OK, I have another thread in here on several things I've been doing with my 3.0, (https://www.yotatech.com/forums/f116/inspired-dive-into-3vze-91330/) but I'm now stuck with the O2 sensor. I've tried a week of repeated PB Blaster, blow torch, hammer, vice-grips and everything short of hacksawing the d@mn thing off. WTF?!? I've been able to get most of the rust off the bolt, but the nut looks like a round gob of rust. I can't get any size wrench to fit it, vice grips just twist on it. I've scrubbed the heck out of it with a stainless steel brush and I'm left with nothing that looks like a nut. WHAT IS THE SECRET?!? I'm about ready to cut the darned thing off! HELP!

 

How about grind it off?

 

spit on it!

 

Short of cutting it off, I'd try applying some Naval Jelly to it. It disolves the rust, and voila!

 

tobasco?

 

Got a welder?

Maybe you could weld a bar to it to pry on. Or break it off and weld a nut to the inside of it with a good head on it.

Otherwise, try using an angle grinder to grind new flat sides on it that you can get a grip on.

Lastly I'd either break it off and drill it out for a timesert or helicoil, or just drill a new hole in the pipe near where it is and tap it for a new O2 sensor and just leave that one in...

I think you can also drill a bigger hole and weld a nut onto the pipe over it for the sensor too if you go that route.

 

Sounds like it is time to replace the whole thing. New bung, new O2 sensor, and probably new pipe too. If you really want to save the pipe and bung you could try drilling out the old studs and retap or helicoil the holes for new studs but its probably not worth the cost or time.. Those things will rust into a pile of flakes and nothing you can do about it now.

 

well u sadi blow torch but blow torch it and touch a wax candle to it and when its still really hot it WILL come right off. The wax draws into the threads and lets them slide when its liquid. Did thsi on every bolt on the original exhuast system the other day on my 87 and every bolt that was completly rusted came off like new.

 

I had the same problem with my 94 runner, where after 5 Wisconsin winters the nuts were little rounded lumps of rust. I ended up taking a carbide cutting tip (forgot the part number) on a Dremel to shave a deep enough groove into the side until I could break the nut halves apart with a flat head screwdriver. Be careful not to grind the threads on the studs though- they are slightly harder metal but it can be hard to distinguish-; I didn't have to grind the nut that far. Oh yeah, don't forget the eye and hand protection- little sharp shards of steel fly everywhere when you do this and get embeded in your fingers when you handle them!

 

Coming back to this. I am looking at replacing my O2 too and the nuts are pretty much rounded and rusted/baked on dead. What puzzles me is that threads of the bolt are ... somewhat ... flat. I.e. they are not damaged or anything but the bolt just seems to be like a rod?? Are those threads filled with something or what? A few months ago a garage took the sensor off and put it back on so I assume that is why the nuts are rounded but what is with those bolts?

 

I know EXACTLY what you mean; mine looked the same way. I finally got them cut enough with the dremel and when the bolts screwed off, the threads magically appeared! Weird!