Found rust below third row window and moisture under trunk carpet (1 Viewer)

[nodor]

Hello all. I am the new owner of a 1997 FZJ80. I decided to remove the third row seat belts because I have no plans to use the third row. Went to remove the right plastic panel in the trunk for the first time to remove the seat belt and found an area of rust just below the rear window. I lifted the window gasket covering the edge of sheet metal and there is a streak of rust that runs further along the entire bottom edge of the window. While doing this I noticed moisture underneath the carpet. The previous owner had the carpet replaced and covered the entire floor with dynamat. The bolts for the third row were removed and never replaced. The carpet was placed over these holes without filling them in with anything and thus left a hole communicating with the undercarriage. The carpet is lined with a thick rubber on the underside and no hole was cut out where the bolts go. Any moisture that made its way in-between the dynamat covered floor and carpet could not escape. There was enough moisture that one of the recessed areas in the trunk had standing water in it. I have no idea how long it has been like this. I have not driven the truck in rain yet and it has been kept in a garage. The carpet itself wasn't wet because the rubber prevented it from soaking through and so was never noticeable until I had the side plastic panel removed and was able to lift up the edge of the carpet. I pulled all the carpet up to the second row and have towel dried the floor and am letting it air out. There are small areas of rust in some areas along the edge of the dynamat but nothing major. I cut through the dynamat in portions of the trunk to expose the floor underneath and haven't found any in other areas.

First question. How should I address the area of rust under the window? It is isolated to what is shown in the pictures below and from what I can tell only effecting the more interior sheet metal and not the exterior body sheet metal. I ran a hose along the top of both rear windows and both are leaking. The left side fortunately does not have any rust but this was the side where the standing water was on the floor and where more moisture was under the carpet overall. How would I go about addressing this on my own? I don't want to start pulling the window gaskets and taking the entire window assemblies apart without knowing I'll be able to get a new gasket if needed and seal it up on my own. For the rust I was planning to go over it with a wire brush, rust converter, and POR rust preventer.

Second question. I am now super paranoid that the floor of the vehicle has rust that has been covered up with dynamat. Should I start stripping out the dynamat to make sure? The metal underneath seems solid throughout the floor.

 

[Hornd]

Hole under Window needs address by a Professional unless your good with Body Work.
Look Up Fluid Film if you want to prevent rust in future.
You need a compressor to spray it unless you want to buy $10 cans at Autozone and spot treat.
It stops rust, but does not make it better - greasy metal does not rust. It should be applied annually.
Tons of guys give theirs annual underside baths and swear by the stuff. I'm sold on it.

 

[MoJ]

The root cause of the corrosion is most likely the exterior belt molding below the rear window. Simple to replace. To stop the rust the rear windows will need to be removed and the rust cut out with new metal welded in. The windows are not difficult to remove. The repair work is relatively minor. I doubt the floor is rusted out but it wouldn’t be a major job to remove the sound insulation and verify. Or, at least remove it in a few areas to verify. Don’t sweat it, if the rest of the truck is corrosion-free this is something you can overcome.

 

[nodor]

I did some more investigating. On the right side I found small leaks through the holes for the belt moldings. The bigger issue is water draining through the window unit that was not draining properly and building up along the bottom part of the body window cutout. This is what is causing the rust. There are holes in the bottom of the window unit through the inner rubber gasket, metal window frame and outer rubber gasket that appear to drain water onto the body just above where the belt molding is. There was a ton of dirt caked in this area and under the belt molding where water is supposed to drain. The question is do I just clean out where the belt molding is and around the window and hope that it drains properly? Should I just seal up the holes in the window unit so water doesn't drain into this area period? Do I really need to cut out the area of rust and have a new section welded in? Is it small enough that I could use a rust converter and paint over it to protect it from further rust? I've seen the replacement gull wing windows. Would this drain better than the stock window?

The left side is definitely leaking through the rear quarter vent. I haven't began taking that side apart yet though.

Window unit removed. Had already cleaned up the area under the belt molding before taking this picture.

Holes in the bottom of the window unit. The window is sitting on top of the outer rubber gasket that fits around the window unit. The holes on the right sit directly above the area of rust.

Looking down through the holes in the bottom of the window unit.

Also, my apologies for the size of the images in the first post. Didn't know how to make them smaller when I started the thread and at this point it won't let me go back and edit it.

 

[nodor]

More pictures attempting to show the extent of the rust.

