question about removing O2 sensor

[dtziheucdavis]

I have a 3rd gen 4runner and would like to change out my O2 sensors (both upsteam and downstream). Problem is, the nut is almost completely rusted off, and I'm having trouble getting the old sensor off. Does anybody have some advice for how I can do this?

Here is a pic:

Imgur

 

[willhaman21]

Mine weren't quite as rusted off as yours, so I still had something to clamp to. A small set of vice grips is your best bet, and get it as tight as humanly possible. That is, if you can find something to lock them on to. Otherwise, I would assume a torch and a small hammer in there would work?

 

[meRockboost]

Soak them with pb blaster or fluid film overnight. Spray them again, drive around to warm them up and hit th with a 6" vise grip plier while warm. I just went through the same thing and almost gave up until I drove around to warm them up

 

[gamefreakgc]

There are no nuts holding on your sensor, those are the studs attached to the exhaust pipe. If it's built up crud that's holding the sensor on then try threading on a new nut and should knock that stuff off (don't cross-thread though! not too hard).

This is what it would look like if there were nuts on there and badly rusted:

 

[eanema]

I recently replaced mine. What I did was drive around to get the exhaust good and hot, hose it down with liquid wrench/penetrating oil then scrape it with a wire brush to remove the loose rust. Repeated that a few times over the course of a day, then went under with a wrench and loosened it. It's supposed to be a 12mm nut, but I used a 10mm on one nut and an 11mm on the other and managed to get them off without too much of a fuss. Definitely give the vise grips a try though.

The hardest part about this is fishing the connector overtop of the transmission and reconnecting to the electrical harness. That was a pain...

 

[Arnezie]

Wire brush and wd40. Mine were bad but not that bad.