I recently upgraded to a nice, low mileage, rust free 3rd gen. I live here in Iowa and see so many of these 3rd Gen's with rusted out rear fenders. I want to know if anyone has any tricks or suggestions to prevent this. I try to wash my vehicles as often as possible in the winter and summer also. Is there anything else I can do to try to prevent this rust??

 

If you dont have them, install full inner wheel well liners on the rear. Most did not come with full liners and allowed dirt/salt to collect and build up inside the inner fenders above the wheels. I have an 03 and installed these when new. I take them out yearly when I get the truck oiled. (5 minute job) And put them back in once the truck is oiled. I have zero rust perforation on my rear wheel openings. I do have a spot about the size of a quarter around the wheel well lip where surface rust has started from a stone chip....but the truck is over 10 yrs old now...and has been driven every winter in salt/snow conditions.

 

A body shop guy told me he's done a lot of box side replacements for our trucks. He said the problem is that a "lip" or something where two pieces of metal meet right on the edge of the fender was not sealed well. When he installs them he uses more adhesive on it to seal it well. My truck is so far gone that I gave up on replacing the box sides. Make sure you take the truck through a wash once a month and it'll help keep it nice.

 

I've read that it's due to the adhesive used where two pieces of metal meet. The adhesive supposedly was spongy and soaked/retained water.

 

I had wondered about what caused it. I figured it was something from the factory. Dogman, I have heard mixed reviews of the inserts. You oil underneath once a year? Maybe that makes the difference. How do you oil? with a spray bottle and a rag?

 

spray under coating In an can works great. I sprayed my 04. I spent 10yrs in Maine and 6 in Wa state no rust.

 

Here in Ontario, Canada we have rustproofing companies that specialize in oil undercoating. The particular business I chose is almost like a car wash. Vehicle is put onto a roller track and pulled along while spray jets coat the underside of your vehicle with oil. Three or four workers then finish the job with spray guns and spray guns with wands to finish up inside doors, rocker panels, wheel wells etc. Companies are governed by the environmental protection act. And yes, smoke from burning oil on your exhaust system does occur on your drive home. LOL

And your probably right, my success is no doubt a combination of the wheel well inserts and oil undercoat. I usually get the oil undercoat done every fall. When I take out the rear wheel wells, usually there is still an oily surface up in behind the wheel wells.

 

I know on my 04, there are a couple pretty large factory stamped holes in the wheel well that let all kinds of dirt and water straight into the area you see rusting out. Its like they designed it to rot.

Other place to keep an eye on is the backside of the rockers. Factory put tape over the stamped holes... I've seen the tape come off, and then water can easily get inside and cause rust.

 

I have an 03 that has held up Great but I think I see a couple spots on the rear fenders now... sucks.

 

Another cheap thing to do, is ALWAYS spray out your wheel wells during the winter. Get the de-icer and salt the hell out of there...... when it sits over time, that is the real cause of the rust issues on all cars.