 

[Sandy Cruiser]

Cut and weld new stuff in. It will be easy to hide the work in that spot thanks to the plastic covers. The pinch welds on the lower part of the window frame are probably rusting from the inside out as well. I have rust in all these spots.

Also look down into the body behind the fender well for rust. You might need a mirror to get a good look.

 

[nodor]

Cut and weld new stuff in. It will be easy to hide the work in that spot thanks to the plastic covers. The pinch welds on the lower part of the window frame are probably rusting from the inside out as well. I have rust in all these spots.

Also look down into the body behind the fender well for rust. You might need a mirror to get a good look.

Thank you. Any recommendations on finding a good body shop? Cruiser Corps is here in OKC and they do body work. Planning to take it up there this week to have them take a look.

 

[thelal]

make sure to clean out all the window and that means taking out the glass and rubber inserts. You'll find a lot of crap, dust etc. and it can react with the metal casing causing pitting and holes. The rubber membane can be cleaned in hot water, suds etc. but may need some serious scrubbing (thats are scrapping out all the dirt). A very strong compressor will help

 

[nodor]

make sure to clean out all the window and that means taking out the glass and rubber inserts. You'll find a lot of crap, dust etc. and it can react with the metal casing causing pitting and holes. The rubber membane can be cleaned in hot water, suds etc. but may need some serious scrubbing (thats are scrapping out all the dirt). A very strong compressor will help

Thank you! This is exactly what I did. Windows are back on and no leaks!

 

[thelal]

Here's some of the nastyness I found and cleaned version

 

[thelal]

few more

 

[thelal]

Heres pics from rear left lower quarter panel with rust and treatment (did soaking in Kurust after lots of scrapping and then several coats of primer 'paint' and spray)

 

[nodor]

Nice! My windows weren’t as bad as yours! I ended up not having the metal cut out and replaced as I would like to see if it progresses after addressing it myself. Cruiser Corp said they have enough parted 80s they’d just cut out the necessary section from one of those if needed in the future. I might do a full repaint in the future and wanted to see if I could wait until I was ready to do that. I ended up going over it with a wire brush and sanded it. Treated with Corroseal and filled the defect with JB weld StealStick puddy and sanded it smooth. Primed and coated with POR15. Turned out pretty good. Hopefully it works for awhile.

 

[MoJ]

Bet that will be just fine.

 

[Malleus]

That repair looks nice! As long as there's paint on the steel, you shouldn't have any more problems.

I preemptively replaced my rear frames and seals last summer (they are both still available new), for just this reason. The frames were corroded beyond repair and the rubber was 20+ years old, so both are now new, along with new belt molding, which I'd bet was the root cause of your problem. It was mine, anyway.

I wouldn't worry about the seat belt anchor holes. The FJ40s have holes in the floorboards and it doesn't cause any problems (those floorboards rust out for other reasons). If you're really worried them, put a bolt in them. If you had water under the Dynamat, and it looks like you did, it'll have to come up and the surface will need to be cleaned. I can see rust near the tie down anchors, and if it's there, it's under the mat. If you wait until you see rust on the lower side of the floor panel, it's too late.

I'd also look at your rear lift gate seal. It's also 20+ years old.

 

[nodor]

That repair looks nice! As long as there's paint on the steel, you shouldn't have any more problems.

I preemptively replaced my rear frames and seals last summer (they are both still available new), for just this reason. The frames were corroded beyond repair and the rubber was 20+ years old, so both are now new, along with new belt molding, which I'd bet was the root cause of your problem. It was mine, anyway.

I wouldn't worry about the seat belt anchor holes. The FJ40s have holes in the floorboards and it doesn't cause any problems (those floorboards rust out for other reasons). If you're really worried them, put a bolt in them. If you had water under the Dynamat, and it looks like you did, it'll have to come up and the surface will need to be cleaned. I can see rust near the tie down anchors, and if it's there, it's under the mat. If you wait until you see rust on the lower side of the floor panel, it's too late.

I'd also look at your rear lift gate seal. It's also 20+ years old.

I’ve been pulling up different sections of the dynamat including those areas you mentioned. Planning to treat those areas as well. I did end up pulling the rear hatch rubber like you mentioned and replaced the rubber. There were definitely a few rusted areas under the rubber that got similar treatment to the areas around the windows.

Before with the rubber pulled

After with new rubber installed. Didn’t get pictures of the process inbetween. Wire brushed and sanded. Treated with corroseal and coated the metal rim with POR15 followed by a white color matched top coat.