What did you do for exhaust replacement?

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tedwardd

tedwardd

Joined
Apr 27, 2026
Threads
6
Messages
41
Location
Georgia
I attempted to replace a bad O2 sensor today and sheared one of the mounting studs clean off the pipe. I am attempting to work on the other one more gently but TBH I was using a 1/4” socket to begin wi5 and barely put any toque on the one that broke so I’m not sure I can do too much to the other one before it too breaks. I’ve been soaking it every few hours with PB blaster and taking a torch to it but it’s not budged yet.

This leads me to the meat of my question. What would you do in this situation? My instinct is to take it to a shop, have them cut them off and weld on new studs. But I’m not sure if the labor required would end costing more than a new exhaust all together. That lead me in to thinking if doing so would be a good opportunity to have the sensors relocated to a spot that is a little less exposed to the elements and easier to reach for future me… and, well… then I thought I should probably poll the group to get input before I got carried away or reinvented the wheel.

So, in this case the exhaust is stock and all bolts and clamps on it are heavily HEAVILY corroded and unlikely to loosen without, at least a good fight. There are no leaks so it’s definitely useable but there’s no way to non-destructively pull the sensors or do any other service to it. Would you replace it with an aftermarket kit, have a shop replace the pipes or salvage the stock system?
 
I'd have to see the system and would feel my way forward through the options depending on how things went but I would start by putting effort into retaining the stock system if it is solid overall.

My 330k '97 is running the stock exhaust system and when I got it 100k and 10+ years ago I ran into issues like you describe when replacing the O2 sensors, the insulator/mounts and replacing the seal/gasket between the two cats, etc. I was really on the fence regarding full replacement but had time to tinker and once I had the O2 sensors replaced the rest fell into place pretty easily. The system has been trouble free over the last decade/100k miles and shows no sign of additional wear so it seems at this point that fixing it was the right approach. The stock system is made of good stuff and many non-stock replacement parts are not going to last nearly as long, especially in rust causing conditions.

Keeping the stock system could be a good excuse to buy a welder, if you don't already have one, to help with extracting broken off studs or patching up a few spots. You can get a welder for far less than a new, stock exhaust system and it may make keeping the stock system in good shape a lot easier. I think I used my welder to get one of the broken off O2 studs out and to patch a spot on the muffler which saved me needing to pay a shop to do these little tasks. I use one of the Harbor Freight Titanium 125 flux core welders and get great results out of it as an amateur. I've used other processes / machines and there are trade-offs but for my typically small, one-off tasks I like the form factor and simplicity of the 125 and don't mind the clean up when done.
 
If you snap the other one, get a new bung and weld it on top of the old one

O2Bung.webp


This would be easier than trying to pull a corroded pipe just to fix a stud
 
AFAIK the O2 sensors should be sitting at a specific depth to get a good reading (tip in the exhaust gas stream) so the old bung might need to be removed before welding on a new bung with studs??

The original studs were M8x1.25 but as mentioned Toyota doesn’t sell them separately but any generic M8 x 1.25 x ~30mm threaded stud should work.
 
jpoole said:
I'd have to see the system and would feel my way forward through the options depending on how things went but I would start by putting effort into retaining the stock system if it is solid overall.

My 330k '97 is running the stock exhaust system and when I got it 100k and 10+ years ago I ran into issues like you describe when replacing the O2 sensors, the insulator/mounts and replacing the seal/gasket between the two cats, etc. I was really on the fence regarding full replacement but had time to tinker and once I had the O2 sensors replaced the rest fell into place pretty easily. The system has been trouble free over the last decade/100k miles and shows no sign of additional wear so it seems at this point that fixing it was the right approach. The stock system is made of good stuff and many non-stock replacement parts are not going to last nearly as long, especially in rust causing conditions.

