under coating

I am a new to owning a jeep, I have a 99 that is less than a week old to me, I was crawling under it last night and noticed that there is no undercoating. Is this common? and I plan on spraying the little rust that is on it with the Napa spray over rust stuff, then undercoating the crap out of it. does that sound reasonable to you guys? I live in Michigan and this is my year round driver.

Dallas

74charger said:

I am a new to owning a jeep, I have a 99 that is less than a week old to me, I was crawling under it last night and noticed that there is no undercoating. Is this common? and I plan on spraying the little rust that is on it with the Napa spray over rust stuff, then undercoating the crap out of it. does that sound reasonable to you guys? I live in Michigan and this is my year round driver.

Dallas

Click to expand...

I live in Northern IN aka Rust Belt just like you.

That rust is a constant battle......

Every one around here has rust on there vehicle.

Most XJ's do not have undercoating unless someone had there sprayed when purchased from the dealer.

What I do is replace the rusted area if rusted a hole, then spray

(not the was-as-dry crap) It is like 7/8 bucks a can but it lasts long.

If you have no holes but just surface rust just take a wire brush and/or a drill power wire wheel and clean the surface so it will stick better. Also make sure you get all the dirt and my case the mud.

thanks, no holes, but some surface junk. I just want to stop it in it's tracks.

Wire brush, primer OR paint, then undercoat. Don't put the undercoating right on the rust.

Wire brush, get some Zero Rust and use it as a primer, no need to top coat it, then spray with bed liner, do it in coats and don't be cheap on how many coats, $20-30 now could mean the difference between $150 floor pan and hours and hours of labor later.
I would buy a gallon and a few cans of spray. You can use Dupli-Color with pretty good results. I'd use the spray to get in the seams, make sure they are totally dry, mask anything you don't want coated but remove the tape b-4 the liner drys or you'll never get it off. Use the gallon on the big spots that you can roll.
Wear gloves, disposable hooded coveralls and a cheap face shield will keep you clean.

Do not use ANY of the "rust converter" products out there. 'Friend of mine and I did his whole CJ frame. About a year later, 'noticed paint peeling. an hour with a scraper had about 1/4 of the frame exposed. Everywhere the rust converter was, the rust had continued. 'Converter didn't do a thing. Funny thing was, it seemed to seal the rust free areas pretty well.

Don't bother with conventional undercoating. Any rust underit, and it will just hold moisturer in. The poly- bedliner stuff seems to work pretty well.

Are you talking about that stuff that kind of makes a "plastic" clear coating over the rust?

I've used that before and it always peels.....straight rustoleum ftw!

"Converts" the rust to a blue/black coat that looks like a thin layer of plastic. Over clean steel it stays clear. Yep, thats the stuff. Total CRAP.

We ended up going with the rustoleum the second time around too. Used the rusty metal primer and a tan top coat. If you don't need a shiny glossy pretty finish, buy the quart or gallon cans. use a 4" foam roller, be careful and don't make a mess. Finished product looks pretty good.

Not only is the stuff crap, it is dangerous. It contains isocyanates. even if you are outdoors you will breathe some of it. The stuff is terrible for your lungs.
If someone sprays their rust and expects it to be magically fixed...they are sadly mistaken and should leave the rust problem to a professional. You might get away with surface rust but nothing that has started to blister.
Even Zero Rust suggest you remove all the rust you can. I use it and swear by it, even knowing what a good product it is I still remove al the rust that I can, even surface rust. I use it to prime with and have no worries about rust
rearing its ugly head again and it does not contain isocyanates.

How is there no factory rust prevention? My 91 looks near new underneath. i know they stopped zinc-plating, but they had to use some industrail cating or similar to keep it in such nice condiion.

Must just be the salt free Tx roads :doh:

Paint....

under my 2000 which i bought earlier this yr there is black "bedlinder" stuff under there and no rust the dealership does this kind of stuff? maybe the first owner did it..... pretty good for NY :cheers:

yeah, I'm attemting to experamint with some of the Duplicolor paint over rust stuff in limited areas. But now I'm going to give up and just wire wheel it all off and do the rustolum thing. That has always worked in the past, but the POR was such a good concept, had to try it. I used the bed liner on my sunfire, and I loved it. and for those of you who were trying to tell me how to get it to look good, I could care less. All that looks good to me under there is no rust.

a little pricey and kinda hard to work with but POR-15 is a good option

I've found the undercoating varies drastically from brand to brand as well as just different levels within a single brand. And, NOT SURPRISINGLY, the level of quality seems to be directly related to the price of the undercoating.

I bought some of the 3M Proffesional Rubberized Coating, that states on the label it contains NO TAR. Boy that stuff was great, but at $8 a can, I couldn't afford to do the whole underside with it. The $3 a can stuff, sure enough, seemed to have a lot of tar and was very goopy.

The $8 a can 3M Pro stuff went on like spray paint, after drying it even looked like a thick coat of flat black spray paint, and it was tough, with a rubber feel to it, but it did NOT give when you pressed on it. The cheapo stuff, even after several days to dry, would rub away easily. The 3M Pro stuff within an hour could not rub away if you tried, you would need some serious tools. You could also tell by the coating, that it was clearly adhering to the metal.

I used the 3M stuff for covering the patches I welded in, and the rest was the cheapo stuff.

I used the el-cheapo stuff. It was messy but not that bad. Some flakes away but it's good enough for me!

Yeah, me too. I prefer the LocTite brand and it does fairly well (compared to the ideal: a complete strip/cut and weld). You just have to do a very thorough job of getting rid of all the loose surface rust you can (the angle-grinder is your friend in these situations) and be vigilant about coating and re-coating. I know it's a cliche but the better prep you do the longer your project will hold up in the end. Yes, a full amputation followed by welding in a new section is ideal but there are other options. For instance, the lower door seams are complete crap on most stock Jeeps and will rust in a very short period of time. You have a few choices; you can either replace the doors, stop the rust chemically (if it's not too bad), or cut out the lower section. There are those on this forum that will say that cutting and welding are the only option if you don't want to go through the bother of getting in new doors from Storks but I think they're just trying to be contrary (since it seems to be the only advice they give regardless of the situation). Living in Iowa I've dealt with rust all my life and if you can catch superficial rust early you can cure it rather cheaply with the chemical systems available. Lordy, if I took my Jeep to the body shop for a full amputation every time I saw rust I'd be flat broke!