Here are some additional photos of the frame from the trailer hitch down the passenger side frame.

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Here are the photos from the front of the vehicle towards the back along the driver side.

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To me it looks solid enough, that if you rust-treat it with a grease-base anti-rust right after buying, you could go long with that truck without worrying. Seems like mostly surface rust that had the time to work deeper. But it is not rotten.

Exception being that I would have a solid look a the part that attaches the frame to the rear trailing arm (the kind of triangle). Seems like the worse area in your picture, it's a weak area that rusts easily, really have a look if it is still solid enough. If it is, rust treat that thing in and out with grease/oil based every year. Also have a look at the underside of the rockers extremities, seems like you could get through with a screwdriver.

Agree with above. Its probably fine but it needs attention, even if just a thorough coating of oil based rust inhibitor everywhere, applied yearly. Also you'll need to deal with the diff cover.

Thanks for the replies. The diff cover didn't have any pinholes, it actually had a a crack in it from a rock hitting it or something. I couldn't afford to get a new cover so I tried to remove all the rust and scrape the whole thing down to bare metal then applied 3 layers or so of JB-Weld and topped it off with some rust reformer. Didn't see any metal chipping when I drained the fluid and isn't leaking so I think I'm good on that

Jb weld will only hold a few years. It's not really a good thing to use on frame or diff covers it will not last.


The underside needs coated with rust inhibiting coating of some sort to slow the rust down. Super clean the inside the frame and really coat it too as these frames rust from the inside out.

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I wasn't able to get around to the rust portion as I started grad school and moved to Michigan. I have been washing the the car and undercarriage pretty often as I have invested in a car wash pass. After this semester is over (May of 2022) I will be doing quite a few things to the 4Runner. First of which will be the rust, and may possible make a thread for those who are curious, as I feel my plan is pretty comprehensive. I don't really have the time, knowledge or tools/lift needed for a frame swap so I think cleaning up the frame is my best and cheapest option.

My current less detailed plan is to first make some cheap sturdy stands to place some jack stands on. Then sand blast the frame, and try to get the inside of the frame, with a pressure washer sand blaster attachment (~ $32 on Amazon) and then pressure wash it to get rid of all the sand so it doesn't get trapped. After it dries ill go around with a wire wheel (~$ 12 on Amazon), needle scaler (~$28 from harbor freight) and wire brush to get rid as much as I can. Then, wash it off again and let it dry before I coat the inside of the frame with either KBS's internal frame coating(~$35 a bottle for 150 sq ft) or EastWoods rust encapsulator (~$28 a bottle for 10 sq ft.). I then will begin using MasterCoats Rust Kit (~$103) which includes a rust reformer/metal prep, rust sealer, top coat and special thinner (which I plan on doing with a ~14 spray gun from Amazon). Ive heard several people recommend POR-15 or KBS, but I think this will work better as its industrial grade (what they use on bridges for ~15-20 years) in New England. Plus just the top coat alone (ag111) has held up better than other products in an oxygenated brine bath for a few months. Once Im don't with that I plan on adding another top coat/ enamel product like POR-15 Top coat or raptor liner (~$48 for two cans on Amazon). Finally, I plan on spraying the frame, doors and everything I can with wool wax black, using their spray gun(~100 dollars for their gun and a quart of wool wax black on Amazon). After everything, including tax, it comes out to around $450 for everything.

What do y'all think about a plan of attack like that? Its going to be a lot of work, but I plan on having it till she hits at least 300K (currently at 169K) and want something that I'm only going to have to do once, except for reapplying something like wool wax or fluid film.

I will probably wait on the the diff cover, but may look for a whole new rear end. Seems like way more of a hassle than its worth since its not a bolt on and you actually have to cut it off then weld a new one back on without getting any metal into the pumpkin area near the gears. Plus my grandpa and I have had pretty good luck with JB-Weld thus far. He's used it on an engine block on his square body chevy and I believe it's still holding up fine ten years later. Granted he doesn't daily it like I do my vehicle, but still drives it a decent amount.

Well all my jb weld cracked and let my diff cover seap again in less then 2 years. I live in the same environment you are currently in as I in southwestern PA...

The Eastwood frame coating didn't work for me either. Maybe it's just me, I used it in an arch I sprayed it into rust when I went back in to fully fix it a year later it was rusting..


I basically repair 3rd gen 4 runner frames as I hobby and even rebuild them from rot damage.

You other methods sound very good. I just know from experience that it is extremely difficult to clean out the frames if they are full of dirt or debres or rust. I even do all my frame repairs [plating ]on the inside of the frames.

In the rust belt, I basically try to remove the frame holes to keep the salt water etc out and when repaired I paint for an indicator then coat with a rust inhibitor. My build thread is full of actual frame repairs in these frames.


Have a good semester as I am looking forward to seeing you build/ repair thread when school is out.

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Thanks for the advice, I'm looking forward to doing this! Do you have any more on how you do/would try and clean out the inside of the frame?

Your plan sounds like a crap ton of work. You can still save that frame for sure. I would get under it and use a screwdriver and scrape off all the rust bubbles. Go on Amazon and get a 12 pack of fluid film that comes with the 360 degree spray attachment to get inside the frame. DRENCH that frame inside and out using all 12 cans. That’s what I did when we got our 4 runner. Just spray every year and that will keep the rust from progressing. Painting only works if you remove ALL the rust, because if you don’t it will grow back under the paint. Fluid film stops rust by keeping oxygen and moisture out of the picture. They sell it in black to make it look good. Good luck!

Yea, its going to be a lot to do. I was thinking that the sandblasting power washer attachment will get a lot off if I take my time with it so I can hopefully get most of it off. Im hoping MasterCoat's products work well, I've been in contact with them and asked about their products and their tests and everything seems to make sense on what they are stating their products are capable of. But just to be safe coating everything with the wool wax (pretty much the same as fluid film just plan on using it because they have a pretty good deal on their application gun and a quart of their product as compared to fluid film) will be an extra line of defense.