Preventing Rust in Fender Wells

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I’m always amazed at how many trucks are out there with rusty fender wells. The remainder of the truck is usually just fine. While new trucks are coming out with plastic liners, what type of treatments seem to work to prevent the fender well rust on older models of trucks and cars. Thanks.
 
Fluid film works great and creeps long dstances. The tailgate on my old Toyota was rusting thru at the lowet corner. I removed the inner panel and gave the rusty area a shot with Fluid Film from an aerosol can. Problem solved for about 4 years now.

The great thing about Fluid Film is no special surface prep. Spray it over existing rust and you are done. Vehicles in road salt and chemical brine areas should be sprayed every year. The chemical brine is way more corrosive than road salt.
 
Since you're in Canada, go get your truck sprayed at a good Krown shop. The shop I go to, Krown Sarnia, removes the taillight fixtures on my truck (a '95 Dodge Dakota) and get their long spray wand back to the wheel well area. It's the oil inside the fender, sprayed between the inner and outer fender panels, and that leaks out for a week or so thereafter (and creeps into crevices long after that), that's keeping my truck rust-free here in Saltbelt Michigan. I can't buy much bodywork and paint for the cost of my Krown resprays.
 
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I've driven my 2 Lincolns ('97 and '02) in 17 winters so far. And not a single bit of rust in the wheel wheels or quarters/fenders. Ford did something good with how they under-coated these wells and painted the cars. Very durable. And no rust ever developed into the wheel lips or lower quarters. I hope they're making them as durable today.
 
Rust proofing spray is only as good as the level of contact with metal. Often you will find dirt/mud/buildup inside the wheel wells where the rust typically starts. Be sure to brush away this buildup before applying the rust control fluid.

This "mud" is the main cause of rust, IMO, since it traps moisture for extended periods of time. Whereas dirt/mud free metal would not be exposed to those extended periods of oxidation.

Step 1: clean the dirt/mud away from the seams/lips
Step 2: allow the area to dry
Step 3: apply rust control fluid

I did that with my old subaru, which was famous for rusts in those spots, and never had any corrosion issues.
 
Chevrolet/GMC pickups have been rusting badly above the rear wheel wells and at the rear lower cab corners for 40 years. You would think they would figure out a fix by now.
 
I guess they want you to buy a new truck!
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No more sticky slippery waxes that attract soot, sand, flake off. What a mess, dangerous too. I was underneath putting a jack stand in place and I could see the jack slipping off the frame. That was it for me. I switched to a combo of corroseal and Rustoleum rust reformer spray with tannic (the white bottle). So far, so good. Even if it eventually flakes off at 2 years, thats still so much better than FF
 
I spent 4 hours last summer under my daily driver wire brushing small areas of surface rust on the undercarriage. Applied some Eastwood Corroless primer that I've had around for yrs. Almost all of it precautionary before white flaky stuff turns to brown/reddish stuff. The car will probably fall apart before rust ever is an issue. First daily driver I've ever been this anal on as far as preserving the paint and undercarriage.
 
Originally Posted By: khittner
Since you're in Canada, go get your truck sprayed at a good Krown shop. The shop I go to, Krown Sarnia, removes the taillight fixtures on my truck (a '95 Dodge Dakota) and get their long spray wand back to the wheel well area. It's the oil inside the fender, sprayed between the inner and outer fender panels, and that leaks out for a week or so thereafter (and creeps into crevices long after that), that's keeping my truck rust-free here in Saltbelt Michigan. I can't buy much bodywork and paint for the cost of my Krown resprays.


+1.
 
What surprises me is that owners (of all sorts of vehicles) don't wash the inner side of the rear quarter panel, that part you can get at from inside the rear wheel well. Mud collects up there and if it never gets washed off, it just stays there, often damp and in contact with the sheet-metal. I can't think of a better way to make rust. Well yes I can, if you add a bit a of salt to it that would make it even better.

Check almost any vehicle. Curl your fingers around the lip above the rear wheels. They'll come back dirty. My BMW has practically eliminated that space but almost every other vehicle I've ever owned has a shelf up there that seems like it was designed to collect dirt.

I wash that area every time I wash a car (it's the last job before dumping the pail). And it's always dirty.

That's the first spot you see rusting on trucks especially - they have a wide dirt collection shelf right there.
 
The cheapest way is that spray on undercoating that is asphalt. It is canned tar, essentially.

Sticky enough that you could probably forgo most of the prep, gooey enough that it will never chip. It will also seal in rust and presumably moisture underneath. It would be much better than paint especially in that area.
 
Originally Posted By: Snagglefoot
I’m always amazed at how many trucks are out there with rusty fender wells. The remainder of the truck is usually just fine. While new trucks are coming out with plastic liners, what type of treatments seem to work to prevent the fender well rust on older models of trucks and cars. Thanks.


It depends on how much rust has already started. If it already got going a cutter and mig gun may be the only rustproofing.
There are some very good corrosion protection products but they are expensive and require special guns to apply but even they are only as good as the guy applying it.
 
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