Tips for removing corroded nuts?

I last posted about the loose rear oxygen sensor (or air/fuel sensor) I discovered rattling under the truck. After getting all the parts to replace the sensor, I went to take it off the exhaust. But so far I can't remove the remnants of the nuts that were holding the sensor on. Here's what they look like:

Does anyone know how I might remove what's left of the old nuts off the posts without destroying them? I've used PB Blaster, but the nuts seem to be fused to the posts.

 

Not really any good options IMHO. Both options are labor intensive. Both options mean removing the headers.
1. Get new/used headers?
2. Take these out, drill and retap.
Sorry, but, that's the best I can do.
Good luck.

 

saturate with break free multiple times and let soak overnight
if they fail to break free...
try using heat (torch)

and if all else fails... ^

 

As Rusty as that looks how long till the pipe needs replaced ??.

Myself I just drop the part the sensor is in cut the old bung off and replace with a new one

Once it has been replaced I seldom have any more problems

 

Thanks for the responses, guys.

About the pipe: yeah, it's not in great shape. The previous owner already replaced the rear half of the pipe (past what can be seen in the picture) and muffler, so that half of it is new. I don't have any welding experience, unfortunately, to go in there an cut pieces off. I assume I'd have to replace the entire thing?

I'll give Breakfree a try and heat - I don't have a torch, but my wife has a little chef's torch that might do the trick. Can't hurt...

 

Thanks for the advice. What tool would you recommend for cutting off the old sensor?

 

It is a double ended stud. See if you can get two nuts on it (or vice grips clamp tight as hell) and break it loose.

 

If you go heat, take a can of compressed air (like keyboard cleaner) flip it upside down and blast the studs. It will cool them insanely fast if you can't break them free with heat alone.

 

I used 10 or 12mm deep socket and mini ratchetthewere so corroded they literally fell apart you may be able to just pull on the sensor and those rusty nuts willfall apart then pick out metal off the studs with needle nose pliers. get new nuts at home depot they are 8mm x1.25, you wont need locknuts or washers

 

use a deep socket don't use a regular one the are too shallow and u wont get a good bite, I bet you can just pull that sensor off with your hands the nuts will just fall off with it that's howe mine went

 

Thanks for all the tips. I'll give it another go tonight and see if I can make some progress breaking the nuts down. I soaked them in PB Blaster last night to prep them.

 

once you get the nut moving you can almost twist it off with your fingers or the disentagrate if its the front sensor its tough to work because of confined space use a mini ratchet and deep socket youll get them, open end wrenchs don't bite those nuts as good as deep socket

 

6 pt on whatever you use or those extractor socket things once you strip them. I would try the doublenut option on what's left and try to get studs to come out of pipe. Then go get news studs/nuts. Seems a bunch less tedious IMO.....if it will actually unscrew vs just breaking off the studs. If it seems that is what is going to happen then go to one of the other options unless replacing pipe is next option.

 

@98tacoma27
Do you mean a metric die like this (link to Home Depot)? I just managed to pry the old sensor off, so I could definitely get a die onto the stud now to repair the thread.

 

Yes a metric die like you linked.
I would first take a hand file and try to get as much of the old nut off of the stud as you can. Just don't go to deep and damage the stud, threads. Then re thread it with the die.

 

cool, easier fix

 

Good news: I successfully finished the repair and thought I'd give you all an update. I also thought it might be helpful to someone with a similar problem in the future.

I decided to get a 8m x 1.25 metric die and try to repair the studs. My local Home Depot didn't have an 8m x 1.25 die in their standard set, so

$9 Century Drill & Tool 97611 Metric Hex Die, 8.0x1.25

I ordered one directly off of Amazon with some thread cutting oil. The die worked great: as soon as it bit into what was left of the corroded nut, it loosened it and began to turn it down the thread (there was space, since I had pulled the old sensor off over it). Spraying everything again with PB Blaster the day before probably helped.


After a few twists, I was able to set the die aside and easily turn the remains of the nuts off the stud. Once they were off, I noticed that the old gasket had become partially fused onto the mount. You can see some pieces of it around the bottom of the studs here (I had already been working on it when I took the picture):

I used a small file and partly filed, partly chipped it off until the surface was smooth, while trying not to damage the thread on the studs. After that, I got my new sensor and gasket and went to work installing it.

But first the wires and tubing: There was a bracket for the tube (covering the wires) built into the frame of the truck, guiding it away from the exhaust pipe. You can pull this bracket out and open it (I used the point of a razor to lift the tab that opens it). Then I snapped the new cable in and put it back in the frame.

When you attach the connector, make sure you position the grommet (the rubber part that goes into the bottom of the cab) so that you have roughly the same length of tubing as the old sensor did.

After all that, I put the gasket on (the side with metal around the edge is supposed to face down) and secured it with lock nuts:

I didn't have any anti-seize handy, so I soaked the nuts in PB Blaster before putting them on. There was some debate online about whether to disconnect the battery. I left it connected, and the engine light stayed off when I started the truck up. Runs great!

This is the first time I've made any kind of repair like this, and I want to thank you guys for all your advice. I couldn't have done it without you.