Awe man... frame rot

[VernySanders]

Just when I finally decided to make my truck a full time dune toy and keep it enclosed for the winter I start to do extensive rust control on my frame. Complete wire wheel followed by Extremely strong laquer thinner then phosphoric acid. My POR-15 comes in the mail tomorrow and I finally decide to take a look at my frame next to the muffler. Notorious rot spot. I knew I had a little hole but thought "I'll get to it" well I got to it. Sadly not before it got to me.

The design flaw in these frames is insanely horrible. Severe lack of drainage in the center of the frame which is strange because it's a low spot as the front and rear are higher and then dip down as they converge into the middle of the frame. Then theres the fact that the muffler is located literally an inch or less from the frame itself emitting a constant heat. I know for a fact without a doubt the muffler is what caused my rot because the drivers side is also flooded with sand and debris but hardly any rust! I can still feel factory smooth finish paint on the inside on the drivers side!

I'm lucky I caught this in time. Even though I'd rather do a full frame swap I'm a few years out from that and by that time good luck with finding one. My rear control arm mount is entirely rotted on the weld on the inside and almost mint on the outside. Yet again the only difference being the Inside is constantly receiving heat from a hot muffler.

I fell in love with my truck and even though it's coming up on 20 years of age with 251,000 miles I'm never going to get rid of the thing. I will fix and repair as needed. New engines or transmissions etc. I'm only 23 years old. This thing has a long life ahead of it.

I'm personally going to be getting rid of the factory muffler and replacing it with something far more slim. Maybe catback maybe nothing but a straight pipe. I will also drill a few half inch holes in key locations underneath the frame to allow for proper drainage as currently theres no way in hell the little pin holes are doing their jobs.

Anyways rant over. Just a heads up to all you owners out there. Go ahead, do yourself a favor and look at your frame right next to your muffler. Especially if you live in the midwest like I do. I plan on tackling the rest of the frames interior with various methods and then completely overdoing it with the Eastwood internal frame coating after various other soak methods.

I refuse to lose my truck to rot. The only way I'll lose this bad boy is if someone steals it or it gets totaled in an accident. Otherwise bury me in it.

 

[dogtail]

Yikes, taking a salty beating. The muffler has nothing to do with it. Prevention is of utmost importance. I don't get rust.

 

[hamsandwiches]

Agreed, muffler has no effect. Heat is not what causes rust, its typically moisture inducing a higher oxygen concentration making it more likely to bond with the iron.

Unless you have an exhaust leak at/around the muffler, and oxygen remaining in the exhaust as water vapor was constantly blowing on the frame.

All rust is fixable IMO. My 98 was way worse than those pics. Over 20 lbs of rust. After spending two days with a grinder and welder and lots of plate steel after removing the gas tank I had it safe and solid again.

The reason people think these rigs rust more than other comparable vehicles is because they last so long.

 

[thennen]

Yikes, taking a salty beating. The muffler has nothing to do with it. Prevention is of utmost importance. I don't get rust.

Muffler absolutely DOES have a lot to do with it. Mine did the same thing, and when I had it estimated to be fixed, the highly-reputable frame shop had 4 or 5 third gens owned by employees. They explained that exhaust heat in the winter, along with exhaust gases that escape as the muffler ages, cause the frame to fail there first. Mine had a 2.5-foot hole in the frame next to the muffler but none on the other side. Dealer told me essentially the same thing.

 

[thennen]

Agreed, muffler has no effect. Heat is not what causes rust, its typically moisture inducing a higher oxygen concentration making it more likely to bond with the iron.

Unless you have an exhaust leak at/around the muffler, and oxygen remaining in the exhaust as water vapor was constantly blowing on the frame.

All rust is fixable IMO. My 98 was way worse than those pics. Over 20 lbs of rust. After spending two days with a grinder and welder and lots of plate steel after removing the gas tank I had it safe and solid again.

The reason people think these rigs rust more than other comparable vehicles is because they last so long.

Heat from the muffler in winter causes that part of the frame to stay moist longer in snowy, icy weather. In Ohio, at least, this is a thing.

 

[thennen]

Sadly had to abandon my 2001 due to rust a couple months ago. When I drove it the final 40 miles to the dealership to trade on a RAV4 for my wife, it was squirrelly and weaving on the highway due to at least one failed weld. I’m glad you have the energy and means to repair yours. Mine had NO mechanical problems at 265k when I got rid of it. That made it even more frustrating. Ohio road salt and flawed frame manufacture (Dana Corp?) combined to kill it. I’m happy for those in arid climates, where this isn’t a problem.

