WTF? Bad metal, factory flaw in the floors???

Picked up a 96 XJ Sport to use as a daily driver. Runs perfect, clean interior, exterior was incredibly clean and not a speck of rust even on the undersides of the rear quarters or under the rockers. Gave it a quick glance underneath and saw some scaling on the floor, nothing major...or so I thought.

Got it home, pulled up the carpet to start running cables...WTF??? (I'll post pics of this) but not only is there rust, but it's eaten through a lot of the areas bigger than my fist all along the framerails front to back. The rear cargo area is entirely non-existent except for the center section. The thing that strikes me as odd though is how localized it is to the framerails, BUT the framerails are perfect, no rust. In some of the worst spots of the floor where it's all gone, the top of the framerail is shiny and untouched. Heck even where the wheel well and rear quarter panel are spot welded to the floor, no rust on them at all, clean as a whistle, but the floor pan is rusted right off it. No rust in some of the low spots of the floor where water would collect either and in high spots...huh? It's almost as if the floorpans were not treated prior to installation, there's no seam sealer or undercoating of any kind underneath.

Heck my 89 with double the miles and leaky door sills has had an indoor pool at times and hardly has a speck of rust on the floors. Anyone else see this? Going to do a complete replacement front to back.

Oh and it's got a clean title, Carfax showed it was registered every year, AC serviced last year so someone was driving it and not a clue to the condition of the floors.

My '95 XJ was exactly like yours, except I didn't find the rust by pulling up the carpet first, after I bought it, I tapped and scraped the light scaling on the underbody, trying to clean up what appeared to be light surface rust, entire sections of the floor fell out. Then I pulled the carpets and started the cutting and patching job.

this is common to vehicles that have been flooded, then dried out without removing/replacing the carpet. moisture just sits in there between the carpet and the floorpan and slowly eats away your floor. cars usually get totaled out because most of the electricals are such are lower to the ground and get affected more by the water. most trucks will sit high enough above the water that people will just keep em and dry em out if they still run. your truck might have been flooded or rained in excessivly many years ago and you're just noticing it now.

It wasn't flooded. That is like all mid 90s XJs. I too had an older 87 with some rust, but none on the floor and 300k. I pick up a 96 with 120k. Good quarters and solid rockers BUT NO FLOOR when I pulled the carpet. The floor metal is thinner than the older models and lower quality. Mine sounds exactly like yours down to the pristine frame rails. It's a shame DC cheap skated on the floor. Also, the common leaks found in the XJ (AC tube, heater seal, windows, hatch...etc) do nothing but help trap water under the carpet and help rust out the floors. Good luck with the repair. I suggest getting replacement panels. I went the 18ga sheet metal route and spent days getting it to fit correctly. Make sure you get the rust in the cubby holes behind the rear wheels.

Yup, it's a common problem. The floor in the passenger footwell of my '93 rusted - and I had been driving it in desert-dry conditions (no floods!). I suspect the aircon drainage tube had leaked or got blocked and gradually soaked through that horrible soundproofing/underlay stuff under the carpet - then the rust had slowly but steadily attacked...

Got a bodyshop to weld in a patch and rustproof both sides, and I threw out the rotting underlay. But now it's a regular routine check - take out seats and carpets and check the floors.

I noticed that one US parts dealer (Discount Jeep Parts) was selling complete replacement floor panels (left/right, front and/or rear). So there's obviously a demand for them!

Good luck

br1anstorm

As far as the carpet and floorpan is concerned, whats the difference between being flooded once and never dried out properly,

OR,

never once vacuuming the carpets, nor using floor mats and spilling soft drinks keeping it constantly moist between floorpan and carpet for a dozen years.

Well, the 2nd will never show on a carfax report. All of my rust spots were at the lowest points of the interior of the floorpan, where spilled liquids would pool. The largest Rust Hole, by a factor of 3 was just below the inadequate factory cup holder that was next to the shifter. I'm confident the rust for that hole came from spilled soft drinks.

