My truck is going to see it's first winter with salt on the roads. The framerails and all panels are rust free. Shouls I spray undercoating in the fenders, frame rails, etc to protect them, or would this just trap moisture?

 

I feel that undercoating is a good way to prevent rust. My 82 F100 had the underside undercoated when it was brand new. Even though it has rust, im sure it would of been alot worse if it wasn't undercoated. If you don't want to use undercoating try a rust preventative paint, like zero rust. Good Luck Fred

 

I'd rather use the paint. Putting undercoating on an old frame can trap lots of moisture and rust.

However, the undercoating is nice for sound deadening.

 

So what's the best spray on rust protective paint? I was thinking that the moisture in the air right now would even be a problem if it were trapped under the undercoating.

 

remember that rust needs water and oxygen. trapping moisture isn't a big deal if there are no small holes in the frame (or undercoat) to let in oxygen. Of course, it's better to avoid trapping that moisture, but humid air shouldn't really make a difference unless the rust starts before the undercoating cures. I'd recommend using a basecoat of rustoleum primer or something like that. then apply your undercoating. I've been thinking of doing the same thing to my truck for awhile now. I don't live in a salted-roads area, but the truck used to. I need to clean out all the old rust before I undercoat. At least that's the plan right now

 

Good idea, I think that I'll do the same thing with applying a good coat of rustoleum before the undercoating. A guy at work when I was discussing this said "that'll add more weight to your truck" like that was a really bad thing. Guess that's why he drives an import...

 

if you already have a little bit of rust started they make a rust converter that you can spray on the rust that will turn it into a paintable primer. good stuff! just called rust converter and you can get it at any auto parts store. it also has a rust prohibiter. then use primer and then your undercoating. with the undercoating you get what you pay for so if you want a good undercoating go ahead and spend the extra money for the more expensive stuff.

 

even better than that rust converter is POR-15. if you can get some of that... rust will be gone

 

I've heard of POR-15, but is this something that can be had at a local shop, or a special order item only?

 

POR-15 is available a lot of places. It is definately a good idea to use it, or some rust preventative coating first, then undercoat. If you check my gallery, you can see what mine looked like before and after undercoating. I was lucky in the fact that I did not need to paint-prep the surface first.

 

Being from the north i have seen many under coatings bite the big one after a few years. I'm talking rusty jones, etc. the only thing that was reliable and cheap is oil undercoating it's easy to aply and hydraulic oil is resonably cheap two gallons of oil will coat the underside of the truck nicely and it will stop any rust dead in its tracks use an air sprayer to aply it every year before the snow flys and the salt comes out the nice thing about the oil is that it seeps into all the seems on the sheetmetal and under bolt heads the places paint and undercoating cant get to. I new this one lady who was able to keep a chevy chevet (AKA Rust buckets) for ten years and the only thing that ever rusted on the car was the drivers side floor board where the salt stuck to her boots and then rusted out the floor from the inside. And dont forget to spray in the door panals good luck

 

WheelMA Did you use Herculiner truck bed coating? Was that roll on or spray on type? Also, did you leave the stock plastic guards out of the wheelwells after doing the coating?

 

Yes, I used Herculiner. It was roll-on. I reinstalled the guards afterwards. Although the underside was protected, those guards help keep the noise level down from the road and debris.

 

I noticed that you wrote that you would pay someone next time. Was it that bad, or was it just a mess?

I was thinking about using a bedliner. I saw three different brands at Wal-Mart yesterday and was wondering if it would work. One thing though, they all said that it needed to dry at around 65 degrees. I guess I'll have to park the car outside one night at least.

 

No, it wasnt difficult....it was messy. I was picking clumps of black goo out of my hair for a week . Wet roll on +gravity = . I actually completed the entire project in my garage (heated), and just let it sit for a day. That allowed enough time for the chemicals to flash off.