My 4runner is starting to show some signs of rust in some spots and I was hoping someone with more experience could shed some light on my best options for treating it. And if the rust is going to be too much of a problem to fix. I'd like to keep my 4Runner going at least another 100k miles.
Rust problems
- Thread starter twr412
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MN4runnerman
Senior Member
Pics speak a thousand words
You beat me to it. I was uploading lol
LookAtThatDog
New member
It doesn't look too bad at all. You could grind the frame down and undercoat it with POR15 or something of the like. At a minimum, take it to the self-wash a couple times a month in the winter.
Actually that has been my project the last week or so. I am using some phosphoric acid to react with some of the rust so I don't have to grind it down. I plan on using POR15 with a top coat of black. But I wanted some outside input before I did anything. I generally try and wash the undercarriage after it snows and the salt clears. Thats probably the only reason it isn't worse. As you can see by one of the pictures, my 4runner is no stranger to snow.
MN4runnerman
Senior Member
Ah gotcha. Like the poster said above. It doesn't look bad your actual frame looks good but your cross members and lower control arm mounts are looking iffy. I'd check those out and make sure they are good before coating the frame with anything. Your gas tank skid looks crappy too, mine looked like that and I bought a separate one and fixed it then swapped it.
RPS99SHO
New member
I recently PORed mine. My frame looked almost as bad as yours.
http://www.toyota-4runner.org/3rd-gen-t4rs/215743-i-hope-i-bought-my-frame-few-more-years.html
I also sprayed Fluid Film inside the frame.
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Actually all my skids are crap. My front skid rusted a 3 inch hole through it. Gonna buy some new front skids and try to salvage to the gas tank skid. Maybe but one from a junk yard if I can find it.
MN4runnerman
Senior Member
I paid $10 for a gas tank skid that was in better condition than the one I had on the vehicle from a salvage yard. If you wanna splurge you could get some aluminum skids from one of these companies that are vendors here. I might do that eventually.
shahsmerdis
New member
Short version, rust is boarderline, but you caught it mine looks a bit worse, and is still structurally sound. , check neary the frame near the muffler also check the lower control mount around the gas tank. (further where the area of the frame where the gas tank meets the frame. If those dont't have any holes chances are you are okay. Also check your brake and fluid lines. get a machine and wire wheel attachment, then degrease the entire underside of your car. Links to come when I am home. Also change your rear diff breather if the 2WD has one.
POR15, is huge time commitment and is still isnt going to give you 100% coverage. I like fluid film or waxy coatings as its the most practical.
the most important point is to find the key areas in which frame usually fails, and spray the s*** out of it asap. another key thing a lot of people here don't say is your brake lines and fluid lines. you want to at least spray fluid film on those to stop the rust from getting worse.
short unedited version, longer post when I am home.
POR15, is huge time commitment and is still isnt going to give you 100% coverage. I like fluid film or waxy coatings as its the most practical.
the most important point is to find the key areas in which frame usually fails, and spray the s*** out of it asap. another key thing a lot of people here don't say is your brake lines and fluid lines. you want to at least spray fluid film on those to stop the rust from getting worse.
short unedited version, longer post when I am home.
I think I am gonna splurge for the front skids from savage. But you can't see the gas tank skid unless you are under the car, so that one will come from a junk yard if I can't salvage the one I have. I'll see what some phosphoric acid and an angle grinder can do to it.
I'm doing this pretty soon too. What I got was recommended by a local shop that does this kind of service all the time.
Klean-Strip 1 gal. Phosphoric Prep and Etch-GKPA30220 - The Home Depot
Same stuff as the more expensive brands marketed for car frame use.
I'm planning on using a wire brush on a drill to knock the worst of the rust off, then apply that stuff. Then paint it with this.
Rust-Oleum Stops Rust 1 qt. Flat Black Protective Enamel Paint-7776502 - The Home Depot
Klean-Strip 1 gal. Phosphoric Prep and Etch-GKPA30220 - The Home Depot
Same stuff as the more expensive brands marketed for car frame use.
I'm planning on using a wire brush on a drill to knock the worst of the rust off, then apply that stuff. Then paint it with this.
Rust-Oleum Stops Rust 1 qt. Flat Black Protective Enamel Paint-7776502 - The Home Depot
shahsmerdis
New member
holy cow that looks good. hope it holds up. how long did it take you
MN4runnerman
Senior Member
I feel ya that's exactly what I'm planning on doing.
RPS99SHO
New member
6 hours from on the ramps to off the ramps. The jury is still out on how long the POR will hold. Even if it does flake off in some places that were not as well-prepped as others, it is still a ton better than having the whole frame exposed and rusting to death.
Frame near the muffler surprisingly isn't all that bad. And all brake and fluid lines were inspected and are good. Most of the worst parts of the rust are on and near the rear diff and up under the spare tire. Oh, and the lower control arms. Would you suggest removing the lower control arms to derust? My 4runner is my winter car so I can afford to have it off the road for a week or two.
Yup, that is the exact stuff that I have. I forget how I found out about it but its the cheapest phosphoric acid I can find.
shahsmerdis
New member
Yes, the rear end of mine got the worst of it too.
No don't take anything off. Waste of time if you ask me. the control arms are easy enough to put corroseal on. its a rust converter 20-30 bucks a gal at home depot. (or any rust converter) Simply mechanically remove the rust as best you can, (Machine only) degrease it, ensure it is fully dry then apply your chemicals.
if you are going to brush anything on, I read the best method is get one of those 1 inch brushes, and cut the bristles in half, that way you have a lot of even control of your product without applying too much.
these are two videos that should help you see what kind of products are out there. and in generally every company has some sort of equivalent of these products, not saying you need to use east wood the just summarize it well.
https://www.youtube.com/watch?v=OvgkQK0g-n8
https://www.youtube.com/watch?v=ola_UhwJscU
silver4est
New member
How long do you let that phosphoric prep stay on the frame befor you clean it off? Do you hose it off? Spray it on or brush it on?