When I cleaned the carpets, I spent 4 hours with each, scrubbing with a mixture of Simple Green/Detergent/OxiClean and running the hose into them the entire 4 hours, the water ran out muddy the entire time, I could only get the rinse water down to slightly tinted mud brown at the end of 4 hours when I gave up. That is how dirty the PO kept the interior, and I'm sure that was the cause of the Rust Holes.

Flood was my first thought, but it wasn't localized to the low spots of the floor, 90% of it is right above the framerails and many places where seams met. Even on an uphill slope of the rear part of the pan. No silt, no smell and no signs of corrosion in any electrical. I'll snap some pics maybe tonight.

Right now the plan is to strip out the entire interior except for the dash and windshield. But the doors, hatch and side glass will all be removed. (Was going to take them out to tint anyways). Brace up the framerails underneath by tacking some 2x2 rockrail cutoffs so they don't sag, X-brace that and the B-pillar area inside. Then get busy with the spot weld cutter and bodysaw and have some FUN! Floorpans so far aren't that bad for price- $165 shipped for the entire front section and $153 for the rear. Two pieces, cool. I'll only rip out one section at a time, probably the front first, then tackle the rear. Fun fun fun.

When I got my 88 I knew it had some rust. I saw a small hole in the floor so I pulled the carpet and it went from a small hole to a big hole. It still isnt done but its better then it was.

I am still working on patching my '88 Laredo's floor. It rusted out quite badly under the drivers' foot area. The patch ended up being about 15"x16". The rust hole goes all the way over to the kick panel area, but fortunately, had not started eating the kick panel area yet. The other direction is almost to the edge of the tranny tunnel. Length wise, this thing goes from just above the factory overlap (which is NOT welded together, by the way, just seam sealer), to 1/2 way back to the seat. Don't forget the plug (rosette) welds when you patch over the frame rails.

Make sure it is braced!!! Keep it level (if possible) and supported at whatever position you have it at when you remove the floor pan. If it not supported, when you open the door you will lose what ever ridgidity you had and the "frame' will sag or bow....I know from experience.
My 90' currently sits leveled, on 8 jackstands, sitting on 1 1/2" steel plates to help from sinking in to the ground, checked them the other day after sitting all winter...still level without any floor pans.
If you can, before you remove the floor pans, get some sort of bracing between the B posts, even a ratcheting strap would help to keep the sides from bulging out, as soon as the pan is removed the sides WILL try to bulge out. Do this in the rear too. The top of the "dog leg" area is a good spot.
Good luck...it is a $uck job but it can be done and you'll get many more years of fun from your XJ.
PS. Make sure you lose the "cancer carpet", don't know what they were thinking when they designed that crap.

Passenger side will always rust more due to the exhaust below it...

I'm sure the heat from the exhaust doesn't help, BUT, my worst holes were No where near the hottest parts of the exhaust, the floor over the Catalytic Converter was in perfect shape.

My 94 looked good when I picked it up. couple weeks later, I noticed the carpet was always damp. I pulled it in the cargo area, but the floor wasn't so bad, so I cleaned it up and put down bedliner. Couple months later, I pulled the rest of the carpet, and the floor was in ruins. Driver's side, passenger's side, and right under the jack above the muffler were the worst. This is my DD, so I pulled it in the shop right away, and went to town with new plate and bedliner to finish - had the whole thing done in 3 days.

That carpet is like a filthy sponge, you should have seen the bottom of it before it hit the dumpster.

Rick Anderson said:

I'm sure the heat from the exhaust doesn't help, BUT, my worst holes were No where near the hottest parts of the exhaust, the floor over the Catalytic Converter was in perfect shape.

Click to expand...

I was just speaking from experience, for my Jeep anyway. However the hot exhaust does cause rust to grow quicker due to the constant heating/cooling of the metal.

Yes, I think its more the heat breaking down the protective coat and increasing the speed of the chemical reaction of the rust (oxidization).

Its usually the bulky and very hot Catalytic Converter that is close to the floor that heats and gets the floor rusting.

I'm sure there are Jeeps rusted out from exhaust heat and its very common on other vehicles, BUT in my case and it looks like a lot of the others, its more the moisture getting trapped under the carpet.