Keeping the stock system could be a good excuse to buy a welder, if you don't already have one, to help with extracting broken off studs or patching up a few spots. You can get a welder for far less than a new, stock exhaust system and it may make keeping the stock system in good shape a lot easier. I think I used my welder to get one of the broken off O2 studs out and to patch a spot on the muffler which saved me needing to pay a shop to do these little tasks. I use one of the Harbor Freight Titanium 125 flux core welders and get great results out of it as an amateur. I've used other processes / machines and there are trade-offs but for my typically small, one-off tasks I like the form factor and simplicity of the 125 and don't mind the clean up when done.
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Thanks for the suggestion and insight! One of the first things I realized when I got this truck is that a basic welder, and learning to use it, are going to be invaluable in repairing and maintaining it. I've already encountered no fewer than 10 situations over the last week where, if I'd had a welder, I could have done a "proper" fix or made the process of doing whatever it was I was doing a lot easier. From the looks of it, the bung has already been replaced once (just judging by the quality of the weld on one pipe vs. the other) or at least repaired at one point and, you're right, a basic entry-level welder at Harbor Freight, including a mask and gloves would run me probably $100-200 less than having a shop do the work considering all the labor that would be involved.

I guess the good news in all this is that, in the process of heating up the remaining stud with the MAPP torch to try and break it free I somehow "fixed" the existing O2 sensor so it's not throwing a code anymore. So, for now, I'm going to get a hose clamp to try and hold down the one bolt-less side of the flange to reduce some of the sound from the small exhaust leak that I now have and live with it. I've already dumped enough money in to this truck for one month.
 
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Might be worth asking a few Muffler shops (small independant shop) if they can repair/replace the bung, used to be they'd charge $20-30, but I guess these day's they might want a lot more.
 
I had a similar situation a few years ago on my Outside Pipe. If I remember I got a little lucky and the bolt snapped off with a little nub sticking up. The other side actually had the nut rust off and just leave a well rusted stud sticking out. My solution was to recut the thread on the full stud with a M8x1.25, put new gasket on, tighted down a bit and then use a HUGE amount Muffler Patch to essentially epoxy it in place on the other side. I think its been 5 years and it is still going strong! I know at some point I will likley have to replace the down pipes, and have started ordering all the parts, but since it has held up, I honestly just have let the sleeping dog lie. I keep a portable CO detector in the car in case any leaks pop up. I recently posted about the Driver side O2 sensor repair I did. PITA on that side to get any kind of wrench on the Die Cutter and lots of bloody knuckles but I was able to successfully re-cut both studs and put stock nuts and gasket right back in place! It was a miracle honestly. I thought I was going to be dealing with removing the header pipe which I am sure is rusted in pretty well.
 
tedwardd said:
I attempted to replace a bad O2 sensor today and sheared one of the mounting studs clean off the pipe. I am attempting to work on the other one more gently but TBH I was using a 1/4” socket to begin wi5 and barely put any toque on the one that broke so I’m not sure I can do too much to the other one before it too breaks. I’ve been soaking it every few hours with PB blaster and taking a torch to it but it’s not budged yet.

This leads me to the meat of my question. What would you do in this situation? My instinct is to take it to a shop, have them cut them off and weld on new studs. But I’m not sure if the labor required would end costing more than a new exhaust all together. That lead me in to thinking if doing so would be a good opportunity to have the sensors relocated to a spot that is a little less exposed to the elements and easier to reach for future me… and, well… then I thought I should probably poll the group to get input before I got carried away or reinvented the wheel.

So, in this case the exhaust is stock and all bolts and clamps on it are heavily HEAVILY corroded and unlikely to loosen without, at least a good fight. There are no leaks so it’s definitely useable but there’s no way to non-destructively pull the sensors or do any other service to it. Would you replace it with an aftermarket kit, have a shop replace the pipes or salvage the stock system?
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I took mine to a shop, for this very repair, and it cost me $503. Exhaust work has gotten idiotically expensive.
 
COS80 said:
I took mine to a shop, for this very repair, and it cost me $503. Exhaust work has gotten idiotically expensive.
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Being in California and just doing this.. New C.A.R.B. CA EO# cats (front and rear - 1997), front and rear exhaust sections with muffler and resonator (OE direct replacement) Denso O2 up and downstream sensors.

Cost with my discounts; just parts- $ 1203.21 (non CARB was about 430.00 less for parts)

2 hours to tear out old and install new.
 
