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Good Undercoating/Rust Prevention Methods?

Subzero

NAXJA Forum User
Location
Virginia
Hi everyone, just joined the forum after buying my second XJ I've owned. This one is a 1996 Cherokee base model 4.0 4wd and it will be my new daily driver , alongside a 1972 F100 I'm fixing up for a weekend driver. My previous XJ was a 1998 Cherokee that I immediately regretted selling earlier this year. I'm looking to do some work to bring my 96' up to modern times and keep it going for years to come. First thing I'm trying to tackle is rust prevention on the unibody undercarriage. There is very little rust on this jeep for what I've seen in my coastal part of Virginia and I'll get pictures up as soon as it's back from the window tint shop. Is their any recommendations you have for keeping these rust free even in unfavorable conditions?
 
I thought that was why jeeps always leaked oil. It keeps everything covered.:jester:
 
I recommend doing one or both of the following. POR 15 and Fluid Film. POR 15 to treat any rusted areas or put a layer of protection to keep them from rusting. Fluid Film to keep things from getting worse. I am always wire brushing under my Jeep and applying POR 15. Just replaced my entire exhaust so while everything was wide open in that area went to town with the POR 15. POR 15 requires some prep. Cleaning and degreasing then using their Metal Prep before brushing on the POR 15. POR 15 works best on areas that have surface rust on them already. Some wire brushing and the prep I mentioned above. Prep is not so key when dealing with rusted areas. It is the clean metal areas that prep is more important. Fluid Film is a waxy substance that you can spray on. I do it every fall for the coming winter. They put that crap on the roads where I live. In the spring I power wash it off. During the winter I will run my Jeep through the $5 wash bay but not pay the extra buck for the undercarriage. Fluid Film will eventually wash off. Every little piece of crap will stick to the Fluid Film. It makes working on the Jeep really messy.
 
Fluid Film 100%. It is cheap, easy to apply, and not permanent. My recommendation is to either get a gallon of it or spray from the rattle can into cup of some sort. Then brush it on in the larger areas. For irregular areas or hard to brush spots just use a gloved hand or rag to apply it (e.g. the control arms, steering, etc.). I live in New England. My 1998 XJ came out here after a life in AZ/CO and is still rust free after 3 years.
 
Can't seem to get photos on here right now or know the proper way to do so:dunno:. But I got the jeep back from the tint shop. Most of my rust is behind the rear wheels on the underside of the car(the "floor" part)- it's light-moderate surface rust in the area where there was zero undercoating from the factory. I've got some POR15 sealed up that's a few years old I never opened, might try that. I'm out of the metal prep but realistically I won't apply it anywhere but the rusted areas after wire wheeling them. Then I have some Eastwood Rubberized rust Encapsulator to apply over the POR15 since it needs to be top coated but I don't plan to go crazy with it. Fluid film seems like a winner for the unrusted/factory under coated areas. My XJ will be used once a year on the OBX beaches and is my daily driver so it will see the occasional salt and of course rain. I've got the full skid plate set on mine too which might make undercoating a little difficult.

I'd really like to post up some pictures to show and see what y'all think of the undercarriage better. I got this XJ for $2500 and I think I did alright. It's got a new interior and everything works, good tires/rims, and has been a 2 owner Jeep.
Thanks for the replies so far and I'm happy to be apart of the forum!
 
My experience has been on the rusted areas it hold up pretty good with little or no prep. This comes from using the starter kits with the little 4 oz container for small areas under the Jeep. People say once opened it does not really store well. So the little bit I have left I just slap around. What is the worst that could happen? This is how I know that clean metal needs to be prepped. When I slapped it on clean metal it eventually peeled off. Now I also slapped some, without prep, on my rusty gas tank heat shield about 2 years ago. This past summer I hung a gas tank skid plate. When I pulled off the heat shield it pretty much looked like it did when I first did it. Hell I am pretty sure I did not even wire brush it before I applied it. As far as top coating goes POR 15 when exposed to direct UV light turns an ashy gray. Under the Jeep has not a problem for me. So if you are doing underneath the Eastwood stuff is not necessary IMO. Fluid Film everywhere. Rusted or not. This is not a less is more situation. I use a 1/2 gallon every time. I gunk it good. My buddy bought the Fluid Film gun kit and has a compressor that will run it. The cool thing about the gun kit is one of the wands. It sprays in a 360 degree pattern. I do inside the Uni-body with it. They make a wand for the spray cans too. Never used spray cans to do the entire vehicle so no idea how many it will take. Thinking using spray cans can get a little pricey but then think of the alternative.
 
A gallon of fluid film runs about $40 and the sprayer itself for just the undercoating gun is about $45. With all that it should be enough to keep things good. I bought some prep and ready last night and I should be okay to do the actual rust repair when it warms up a little.
 
I'm a 100% fluid film fan myself, and I honestly believe in it. This year I deviated, and used NH Oil Undercoaters formula. They used to shoot FF, but came up with their own version which also has a black tint.
 
I'm a 100% fluid film fan myself, and I honestly believe in it. This year I deviated, and used NH Oil Undercoaters formula. They used to shoot FF, but came up with their own version which also has a black tint.

Having gone the Fluid Film route the last 3 years and being a fan myself was curious about the NH Oil Undercoaters formula.

I have been applying in October for the winter. Every once in awhile I run my car through the $6 automatic wash bay. Do not pay the extra buck for the undercarriage cause Fluid Film will eventually wash off. Then washing it off come April. Primarily since I am still doing work under there and Fluid Film makes working under there messy. My thinking is when I am done working under there, not that you ever really are, I will wash off and reapply every April.

