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  1. #1
    Join Date
    Sep 2012
    Jacksonville, North Carolina

    Default Undercarriage rust. Ideas?

    Hi, I have a 2003 Chevy Silverado 1500 Z71. There is surface rust all over the undercarriage. I would like to keep this vehicle for a while so I wanted to do something to prevent the rust from spreading or getting worse. Also, it looks bad when you look underneath the truck. I have heard of people sand blasting it then applying rhino lining. Any better ideas?

    I like the new gas prices, don't you?

  2. #2


    you can wire brush it off and get some rust stop paint. or the bed liner in a can spray and DIY it.


    2011 GMC Sierra SLE 5.3 Z71 4X4 Stealth Gray Metallic / 2004 Chevy Impala LS 3.8 Cappuccino

    Tow mirrors - Diablew Tuned - Flowmaster Regular 40 - Ready Lift 2.5' lift - BFG LT A/T K/Os - Carr Light Wing - TruckLite LED lights - Optima Red Top - 50% Front Window Tint - Line-X bedliner - Airaid MIT - Tekonsha P2 - ARS Billet Grill - Fia custom fit seat covers

  3. #3


    I will spray it with rust converter then Por 15.
    2011 Chevy Silverado LT 4WD 30k miles
    2001 Suburban 2WD, 5.3, V8 185k miles
    1993 964
    1996 318TI

  4. #4


    Scrape off old undercoating (surprising how much rust is under a small wound).
    Spray with degreaser & wire brush to break up, Scrub with dish washing detergent & warm water, rinse let dry.
    Spray on Must For Rust (follow directions), scrub off what doesn't react with rust.
    Spray on two coats of Benjamin Moore DTM Alkyd Low Luster Black P25-80 (Direct To Metal), or
    Spray on Rustoleum Cold Galvanizing (97% Zinc) followed by Rusty Metal Primer & two coats of
    paint of your choice (I use the P25-80), then
    Spray on two (or more) coats of Flex Seal rubberized coating, at least in areas that get hit by wheel-thrown
    debris, and the front bottom frame rails that plow through snow & ice up here in the North.
    Spray Waxoyl inside the frame rails, rocker panels, & any of the rust out spots typical of your truck model.
    Recipes for homemade waxyoil can be found online;
    Fluid Film is an alternative. Be
    sure to keep flammable coatings away from manifolds, headers, exhaust system, heat shields, etc.
    It's a messy job. Dedicate lots of old expendable clothing & rags to this job (beware combustion of oily rags).
    Big sheets of cardboard are invaluable, change them as they get too gross to work on.
    Limit your skin contact with solvents, apply common sense, read all instructions, and at the end of about 40
    hours your truck will look brand new underneath like my 2008 does.
    2008 Silverado Reg. Cab Short Bed 5.3 4-Spd. Z71 4WD Plow & Tow Pkgs. 25U Dark Ming Blue

  5. #5


    Are you 100% sure it is all rust? Some of it could be iron deposits and I have gotten rid of that with Iron X and some scrubbing.

  6. #6


    Here in the North it's a bit harsher. Iron isn't being deposited, it's leaving as fast as it can. I just talked to a guy with a 2005 truck. He has to have a plate welded into his frame to repair a rusted out area. Four or more months of salt slush being flung up takes a severe toll (it's like an extra tax for living up here.). It's also why I added the factory "wheel house" liners to the back. I bought the truck four years old and was horrified at the job ahead of me when I dropped the spare tire. It needed lots of chipping away flaking rust up there. CaptainCal565 isn't in the rust belt, but he's not far from salt water and salt air causes rust also. If he's not too concerned with the bottom of the truck being a uniform black he could spray with rust converter and then fluid film.

  7. #7


    i would sand a little down and use a rust neutralizer and i would use either rhino liner or a really thin undercoating. you can get pretty much any color nowadays
    99 chevy 1500 silverado 4.8 vortec True 2.5' dual exhaust with 3' Silver vein tips and vx muffler, 2005 tail light swap, mb tko 16" matte black rims Upcoming mods:HID headlights, 2" leveling kit

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