I’m in the midst of changing out an 89 FJ62 exhaust. The Cats are good so I’m replacing from the muffler on back. I’ve owned it for the past 30 years and this is the first time it required any exhaust work. The previous owner had installed an aftermarket exhaust and used the 3/8” rods for supports. The exhaust that I ordered from SOR has the brackets (hangers) already welded onto the muffler and pipe. The type you see in the line drawings for SOR and other vendors.

I just stopped working on it because I can’t tell if the new “cushions” go on top of the brackets that are welded to the LC frame, or below it. If they go above the welded bracket, it looks like its gonna be really, really, tight because the muffler bracket (hanger) has to fit in there as well. It doesn’t look like it fits below because the resultant tilt in the muffler (tilted up towards the front of the LC) won’t allow the muffler/cat exhaust flanges to mate face-to-face. It touches at the bottom of the flanges and has a gap at the top. I’ll find out tomorrow when I try to squeeze it in between the bracket and the floorpan.
 
Borla is a good option. customer had one that was 15 years old, muffler started to rattle a little. They sent out a whole new system for free under warranty!
 
@landtank this is incredible. It make me so happy to see this. I’ve paid 2 different shops over the years to route exhaust over frame on two different 80s - not fully satisfied either time.

Excellent work! And I see you have the 93 ish heat shield in place over the frame as well. Nice.
 
Jeeper said:
@landtank this is incredible. It make me so happy to see this. I’ve paid 2 different shops over the years to route exhaust over frame on two different 80s - not fully satisfied either time.

Excellent work! And I see you have the 93 ish heat shield in place over the frame as well. Nice.
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This routing is the same as the GCC spec 95-97 FZJ80 1FZ-FE. I actually went with a pacemaker header, vibrant resonator and ganador vertex.
 
I didn't read the entire thread, but I'd simply replace the whole exhaust from the downpipe, all the way to the tail pipe. I'd also get modern high flow cats made for your vehicle (federal EPA vs California EPA emission compliant), just so you don't get a CEL or have trouble passing annual SMOG test. I'm sure there are bolt on solutions that already exist in the market.

You certainly ought to get a welder and start doing fabrication projects. However, i would NOT learn on an exhaust project. You'd have to become a great welder before welding on thin walled exhaust piping. You don't need a powerful welder, but you have to become a great welder to be able to weld upside down while laying on your back, and shoving the stinger around $hit, while getting $hit all over you and all that fun $hit. Yeah, as you can tell, I absolutely HATED welding up my own exhaust but I wanted it done my way since I have a turbo and I didn't make any compromises. I'd not do that again so I'm hoping my daughter will do it next time. She knows how to fabricate and weld but now going to welding school to become a pro welder.

Regarding the O2 sensors, this is your opportunity to change both sensors from the Toyota stud style to a screw in style if that floats your boat. Do realize that both sensors aren't the same exact Denso p/ns. Upstream one is called air/fuel ratio sensor, downstream is called a plain O2 sensor.

Oh and another thing I highly suggest is NOT to use Toyota style gaskets, flanges and $hit. The flanges with two studs, often bow in the middle once you torque down the hardware hella tight, and leaks start to form. I'd suggest using V band clamps for everything which requires no gaskets and a little bit of misalignment doesn't cause any leaks. You can take these things apart as often as you need to. Here's an example of a V band clamp at the tail pipe area, and one at the downpipe area. Since I'm not a pro exhaust welder, I chose not to butt weld everything, but used slip joints in order to prevent blowing through the thin walls and to prevent any goobers from dripping down inside the air stream. Yes, those V band clamps cost $30/each but well worth it for zero aggravation. I'm all about zero aggravation when I'm welding under the 80. I used 2.5" SS piping with mandrel bent sections.

1781113288700.webp
1781113669297.webp
 
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This was bought prior to the tariffs, shipping to the US seems to have stopped. While needing to build the jig to ensure the final piece would fit properly, I had thought that people could buy the system and divert the front section to me to rework it, but that doesn't seem possible right now.
 
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