Been working with on my Jeep some and played with POR15 to patch rust holes for the first time. Wanted to show progress and get your thoughts.
Floorboard Repair:
Let me start with a little public service announcement… 96-01 Cherokee’s have a design flaw in the fresh air intake for the cab. If you remove the wiper access panel just behind the hood and shove a camera in the cowl, here’s the difference.
Early model XJs:
Late model XJs:
There’s a great deal more information here (full credit to these folks for the pictures above as well):
http://www.cherokeeforum.com/f2/water-leaking-cowl-34969/That nonexistent lip on the later model version means that if it rains and your Jeep has the nose pointing at all uphill, you’ll get water that leaks through the cowl and soaks your passenger floorboard. Even using textured rubber floor mats, I’d still managed to soak the carpet half a dozen times before I figured it that nose up was part of the reason why it happened. There are two solutions:
Solution Option 1) Cut through the cowl from the exterior, caulk the offending area and weld a patch back in. If you try this approach you better do it well because if your cut and patch leaks it’s headed straight into the intake.
Solution Option 2) Always park your Jeep with the nose pointing downhill, which is what I’ve been doing since I found out about this mess.
While working on frame stiffeners, I saw some cancer starting to show through the bottom of the floorboard, apparently from the inside. I yanked my passenger seat and pulled up the carpet to investigate. Yikes!
Rust completely covered the floorboard, which the exception of the sound deadening. It’s the only rust on my Jeep that I know of, but it’s bad…
Through holes confirmed.
I got in there aggressively with a wire wheel and suddenly I had quite a few holes showing.
I wire wheeled the bottom side too for good measure and now it was really pretty screwed looking.
A lot of folks jump directly to a reproduction floorboard and cut the whole thing out this point. I thought about that, but sometimes you end up compromising integrity instead of adding to it (seams rusting), and fit can be less than ideal. Instead I decided to try a version of rust conversion and encapsulation from POR-15.
http://www.por15.com/Floor-Pan-Repair_ep_77.html.I figured worst case if it didn’t work out, I’d be cutting out the metal anyways, but might teach me some new methods I could use on the Land Cruiser.
The trick to patching holes with POR-15 is either by using their Epoxy Putty or embedding fiberglass in the POR while wet (effectively using POR as a fiberglass resin). They call it Powermesh. I call it fiberglass chop strand mat and say “I’ll use whatever fiberglass I want, thank you very much.”
Prep maters a great deal with POR-15, so with the exception of fiberglass vs. Powermesh, I tried to follow the process. The recommended steps are:
1) Marine Degreaser, rinse,
2) Metal Prep, rinse, dry.
3) Por 15
4) Top Coat (optional, only if exposed to UV)
Note Por-15s “Metal Prep” is a rust conversion fluid much like “Evapo-Rust” which I converts iron oxide (rust) to ferric phosphate (or similar), after which it can be encapsulated with limited opportunity for future growth. You need to keep the area wet for at least a half hour in Metal Prep. I used a spray bottle periodically for more like an hour then let it sit overnight because I didn’t see much downside to doing so.
Here it is after Metal Prep.
I used three layers of glass: a fine weave to get into the corners, a heavy layer of roving to build up some thickness and give me some strength, then another layer of fine weave up top.
I taped over the holes from the bottom to keep drips at bay…
… and then went to town inside. Paint the bare steel, apply a layer of glass, repeat. I basically painted over each layer and pressed it into all the nooks and crannies as it went down to be sure it was fully wetted out. All three layers went down back to back to back.
This stuff is pretty stinky so ventilation and an organic trap cartridge mask are both good calls.
While still wet, I yanked off the tape from below and painted the bottom side. You could see just a touch of POR flowing through the holes from the topside (blooming effects at the corner of some holes).
Next day went out and it seems to have still picked up some crap as it leveled and flowed through. Maybe letting the Metal Prep sit overnight made it harder to get 100% rinsed. Not really sure.
The imperfections on the bottom side didn’t seem like a big deal as it was still REALLY solid feeling. I then used some of POR 15’s epoxy putty to fill and smooth the gaps where metal was missing. That stuff cures damn hard as well. Sanded it most of the way out and all that’s left to do is one more coat of paint. That’ll happen at the same time as the body frame rails.
Last few note on POR 15… It’ll break down with UV light, so you need to use their Top Coat paint if it’ll see sunshine (step 4 noted above). You could probably paint with anything, but paint is enough of a dark art that I prefer to stick to a single system where I can.
Finally, when capping the can it’s recommended to stick a couple layers of saran wrap between can and lid. If you get any on the paint can seal, that lid is not coming back off.
Oh, and naturally since I limped my Jeep back in the driveway with two ratchet straps in lieu of a track bar, I’m parked nose up. Seriously what are the odds of Southern California have rain in early September? Yep, we had a freak weather day and it already rained once, but I at least I can still confirm that the new area is water tight (that’s one step better than a raw replacement floorboard so I’d recommend POR 15 either way).
Need to retap the holes for my seat and shave down some pointy edges inside, but the major fix looks good so I thought I’d post up. Let me know if you have thoughts on POR 15 as I expect to be using this a bunch more on projects going forward.
-Joel