 

[hamsandwiches]

Not going to argue about the muffler stuff, but I had the same rust but more. It was on the other side, with little rust near the muffler.

 

[MaineRunna]

Sadly had to abandon my 2001 due to rust a couple months ago. When I drove it the final 40 miles to the dealership to trade on a RAV4 for my wife, it was squirrelly and weaving on the highway due to at least one failed weld. I’m glad you have the energy and means to repair yours. Mine had NO mechanical problems at 265k when I got rid of it. That made it even more frustrating. Ohio road salt and flawed frame manufacture (Dana Corp?) combined to kill it. I’m happy for those in arid climates, where this isn’t a problem.

All gen 3 4runners are built in Japan so it's a Japanese frame. It's not so much a flawed frame as it's just old. If this was a 70's Bronco, Scout, CJ, Toyota pickup or any boxed frame vehicle it would be rusted out in 4 years in the rust belt. The fact that these have held up so well is a testament to how awesome they are! VernySanders your frame is totally fixable. Take a holesaw and drill a few drain holes in the bottom of your frame after you get it fixed.

 

[dogtail]

Muffler absolutely DOES have a lot to do with it. Mine did the same thing, and when I had it estimated to be fixed, the highly-reputable frame shop had 4 or 5 third gens owned by employees. They explained that exhaust heat in the winter, along with exhaust gases that escape as the muffler ages, cause the frame to fail there first. Mine had a 2.5-foot hole in the frame next to the muffler but none on the other side. Dealer told me essentially the same thing.

You can blame it on the muffler heat, road surface at shoulder side holding more slush run off, or whatever. Even if Toyota designed these with straight pipes out the front fenders, they would still rot out. Its not just the frame that's taking a beating either. Rust damage is not exclusive to 3rd gen 4runners.
You can listen to the frame repair shops or dealers telling you theories on rust.....or you can do what people that keep their rigs from rusting out do.
Here's a pic of my muffler next to my frame with 363K that lived in the rust belt its whole life, original paint. The only thing I do is 1 hour per year of rustproofing, that's it.
Seriously its so super simple to prevent, its too bad more people don't know.

 

[thennen]

You can blame it on the muffler heat, road surface at shoulder side holding more slush run off, or whatever. Even if Toyota designed these with straight pipes out the front fenders, they would still rot out. Its not just the frame that's taking a beating either. Rust damage is not exclusive to 3rd gen 4runners.
You can listen to the frame repair shops or dealers telling you theories on rust.....or you can do what people that keep their rigs from rusting out do.
Here's a pic of my muffler next to my frame with 363K that lived in the rust belt its whole life, original paint. The only thing I do is 1 hour per year of rustproofing, that's it.
Seriously its so super simple to prevent, its too bad more people don't know.

Keep in mind that I bought my 2001 in 2005 and NEVER did anything to address frame rust. This is because I never knew frame rust was a thing until it was too late. So if you've been treating your frame on a regular basis, then you won't see what I've encountered. My previous 4Runner was a 1988. Never had to address rust with that vehicle.

So I get it - if I had done what you do, I would never have a problem. Since I didn't, my problem started next to the muffler. Physics explains why the muffler side goes first, and many others have experienced the same thing.

 

[Sarki]

The only thing I do is 1 hour per year of rustproofing, that's it.
Seriously its so super simple to prevent, its too bad more people don't know.

Please share with us the product you use and your application process.
I live in lower Hudson Valley where the roads are salted and would love to feel more comfortable driving my older Toyota trucks in the winter.
I’m all for a solid regiment of rustproofing.
Just need to know what to use and how to apply it.

 

[dogtail]

Keep in mind that I bought my 2001 in 2005 and NEVER did anything to address frame rust. This is because I never knew frame rust was a thing until it was too late. So if you've been treating your frame on a regular basis, then you won't see what I've encountered. My previous 4Runner was a 1988. Never had to address rust with that vehicle.

So I get it - if I had done what you do, I would never have a problem. Since I didn't, my problem started next to the muffler. Physics explains why the muffler side goes first, and many others have experienced the same thing.

