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So, it depends.

Are you hoping to use this forever/ indefinitely or for a few years?

Where do you live and is there ongoing exposure to salt?

How much time/ budget do you have

Do you care how it looks, or just want to make sure it doesnt rust through and become unsafe to drive?

The other areas I would check are the radiator support under the front of the vehicle. The frame near the passenger front wheel well/ door - The AC drain is here right on to the frame for some reason and can be a cause of rust. and the rear cross member under the bumper cover. Those will be the most likely spots to rust significantly

You could do nothing and just watch it regularly. If your state has state inspections, someone will have to get under once a year. Otherwise, anytime you have to bring it in, theyll generally do a quick safety check before putting it on a lift

You could try to remove all the flaking/ rusting metal you can. Scrape it, needle it, sand blast it and then use a rust converter and paint it

You could look into professional shops for rust mitigation/ repair

Hi all,

Sorry to resurrect an old thread but this seemed like as good a place as any rather than waiting to start a new one.

New member here, I have an 06 4R Sport V6 that's coming up on 180k miles. I've only recently started doing more of my own maintenance on it, and as such am getting under it for a good look for the first time. My concern, probably unsurprisingly, is rust. I've only done a surface-level look so far, and plan on getting under it again this weekend to look more closely. There's definitely a good bit of surface rust, but also a couple of areas that are more concerning to me. Forgive me for any incorrect terminology wrt the 4R and its components, but this is where the front suspension connects to the subframe (pics attached).

I'm interested in feedback on how bad this is and what remediation makes sense. I'm at a point where I need to make a decision on how to move forward given the mileage and other work I know the truck needs in the not-too-distant future (strut replacement being the primary one). I've seen other posts and videos about wire brushing/treating everything under there, but if this is going to require more extensive work, or it's not worth it at all, I'd rather figure it out before getting started on all that. I'm happy to take more pics this weekend but at least wanted to get some initial thoughts.

Thanks!

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That rust is pretty mild. I dont think your frame is gonna rust out anytime soon. You can certainly go ahead and wire wheel, rust convert, but may be a tough area to get it all

good luck

That doesn't look bad, just the coating Toyota applied chipping off. Scrape it off and see how it looks after that. The areas you need to watch are the bottom flat areas of the frame near the bottom of the axle arches, the front tow point areas and the frame behind the bumper cover.

Thanks to both of you, appreciate the clarity there. I hadn't thought about the coating flaking off, but yeah, that does seem likely. I'll get a better idea this weekend of what the trouble areas look like and plan from there. I don't know that we're looking to keep this thing through 300k or anything but I definitely want to head off potential showstoppers before they get to that point.

+1 to wire wheeling and poking with a screwdriver to see how deep it goes. From pics it looks like just surface rust and can easily cleaned up. I used the Eastwood rust converter and chassis paint on mine and it worked great and is holding up fine in NYC after 5 years although I also woolwax every other year.

One tip is also to drop the skid pans in the front, I just did a CV job and found some rust starting there on the arms next to the diff that needed wire wheeling and paint as it gets blasted by water and salt.

Its not a super fun job but highly satisfying and worth taking time over as a good job will last years. I did my whole underbody in 1 weekend when I got the car 5 years ago including the inside of the frame rails with Eastwood internal frame paint and its still looks perfect with some minor touch ups in the spring.

Ok so I did a little further looking this morning, and there were two areas that look like actual concerns. First, as mentioned, was behind the rear bumper. The are two holes on the driver's side corner, and the passenger corner looks a little rough too. There is a good amount of surface rust at least running the length of that section.

Second is right next to the cats. This looks like it's getting a little deep as well.

Thoughts?

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Yes, I think heat from the exhaust system can contribute to frame rust so locations next to CAT & muffler are susceptible. Common problem with 3rd & 4th gen T4R's in the snowbelt. Looks like you have frame rail perforations that should be addressed but not necessarily the end of the world. Plate can be welded in at that point to strengthen the rail and, depending on location, there are ready made fabricated patches like this....
All SafeTCap(R) Frame Repair Kits for 03-09 4-Runner - autorust.com
Need to find a competent welder and may want to start with someone who does frame restoration. After fixing that, I would apply a product like Woolwax over the entire frame to slow down future corrosion.

Ouch, yeah those are the areas that are at issue. Salty sand seems to sit in some areas so they rust from the inside out. Sadly, once all the rust is removed those holes will be huge. You're going to have to decide what you are willing to put into it for repairs, if that's even possible at this point and know that it may only be good for a few years at best. The Safe-t-caps mentioned are a good repair but you will end up with more holes elsewhere at some point.

BTW, having someone repair that will cost into the thousands, that's assuming you'll find someone to take it on. Sorry to say, but those pictures put that 4runner into the parts car range for most people.

Yikes, I can't say I expected the words "parts car" to come out of this conversation. I guess without at least having someone local look at it it's hard to know what's worthwhile, but my biggest concern at this point is at what point is the car actually unsafe? I'm trying to figure out how we can best determine what we can still get out of it, and how much might be worth putting into it. If it's already past the point of reasonable repair, how much longer is feasible for it to be drivable? I was just about to do a 180k service on it, but maybe I should hold off on even that until we get a better sense of the rust issue.

Here in NH, that would have failed inspection last year. Really hard to tell by pictures if safe or not. Best bet is to have someone look at it who does rust repair. The plus side is these frames are robust unlike some frames. Keep us posted.

I battled frame rust on my 3rd gen for 6-7 years before I sold it for salvage - welded on it three times. Mike is right that eventually your frame will succumb and that it is not inexpensive but depending on the location and severity of the rust, you could still get a number of years out of it. You really need to get under there with a welding hammer and/or screwdriver and knock that loose rust away to see the scale of the problem. Then check out those SafeTCaps and see if the available options would address your frame rust locations and go to a qualified local welder to see if they would take on the job. You could also check out that SafeTCap website list of installers - there might be one in your area. Alternatively, you could go to a frame shop and have them give you an estimate. Although most of these are classic car focused (and expensive), look for one that is more focused on collision work and, if possible, experience with T4R/Tacoma frames.

Thanks guys, appreciate the advice. There are several shops on the STC site that aren't too far from me. One shows some pretty nice welding work (to my amateur eye) installing this stuff on a Tacoma frame. I'll start there and report back what I find out.

Again, much appreciated.

I've been on that site a few times and never noticed they had recommended shops on their. That good to know.