There is lot of stuff carfax won't ever show. It only shows what is reported to DMV's and insurance companies. Not all accidents, flood damage, and few if any major hardware problems ever get reported to the sources used by carfax. Just think for a minute about all the stuff we do to our Jeeps that never gets reported to insurance Cos or DMVs. Once a car is about 6 years old it is not worth insuring with comprehensive insurance and so major repairs and damage may go unreported by doityourselfers like us because there is no reason or need to report it. Engine swaps, tranny swaps, drive train swaps, replaced, rusted floor pans......One can tell the minimum number of known owners, and major stuff in the first few years of ownership, but after about 6 years of age the rest is prety much useless as it is very likely to be very incomplete.

I know that some parts of the country, up north, where they use a lot of road salts for de-icing the roads, and coastal beach (salt water) areas are bad about early cancer rust deaths, but down here in Houston, we regularly see nearly rust free vehicles as old as 20 years old, but I am also wondering and thinking that there was a major change from galvanized steel (which I think my 85-87s have, at least it looks like they have galvanized coats under the paint, and they seem to be nearly rust free) to electrodepostion of newer (& less expensive, more environmentally friendly and Osha safer) electrophoretic primer coatings.

http://en.wikipedia.org/wiki/Electrophoretic_deposition

Quoting from the link above: "The first patent for a cathodic EPD product was issued in 1965 and assigned to BASF AG. PPG Industries Inc. was the first to introduce commercially cathodic EPD in 1970. The first cathodic EPD use in the automotive industry was in 1975. Today, around 70% of the volume of EPD in use in the world today is the cathodic EPD type, largely due to the high usage of the technology in the automotive industry."

Does anyone know when Chrysler switched over from electrogalvanizied dip to the cathodic electrophoretic primers? The older bodies with the zinc-galvanized primer should be superior as far as corrosion resistance goes.

Lastly, the electrophoretic primers are superior to simple iron or zinc phosphate primer coats, unless they were followed with a chromate conversion coating which is being totally eliminated now (Hex chromate conversion of zinc phosphate primer) due to the new European standards that already went into effect a year or 2 ago. I think AMC/Chrylser went with the electrogalvanizing in the mid 80's as a quality improvement step to out do their competitors under Iacoca (sp?).

Does anyone know when Chrysler switched from electrogalvanized zinc primer to the electrophoretic primers?

Oh, and by the way, inorganic zinc / galvanized steel primer coats are not affected by heat (cats and mufflers exhaust) like an organic electrophoretic primer coating would be affected. The old (inorganic) chromate conversion coating is also not affected by the heat though any organic top coat might be lost to heat damage.

that is EXACTLY how my 96 is. damn you new england! This summer ill be replacing everything floor-wise.

The floor rust being more prevalent near the joins with the C-Channels or Frame Rails?

I'm guessing one of tow reasons or a combination of both:

*Some sort of galvanic effect with a circuit with a different thicker steel piece, the C-Channels and other structural pieces re-enforcing the floorpan are definitely thicker, maybe even a different steel with a different metallurgy. That may set up a galvanic effect where the floorpan becomes a sacrificial anode in a way and rust sooner and faster. OR it could just be the thinner metal rusts through faster than the thicker (duh).

*The joining of the floorpan with the C-Channels and re-enforcing pieces leaves little gaps, nooks & crannies and ledges that water and dirt can collect and remain trapped there much longer than the rest of the floorpan. The longer exposure to water and dirt, breaks down the protective coats and starts the rust.

When I finished patching up the floorpan, I took Auto-Body Sealant and sealed the edges of the patches (top and bottom) but also went around the whole underbody and sealed up any of those nooks & crannies, crevices that could collect water/dirt and trap it there. Then I did 2 coats of rubberized undercoating.

This problem travelled across the Atlantic also, most pre facelift XJ's suffer seriouse corrosion on the floor pans. You can find first class low milage trucks that are scrap because of rot. When I replaced my fuel tank a few months ago the boot floor above was bear metal, no wonder they rot.