So what are your thoughts on this stuff? I am noticing it is more expensive then Fluid Film online from them. Can't find any dealers other then Napa's in NH. I pay $32 for a gallon of Fluid Film. Through the Napa I work at. Have to check to see if I can get my hands on some of this stuff through my Napa. The black tint is interesting not that it really matters though. Is this something that will eventually wash off? Tough to tell from the info on their website. Looks like the gun kit is so much more expensive then the Fluid Film one. That costs $99 with 2 extension wands and 3 quart containers. Not to mention the wand for the spray can is $18. The Fluid Film ones I buy are $7. Not that any of that matters though. They spray that crap on the roads where I live, my Jeep is pretty pristine underneath considering it is 17 years old, and I would pay more for a better product to keep it that way. Any insight would be appreciated.
 
I run fluid film liquid through a cheap HF airless sprayer for most areas. Places like floorboards, wheel-wells, and the front diff cover get the extra thick fluid-film AR brushed on in hopes that it will last a little longer in the salt-spray. A spray can of the liquid gets sprayed inside the doors and lift-gate.
 
Drop the tank and por15 the entire undercarriage. Make sure you use it in the door jams and bottom insides of the doors themselves. The rocker panels and bottom 4th of the doors would benefit from some herculiner if you have a paint color that will work with it. After that its a matter of stuff like fluid film and going to a car wash with jets that clean the undercarriage after every snowstorm
 
I'm happy to see that more and more folks are using fluid film... I actually started with Waxoyl, but its harder to find and expensive. Here in MA, the aerosol cans are over $14 last time I checked at Autozone, but I've actually found them cheaper at Lowes- $9 per can. I use the cans for touch up and in the doors and hard to access panels.

So yes, I used the NH oil Undercoaters this year. I had been speaking to those folks for a couple of years now, they used to shoot fluidfilm, but came up with their own formula. Not a plug, but an honest opinion. They seem to be great folks and have been in the market of protecting trucks and cars for years, so I trust their opinion. I shot it with the gun I got from FF, and it went on just fine. It does seem to be somewhat thicker, and does not have the lanolin smell (not that it bothered me). Since October we haven't had much snow on the Cape but plenty of sand and salt on base. The NH formula does seem to cling a bit more when exposed to water.

The real proof will be in the spring when I powerwash the undercarriage, I will be sure to keep you posted.
 
I run fluid film liquid through a cheap HF airless sprayer for most areas. Places like floorboards, wheel-wells, and the front diff cover get the extra thick fluid-film AR brushed on in hopes that it will last a little longer in the salt-spray. A spray can of the liquid gets sprayed inside the doors and lift-gate.

When you say the cheap Harbor Freight sprayer do you mean this one?

http://www.harborfreight.com/5-gph-electric-paint-spray-gun-62267.html

I go to my buddy's house and use his compressor and gun kit to apply Fluid Film. I always wondered if that Harbor Freight sprayer would run Fluid Film. It is not a problem doing it at my friend's house but I figured that gun and spray cans with the wand would make it so I would not have to bug my friend. Would not be quite as cheap as using his equipment and just buying gallon containers though.
 
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subbed if that cheap HF gun would really work. Same as ralph Im curious if it actually pushes something that heavy. I could use my compressor but I'd have to swap out to a drier setup from my oiler setup I primarily use.
 
Ralph77: That is the one. I bought it thinking it was cheap enough that if it only lasted one season I'd be doing well. It has been 3-4 years doing 2 vehicles no problem.

I doubt the marine stuff (Fluid Film AR) would go through it very well though.
 
Ralph77: That is the one. I bought it thinking it was cheap enough that if it only lasted one season I'd be doing well. It has been 3-4 years doing 2 vehicles no problem.

I doubt the marine stuff (Fluid Film AR) would go through it very well though.

Thank you posting. But now I am a little confused. For starters I did not catch when you first posted about the Harbor Freight Sprayer that you say you brush on Fluid Film AR. Was totally unaware that there was more then one type of Fluid Film. When I googled Fluid Film AR I came across this:

http://www.fluid-film.com/products/liquid-ar/

No idea that there were 7 different types of Fluid Film. As I stated before started using it about 3 years ago when we started selling it at the Napa I work at. My guess is I just use regular Fluid Film. The first one at the link above. Is this the one you spray through the cheap Harbor Freight sprayer at the link I posted before? If so I will run out and buy one. Thing is that I can't find any part #s on the gallon can I have. So I am unsure of which one I am using. The spray cans I buy, which I am assuming is the same stuff, have a part number. AS11. So I found this link:

http://www.kellsportproducts.com/

If you scroll down a bit they show 3 pictures of Fluid Film. Liquid A, NAS, and AR. Pretty sure the NAS is the color of what I use. The NAS is the one that will spray through the Harbor Freight sprayer? So now I am wondering if I should follow your lead and start using the AR in various places.
 
The stuff napa sells is what will go through the sprayer (NAS). I had to order the thick stuff from somewhere, maybe the link you posted. On a lifted xj, the front axle is exposed to the full 70mph salt spray so the liquid doesn't seem to stay on for long. AR applied with a paint brush lasts longer.
 
The stuff napa sells is what will go through the sprayer (NAS). I had to order the thick stuff from somewhere, maybe the link you posted. On a lifted xj, the front axle is exposed to the full 70mph salt spray so the liquid doesn't seem to stay on for long. AR applied with a paint brush lasts longer.

Thank you. Cheap Harbor Freight sprayer here I come. Also going to seriously consider using the AR type in some areas.
 
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