Yeah I know what you're saying. You have to lose one to rust to know what happens, and that's what happened to me on another one. I also got a Taco buyback on frame damage. So I said no more, and just prevented it from happening. No matter the kind of vehicle you drive in the rust belt, salt will give it a beating over time. Some fair better than others, but all get some rust eventually. But but if coated with a barrier, you're protected. It has to be done properly and diligently. Its actually very easy I found.

 

[dogtail]

Please share with us the product you use and your application process.
I live in lower Hudson Valley where the roads are salted and would love to feel more comfortable driving my older Toyota trucks in the winter.
I’m all for a solid regiment of rustproofing.
Just need to know what to use and how to apply it.

Here's my write up. I've shared it many times on this forum. Follow these easy steps, don't deviate, and you are hard core protected.
SEASONAL RUST PROOFING using WD-40 only

 

[samc5mith]

That frame is done for

 

[Sarki]

Here's my write up. I've shared it many times on this forum. Follow these easy steps, don't deviate, and you are hard core protected.
SEASONAL RUST PROOFING using WD-40 only

That’s a great write up, thanks big time. Will definitely use this as a guide.
Planning on looking into Fluid Film as have heard good things about it and supposed to be a bit easier on the planet then WD.

 

[VernySanders]

All gen 3 4runners are built in Japan so it's a Japanese frame. It's not so much a flawed frame as it's just old. If this was a 70's Bronco, Scout, CJ, Toyota pickup or any boxed frame vehicle it would be rusted out in 4 years in the rust belt. The fact that these have held up so well is a testament to how awesome they are! VernySanders your frame is totally fixable. Take a holesaw and drill a few drain holes in the bottom of your frame after you get it fixed.

I'm going to for sure!! I never realized the questionable drainage these have and always being up at the sand dunes creates the need for some bigger holes. Thanks!

 

[VernySanders]

You can blame it on the muffler heat, road surface at shoulder side holding more slush run off, or whatever. Even if Toyota designed these with straight pipes out the front fenders, they would still rot out. Its not just the frame that's taking a beating either. Rust damage is not exclusive to 3rd gen 4runners.
You can listen to the frame repair shops or dealers telling you theories on rust.....or you can do what people that keep their rigs from rusting out do.
Here's a pic of my muffler next to my frame with 363K that lived in the rust belt its whole life, original paint. The only thing I do is 1 hour per year of rustproofing, that's it.
Seriously its so super simple to prevent, its too bad more people don't know.

sadly I've only owned my truck a year or it would also look like that. I'm in the middle of doing a full undercarriage resto. It's honestly not even bad mostly just the back. Wire wheel then xylene then phosphoric acid then POR-15 and Eastwood coating on the inside which I'm going to clean out with a chain attached to the end of a steel wire ran through PVC. Put it on a high powered drill and get as much of the shit out as possible then a good washing and spray it.

 

[VernySanders]

Got the frame rot completely cut out and patched. Also added a Borla XR1 muffler as well. Cant recommend this enough!! The Gibson catback honestly sounded like a ricer on the videos I saw and the flowmaster 40 series seems like it would be extremely loud and drone which this Borla does NOT do. Fortunately the only rot I had was this area and now it's taken care of so I will now continue restoring the rest of the undercarriage! I also dumped my exhaust in front of the rear axel instead of pointlessly running it back past the rear bumper. Turned out great! Deleted one of my cats already in the past and nodded the rear o2 sensor. Had 3 inch pipe from that so I continued with the 3inch into the muffler and out of it as well.

 

[sleepydad]

Got the frame rot completely cut out and patched. Also added a Borla XR1 muffler as well. Cant recommend this enough!! The Gibson catback honestly sounded like a ricer on the videos I saw and the flowmaster 40 series seems like it would be extremely loud and drone which this Borla does NOT do. Fortunately the only rot I had was this area and now it's taken care of so I will now continue restoring the rest of the undercarriage! I also dumped my exhaust in front of the rear axel instead of pointlessly running it back past the rear bumper. Turned out great! Deleted one of my cats already in the past and nodded the rear o2 sensor. Had 3 inch pipe from that so I continued with the 3inch into the muffler and out of it as well.

that is going to sound so cool when you go thru a couple feet of water, blub blub blub...

so you like that Borla, I will be looking here for my exhaust setup in a little bit. any chance you can post a video of it running? I will give you my free internet points.

 

[dogtail]

Hopefully where the exhaust blows out like that doesn't heat up your rear end and dif. I had my tail pipe break off and left it a couple weeks, it was blowing right at the rear end. It heated up the lube and took out my new pinion seal.