Is truck bed liner an effective rust preventer?
 

All the DIs up here in Minnesota are rusting. Even ones with only 50K miles at least have the rust in the door frame/rear fender & the door sills. I've read that the DI's steel parts are not zinc galvanized steel, contributing to the issue.

So my question is, if I found a rust free sample from a warmer climate, & had the underside, inside the fenders & the lower door frames coated with truck bed liner, would this be an effective rust preventer? It would certainly make spotting rust nearly impossible, but that's not my goal. I want to keep the body intact for as long as I can, while keeping the body as low maintenance as possible.

The problem is, once the rust starts, it must all be treated and removed prior to coating it with some under coating.

No. Even if you have a little rust, it will just mask it. The rust comes through the body and usually doesn't start as surface. The liner will mask and then make the rust worse.

If you want to coat it, use the black wax treatment they put on the frames of new trucks.

How about this? http://www.roversnorth.com/store/m-19-waxoyl.aspx

Nope, the only things that really work are to strip, then dip, the car like this ->

Attachment 47605

Or to cut out the offending rust and weld in new metal (and hope you got it all)

Or to use a grinder to get the worst of it, and then a paint-on solution like POR-15, which actually reverses the rust process and turns the rust back into metal. Sort of. :-)

When I do a vintage Porsche, I do the strip and dip, and have it put through a reverse electrolysis process to absolutely 100% STOP all the existing rust. I then use a high grade primer and paint, and feel reasonably safe in the knowledge that it took 50 years for the car to get this messed up, so I'm probably good for at least another 50...

The Brits may have invented rust, but the Germans *perfected* it...

X2 Stan. POR-15 on the frame, most of the guys on IH8MUD.com swear by it. Prevention is the best medicine.

I'm guessing if you had the underside Line-X'ed you'd probably be safe assuming good prep work was done and there were no cracks in the Line-X for moisture to slip in.

Speaking from experience, do NOT use any rubberized undercoating unless you have treated the metal underneath It will trap moisture inside and accelerate any rust problem.

The intention was to obtain a rust free DI & then treat it. I'm thinking I just might move over to DII territory. They hold up much better around here.

Bed liner will only trap the moisture in and make the rust even worst. My frame is ridiculously rusty, it is flaking off. It looks like it had some sort of black undercoating sprayed on at one point in it's life. The rest of the truck is fine though. I thought about POR-15, but it seems like it would be hard to reach every part of the frame without taking the body off. I'm thinking of going old school and spraying the frame with something like warmed up bar and chain oil which should penetrate places I can't reach. I've found "fluid film" to be awesome stuff for rusty small applications, but it's pretty expensive.

I live in WI and very familiar with MN so I know your plight. Disco owners in Michigan and the NE experience the same issues. A very simple solution is probably already underneath your Disco. Oil. This is what the old timers did, and it works (Hey, guess what, Grandpa really did know what he was doing). Inspect your fame crossmember by the transmission and under the motor. Scrape off the oil and you'll find it probably looks like brand new. I've lightly applied oil in strategic places on my old vehicles for 20 years (usually just door bottoms and back of frames). It works. It's cheap too. Is it environmentally friendly? Well, don't put so much on that it 'runs' all over the ground. Hey I worked in a body shop for years. There are some gels, but at the end of the day, to apply that stuff to a frame and all over, it isn't practical. And you can't get POR15 inside your frame (I'm not a strong advocate of POR15 anyway).

Oil allows you to apply where needed and each year or two as you re-do it, you can monitor the situation and see how things look. Most folks wait until the problem has progressed too far, then it's more intensive to repair. If you apply it conservatively, you won't notice it from a daily driving perspective and underneath won't be highly messy when you make repairs. That's what you want to strive for.

The best thing is to thin the oil a little with mineral spirits or something not highly flamable. Then spray using an undercoat sprayer which you can buy off Ebay or somewhere, and spray inside the frame and outside. These have the advantage of having a wand and small, flexible nozzles that can be inserted into holes and cracks for better pennetration and ease of application. Cheaper still and very similar is an aparatis that uses air and has a resivior and sprays the oil like http://cgi.ebay.com/BRAND-NEW-Body-D...item439df85c9e. You could take off the tip and put a 3' hose on it and move the tip to a 10" wand (think brake line) that could be easily inserded deep inside your Disco's frame. Once applied, if you then drive the vehicle around a dusty gravel or dirt car lot or road, the dust will stick to the oil and that's even better. It'll dry and form a coat and then it won't get all over you when you are under your vehicle. If you don't want to get fancy, put oil in an oil can and start squirting. Do all the rust areas in and around your frame and at bottom of your doors (from the inside). Spread it around with a brush and catch any drippings with newsprint. This takes about an hour and a half. If you do this every other year (or every year) you will make a huge dent in the rust situation and prolong your vehicle. And the doors won't rust. I have several older cars and the doors never rust on them. But don't wait until the rust has already don't it's damage.

Also, let's not forget about preventative action. A little prevention can go a LONG way, right? When possible, refrain from driving your rig on really slushy/salty roads until they dry up (take your beater car). When you get a nice day out, even in the winter, hook up the garden hose and liberally spray underneath to remove the salt as best as possible. Don't rely on the 'undercarriage wash' from a car wash, they don't do anything ...just a couple small streams of water. Don't park you Disco in a warm garage when it's covered with wet winter salt. A lot of people do this cause it's convenient, but electrolytic action occurs extremely slowly in cold temperatures. Move the vehicle to a warmer space and it increases dramatically. Wash the vehicle in/out on first days of spring - don't let salt hang on the frame and creavices until June. I've heard guys that will put a sprinkler under their trucks for a couple hrs and gradually move it around underneath to get different spots.

I have a 98 Disco that I bought in CA and I simply mothball it for the winter. I have a Jeep Grand Cherokee for that. It's still in great shape. My inlaws bought a used Kia Sportage a couple yrs ago that had a really rusty frame. First thing I did was to brush and squirt oil on and inside the frame. It doesn't seemed to have gotten much worse in the last couple yrs. Good luck.

It finally makes sense! Land Rovers leak oil for rust protection! Thanks for the info Mark.

I'm am confused about mothballing your Rover in the wintertime for your Jeep? Seems backwards;)