Where would you start with the Chief project…

[Jwillis]

Actually I was going to write something like that, but it's been covered sooo many times before.

In my part of the country, this does not look too bad. Actually, it looks pretty good. Lots of dirt mixed with some flaky rust, but the structure looks all there. The longest lasting repair will be all new steel, which will last another 50 years before it's back to the state you see... unless the owner is more effective at keeping the floor dry. Then it will last longer.

Patching it up won't last as long, maybe 20 or 30 years? Especially if the floor is kept dry.

Instead of fiberglass, you can pop-rivet patches over the holes. Use something like the bed liner suggested above or urethane cement or an MCU paint or whatever. Won't last forever, and the better you seal it up and neutralize the rust, the longer it will last. But it will probably last long enough.

Thanks! I’ve searched the forum for “floor pans” and didn’t see anything about this but I probably didn’t dig deep enough.


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[tgreese]

I think that lots of this kind of patching goes on, but nobody reports it. Anything less than new steel compromises longevity, so the only "right" repair is to cut out the rust and replace with new steel.

Understand the problem with red rust. It's an iron oxide hydrate, with a larger volume - molecule to molecule - than the iron in the steel. When the rust is formed, it pulls away from the substrate steel and exposes new steel. Thus the surface is inherently unstable and will progress unless all the rust is removed and the surface is sealed from the air. Alternately, you should be able to leave the rust in place and seal the surface from the air - potentially difficult due to the unstable surface.

In both cases, you need to apply some top coat to keep out the air (oxygen and water). It seems that the longevity of your repair depends on how effectively you seal the surface. The situation where a near-perfect seal can be achieved is on new steel. Compromise the surface with rust, and getting an effective seal becomes harder - I presume.

There are lots of products out there that claim some utility in this situation. Broadly they are rust convertors (which chemically alter the rust) and rust sealers (which claim to seal the existing rust). Do a little searching and you'll find a lot of discussion of this.

(edit - Rust Encapsulator is a brand or rust sealer - all these paints are some kind of moisture cured urethane with a proprietary pigment AFAIK. You could also use something gooey like the bed liner suggested above. Don't use bondo.)

[Jwillis]

I think that lots of this kind of patching goes on, but nobody reports it. Anything less than new steel compromises longevity, so the only "right" repair is to cut out the rust and replace with new steel.

Understand the problem with red rust. It's an iron oxide hydrate, with a larger volume - molecule to molecule - than the iron in the steel. When the rust is formed, it pulls away from the substrate steel and exposes new steel. Thus the surface is inherently unstable and will progress unless all the rust is removed and the surface is sealed from the air. Alternately, you should be able to leave the rust in place and seal the surface from the air - potentially difficult due to the unstable surface.

In both cases, you need to apply some top coat to keep out the air (oxygen and water). It seems that the longevity of your repair depends on how effectively you seal the surface. The situation where a near-perfect seal can be achieved is on new steel. Compromise the surface with rust, and getting an effective seal becomes harder - I presume.

There are lots of products out there that claim some utility in this situation. Broadly they are rust convertors (which chemically alter the rust) and rust encapsulators (which claim to seal the existing rust). Do a little searching and you'll find a lot of discussion of this.

Thanks for your words of wisdom! I’ll update with progress in the coming weeks!


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[letank]

Fiberglass is tricky, better to avoid it as it seems to absorb water. Replacing sheets is the way to go... BUT in your case you have to find out where the water is coming from: removed the fresh air vent covers and clean the nice repository of compost... the dried up window wipes are the 2nd chapter of water seeping in, and third the dried up or missing seam sealer chunks that are buried in the cowl vent structure. For our rainy days in Cal I put a cab/roof cover, as there is always a bit of water under the carpet.

Fresh air vent discovery:



and the related posts:
https://www.fsjnetwork.com/forum/viewto ... f=7&t=7426

and cab cover for rainy days



my attempt with fiberglass, it made it worse



JB weld did the trick, that pict is from dec 2014

[Srdayflyer]

Ok hackers, stop with the band aids on cancer, cut out the cancer floors, ,the passenger floor has a hidden box area that a body mount attaches, and can't be seen from inside or underneath, next I would replace the frame to body isolators as the bolts are probably nearly rusted out and replace them with bl,s polyurethane mounts you'll appreciate that the body won't either slide off the frame or twist off on the trail, also the frame rail between the gas tank collects lots of dirt and mud and the frame rail rusts out , there is a repair kit if you have that condition,also the driver side emergency brake cable rusts out there. Just my take

[threepiece]

I always first do a thorough cleaning and inspection. There are many more dirt collecting areas on a Cherokee than mentioned here on this thread, front shock tower, rearmost body mount and header panel to name a few. All have the potential to rust. I install drain holes on all the areas mentioned when doing a restoration.

I once nearly filled a two gallon bucket with debris removed from the rocker cavities of one Wagoneer! Care should be made not to scratch any paint or primer when cleaning inside areas like rockers or doors. Flood these areas with water to be sure the drain holes are clear. By the way there is a hole in the wheelhouse usually covered with a plastic plug that will allow access to the rocker. Jack the rear, remove both wheels and peek inside with a light.

A thorough cleaning could easily take more than one day especially when dealing with the boxed portion of the frame.

[akguy09]

The other option for the floors, which is what I am doing to my J-10 is cut out the rusted areas and weld in new metal. I cannot see patching over rust, but that's my 2 cents

[tgreese]

Do what you have to do to get it done. Don't let perfection be the enemy of the good.

Any repair will have a finite life. Everybody agrees that new steel is the best repair. However, many of these cars were daily driven on salty roads every winter. Some got rusty, and were delegated to plow service, which was terrible for the car. Unlikely these now-hobby cars will see that kind of service any more. If you want a 4WD wagon to drive all winter, find a decent WJ to drive. There are a lot of them out there, and they are both newer and very much more corrosion-resistant than any Wagoneer.

[rocklaurence]

Jwillis, give us an update and pictures