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Thread: Rust

  1. #1
    Join Date
    Feb 2000

    Post Rust

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    Rust... Every year, millions of vehicles suffer many more millions of dollars in damage due to rust. As awful as the cosmetic damage is, rust can even make your vehicle unsafe to drive and you may not even be aware of it. I don't know of a single instance where someone dismantled their truck, sandblasted-stripped-repainted-recoated the metal parts and then reassembled everything to correct the damage caused by rust - just not worth it. What we'll do here is show you how to easily and inexpensively treat this rust problem.

    I owned this '55 Chevy back in the early 1970s. It had spent most of its life somewhere in Oregon before I owned it. Being near to the coast, the bottom edge of both doors had rusted out. I replaced both doors soon after I bought it, but there were no other rusted-through areas on the body. It was pretty solid otherwise. However, I was concerned about the quarter panels and the inside areas below the rear roll-up windows. Not having the time, money or the inclination to do a full restoration, I removed the interior trim panels below the rear side windows and squirted a little motor oil into the creases and tight spaces inside the body that were likely to develop rust. Later, in the 1980s, I did the same thing for a 1982 GMC 6.2L diesel pickup I owned at that time. These trucks could develop a rust-through problem in the bottom edge of the doors and in the cab corners. Neither the '55 nor the '82 GMC had another rust problem in the sheet metal while I owned them. The motor oil, as I discovered, will wick into the tightest of spaces, and will continue to prevent rust for years.

    The lead-in photo shows you what the rear differential and axle looks like in a 16-year-old truck that had been driven through 15 winters where road de-icer had been used on the highways. The appearance of rust is so disappointing to an automotive enthusiast. The above photo shows what the application looks like just a few minutes after having been lightly sprayed with a motor oil/solvent solution. The shiny appearance quickly goes away as the solution gases off and acquires a light coating of road dust.

    This photo shows that the oil spray had turned the frame rail and leaf springs flat black not long after having been treated. This frame rail had significant areas of ugly surface rust just prior to being treated.

    This image is of a 2005 GMC 2500HD LLY Duramax from Canada that had been exposed to road de-icer every winter since new. The arrow in this image points to a fuel line. You can also see that the front driveshaft should be replaced to avoid a structural failure. Proactively treating these areas once a year, like that described here, would prevent the damage from occurring.

    If you're an automotive enthusiast and live in the northern tier of America you know how awful road de-icer can be - and not just for your truck. Magnesium Chloride is also an environmental hazard. This photo shows a large Ponderosa Pine near where I live that was killed by MC. Snow slush saturated with magnesium chloride was thrown up by a snow plow onto this Pine during the prior winter, which killed this and dozens of other Pine trees that were apparently located too near this Montana highway.

    The motor oil I use for rust treatment here at is the blackest used diesel crankcase oil I could find. The blacker the better. I saved a gallon of used oil a while back for just this purpose. Most any spray bottle will work, such as an old Windex or Armor All spray bottle, but a spray bottle with a selectable spray pattern is best. Use a solvent to thin the motor oil so the solution will spritz. I've always used diesel fuel as the solvent, but a non-flammable solvent might be an alternative - perhaps like that used for an automotive parts washing system.

    While spraying, I do my best to avoid coating any rubber/neoprene part or the disc brake rotors and calipers with an oily solution. I have seen 6.5L diesel motor mounts and rubber isolated serpentine crank pulleys that were damaged (softened) by motor oil. Spray just enough to lightly wet the rusty steel surface you're concerned about. A drip indicates you're using too much. Use a little common sense. Wear gloves and safety glasses. The solution mentioned here will stop brake line rust wherever it's applied. Depending on conditions and location, the oily spray will provide rust protection for up to a year or longer. You may need to re-coat some areas every year or two - a small price to pay to keep rust from ruining your truck or making it unsafe to drive.

    Is this safe? I've heard many stories through the years of trucks developing fuel and/or ATF/oil leaks that wound up saturating the underneath of the truck. Even I had an automatic transmission cooler line fail once just ahead of the engine on the passenger side (exhaust side) of my Lil Red Duramax conversion truck, which caused ATF to coat the under-surface of the truck front to rear. Other than a mess to clean up, there was no other concern.

    Additionally, one summer more than 20 years ago I was called in to a local garage to look at a diesel Suburban that had developed a fuel leak on the engine, a big leak. The Suburban had been driven more than 120 miles on the Interstate with that fuel leak. The leaking fuel had stripped the undercoating off the underside of the vehicle from the engine compartment to the rear axle, and the fuel had been dripping onto the exhaust system the whole way. There was no fire.

