath it appeared there once had been a boxed in area. You have to wonder why.

 

[whtbronco]

In the earlier generation, the evaporative canister is located in that corner. Are their hoses to the fuel tank and forward to engine?

No the evap canister sits above the spare tire.

I don't think there's any hoses or wires coming out of it. We'll all know once I get some time to repair it.

 

[riphip]

I like that tape repair. I would have used the same for temp repair.

 

[whtbronco]

The tape you see doesn't stick real well. The first layer is just normal foil duct tape since it sticks good. I layered it so the seams were all down, but I still didn't like it. My neighbor gave me a 300' roll of the 7" wide foil tape you see and it sticks good enough to the duct tape and with no seams it worked well.

Usually I use a junkyard panel or buy a molded repair panel, this time I can use just a flat sheet. What I can't figure out is should I use just plain cold rolled 20ga steel sheet metal, aluminized or galvanized?

One of my co-workers suggested just using a plastic (HDPE) cutting board and panel bond to secure it. It's not a bad idea due to it's resistance to the barrage of road debris this area takes, but even if I did this I still want to replace the rusted sheet metal.

 

[twodollars]

I'd stay away from galvanized if your planning on welding.

 

[whtbronco]

I'd stay away from galvanized if your planning on welding.

Thanks, I bought some plain cold rolled sheet metal in 18ga.

 

[whtbronco]

I finally got back to this today. I have cut out all the rust, prep'd it to weld on the new sheet metal and got that mostly ready as well. I still have no dang clue what this box is for. It is not sealed which I basically knew before, but confirmed for certain today. It's just strange. I plan to complete this repair tomorrow.

I am confident that dang foam, rock hard foam, trapped enough moisture that it caused the rust. It was the adhesive that held the plastic inside.

There's a part at the top of the box inside that has identification molded into it.

L002G
MOLD #2
5L14-7841017-AD
116526
VEST GF24

Here's more pics.

 

[whtbronco]

Pics showing the inside. The file names are from my perspective looking towards the back of the truck. So Inside Left is actually the passenger side of the small box.

 

[whtbronco]

Couple more pics.

 

[whtbronco]

This is the same composite material the header panel is made from. It is quite strong and rigid. Though it's no match for an air hammer, LOL.

This is not quite the same part number, but only the last 2 characters are backwards and it is very similar to what I have if not the same. This pic appears to be the rear of the back of it. This same side can be seen from the front in the pic named "Rust cut out close up".
I guess it has been identified, all I can say is interesting and that damn foam adhesive that caused the front panel of sheet metal to rust out. This is the description I found:

Ford 5L1Z-7841017-DA Reinforcement - "D" Pillar

 

[whtbronco]

I was unable to get this wrapped up today so I taped it up again and put the truck back together so it's ready to haul me to work again tomorrow morning. Next weekend I'll try again, but getting the rust cutout and the replacement panel ready for install is more than half the battle.