2003 LX470--how to attack undercarriage rust?
- Thread starter unkltrp
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GTV
SILVER Star
Depends on how bad it is, where you live, etc. Post pictures.
Lots of approaches and products to use. A lot depends on the component area that needs attention. Most urgent area is with the fuel system. Other areas can begin treatment while you take time to spin up on an approach and tools.
FamilyCamper
SILVER Star
Make sure fuel lines and brake lines are replaced as needed. I have had 3 brake lines form small rust holes sadly and my rust really isn't too bad. The way I treated was a ton of grinding with a thick wire wheel and then power wash and blow out the inside of the frame. Eastwood rust encapsulator paint/spray paint 2 coats and then a coat maybe 2 in spots of chassis black. 4 cans of Eastwood internal frame coating for the inside of the frame or hard to reach spots bc it is very viscous and seems into cracks and crevices. Very messy job and would be great to do on a lift and not under the truck like I did. Probably put in 25-30 hours and it's held up solid and no rust through or flaking after 2 years. Lots of wheeling and mud in between.
As mentioned, we need pics. Sometimes the answer is grinding, painting, protecting and other times, protection (like wool wax or fluid film etc) is all you need. It’s almost never worth it to put any money into fixing it as it will never stop if it’s already got its hold and is eating metal vs just a bit of surface rust. You can do what the poster above did, it’s more labor than money. Easier to get a different truck down the road if you wind up loving the platform and can’t fix the rust. I first bought a 100 series that was rusty, a few years later I bought a 100 series that was rust free.…. Still have both but would only invest dollars into one of them.
thorough approach:
scrape / grind / sand rust until you reach bare metal
apply rust converter, quality primer and topcoat
wait a few months then coat with woolwax / fluidfilm / cosmoline
minimalist approach:
knock off as much rust flakes as you can
spray down with fluidfilm
scrape / grind / sand rust until you reach bare metal
apply rust converter, quality primer and topcoat
wait a few months then coat with woolwax / fluidfilm / cosmoline
minimalist approach:
knock off as much rust flakes as you can
spray down with fluidfilm
Depending on the work you need to do, these mini induction heaters work magic on removing rusty bolts. Safer to use than a torch.
Has the 100 lived for 20 plus years in New York?
No offense to previous posters, but I DO NOT recommend anything that 'encapsulates' rust.
This is an extreme example, but it shows what can happen when you encapsulate rust. The salt and water are still in there, eating away.
I highly recommend Fluid Film or Woolwax, with Woolwax being better but more expensive. These are lanolin based waxy oils. They are non-toxic and safe on all rubber/plastic components.
In 2020 I purchased a 2003 GMC 2500 with some pretty severe frame rust. I needle scaled the whole frame and took pounds and pounds of rust off, but I never came close to getting it all. It was NASTY.
What worked was applying Fluid Film over the next few years. By the second year, almost all the rust had fallen off on its own and the frame was clean black metal again. Also removing any kind of hardware got much easier, as the wax had acted like a penetrating oil.
Sadly I had to sell the truck... but was to fund my land cruiser, so it was a net positive haha.
These pics are right after a fresh coat of Woolwax. There's still some visible rust, but it definitely doesn't look like a 20+ year old Maine truck anymore.
This is an extreme example, but it shows what can happen when you encapsulate rust. The salt and water are still in there, eating away.
I highly recommend Fluid Film or Woolwax, with Woolwax being better but more expensive. These are lanolin based waxy oils. They are non-toxic and safe on all rubber/plastic components.
In 2020 I purchased a 2003 GMC 2500 with some pretty severe frame rust. I needle scaled the whole frame and took pounds and pounds of rust off, but I never came close to getting it all. It was NASTY.
What worked was applying Fluid Film over the next few years. By the second year, almost all the rust had fallen off on its own and the frame was clean black metal again. Also removing any kind of hardware got much easier, as the wax had acted like a penetrating oil.
Sadly I had to sell the truck... but was to fund my land cruiser, so it was a net positive haha.
These pics are right after a fresh coat of Woolwax. There's still some visible rust, but it definitely doesn't look like a 20+ year old Maine truck anymore.
For anything underbody, I use a pressure washer blasting kit. Remove all of the rust then treat, and use proper coating. Covering rust just creates a bigger problem. I use Fluid Film to as a temporary measure and preventative until I can do it right.
What do you consider doing it "right"?
Sounds like any kind of paint is essentially encapsulating rust which is a no-no. Fluidfilm/woolwax is the only thing that people seem to believe in anymore.
These cars came out of the factory with what? Just paint? Why does it rust worse than a honda? Is there a consensus? Is it the same issue as the steel recall that was called out on the sequoias and tundras? Part of the same batch, or no?
I've used Woolwax (outside frame) Fluid Film (inside frame) on my GX470 for 3 years now. I'm in MO where we have some salt on the roads and older vehicles commonly rust. It's not NY bad but also pretty far from Texas-good.
2021, after pressure wash and pre-application of Woolwax/Fluid Film.
2024, after pressure washing and pre-2nd application of Woolwax/Fluid Film.
2024, post application.
Absolutely zero progression of any of the rust over 3 years. There was quite a bit of old coating still left on the frame. It mixed very nicely with dirt road dust to foam a fairly resilient coating. A lot of it didn't come off with the pressure washing. The only places I touched up over that 3 years was inside the rear wheel wells and the bottom of the rock sliders. The rig gets driven in all weather, goes thru mudholes, creek crossings, etc.
So....yes the WW/FF really does work and works quite well, and is easy to DIY. It's also totally nontoxic and acts like lotion if you get it on you.
2021, after pressure wash and pre-application of Woolwax/Fluid Film.
2024, after pressure washing and pre-2nd application of Woolwax/Fluid Film.
2024, post application.
Absolutely zero progression of any of the rust over 3 years. There was quite a bit of old coating still left on the frame. It mixed very nicely with dirt road dust to foam a fairly resilient coating. A lot of it didn't come off with the pressure washing. The only places I touched up over that 3 years was inside the rear wheel wells and the bottom of the rock sliders. The rig gets driven in all weather, goes thru mudholes, creek crossings, etc.
So....yes the WW/FF really does work and works quite well, and is easy to DIY. It's also totally nontoxic and acts like lotion if you get it on you.