    Not to put too fine a point on this issue, but most LB7 Duramax owners have likely read about what happens when an injector fuel return line leak occurs beneath the valve covers of the LB7 (first gen Duramax) engine... It results in a fuel leak into the crankcase, which eventually overfills the oil level to a point of spewing out the crankcase vent system. This coats the entire underneath of the truck and any trailer you're towing with a diesel fuel and oil mixture. No fires have been reported here in as a result of a fuel return line leak beneath the valve covers. That being said, always use your own judgment about whether you believe what is being suggested here to help prevent rust is safe for your situation.

    As was mentioned earlier in this article, here at I've been treating rust using this method for decades, and I've not found a better, easier, more convenient or less expensive way to prevent rust from ruining a vehicle or making it unsafe to drive. If there's another solution to this rust problem - one that works as well and is as easy/cheap, let me know and I'll update this page with your suggestions. In the meantime, try what I'm suggesting here on a small rusty area on your truck that is well out of view. I find it amazing how well this works, but try it, then give it a week, and let us here in forums know what you think.

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    Related: Article - Room For Improvement
    Last edited by More Power; 09-09-2022 at 09:28.

  2. #2
    Join Date
    Feb 2000

    Post More Rust...

    I replaced the factory exhaust system in my 2001 GMC back in 2007 with an aftermarket 4" performance-oriented exhaust system. Most of this system is made using stainless-steel, which remains in fine shape despite the intervening years of winter road de-icer. However, there was one exhaust system hanger not made from stainless that wasn't quite up to the challenge.

    The angled rod shown here (attached to the rusty clamp) was made from stainless-steel. The rod had accumulated a thin layer of crud, but it was not corroded or had deteriorated in any other way. This angled rod was removed from the rusty clamp using a cut-off wheel a few minutes after this photo was taken, then cleaned and welded onto the new clamp shown at the top of this photo. The new clamp is made from stainless and galvanized steel. By the way, this particular clamp is used at the rear of the muffler. Surprisingly, this was the only badly rusted exhaust system clamp. All of the other clamps were OK, apparently made from either stainless or galvanized steel.

    It's all good now! No worries. I'm not mentioning the brand of exhaust system for a couple of reasons... 1- This system has been on the truck for 15 years. 2- Products change over time. So, if you're in the market for a performance exhaust system, ask about its resistance to the highly corrosive nature of road de-icer. Do they use stainless-steel or other corrosion-resistant materials?

    While under the truck, I re-applied a treatment of the motor oil solution discussed earlier to the frame and chassis components that had begun to rust since the last treatment. I do this every couple of years. Not doing it would cause the under surfaces to look pretty much like the above muffler clamp. I find the oil treatment amazing in how well it protects the rust-able parts of the frame, suspension components, inside surface of the bumpers, brake lines, brackets, drive shafts and any sheet-metal areas that had been chipped by gravel.

    I'm also beginning a brake system project for this 2001 GMC.... because of rust. I have a new set of NAPA Premium brake rotors and their PROFORMER brake pads ready to go on. The NAPA rotors are coated in all areas other than where the pads come into contact. The original rotors had rusted so badly that the brake pads had lost contact with large areas of the rotors. This left large areas of rust on the braking surfaces of the rotors, which eventually made contact with the pads as they wore. When that happened, it quickly wore through the pad material till there was metal on metal. Mind you, I had installed new tires on this truck just a year and 7,000 miles ago. The tire center inspected the brakes at that time and wrote on the paperwork that the pads were at 50%. The rear inner pads were the ones (both R/L sides) that failed due to rust. However, all four rotors are a rusty mess, so I'm replacing both front and rear. I'll have a complete R&R article available on the web site once the project has been completed.

    Last edited by More Power; 04-19-2023 at 10:14.

  3. #3
    Join Date
    Feb 2000


    I'm involved in another rear brake replacement/repair project because of rust. This time in my wife's Chevy Malibu. Just like my 2500HD, the rear brake pads began losing contact with the rotor in large patches. The winter road de-icer deposits a film on the brake pads, causing a loss in contact with portions of the rotor. The progression first causes a loss of braking effectiveness, then over time significant wear of the brake pads as that small contact patch wears away, exposing the pads to a badly rusted/pitted rotor. This process of rusting brake components produces a big safety problem. They need to either make parts that don't rust, or use a de-icer that doesn't cause rust.

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