ok what is up with the nuts they use for the o2 sensor flange? I have a '94 4 runner, non california spec. it's not a normal nut on it, none of my wrenches or sockets will fit it. is this something toyota did so you would have to the truck into the dealership so they can rob you to change the o2 sensor? does anyone know what kind of wrench fits so i can go buy one without being totally blind looking for something that fits?

 

You will need a 12mm 6 point deep socket on something like a 1/2" or 5/8" ratchet. Ideally use an impact wrench and a good week long soak in PB Blaster to take em off.

When that failed on my 13y/o o2 sensor, we broke the old o2 sensor off, then bent the heat shroud out of the way, then used a set of vice grips to remove the nuts.

A ROYAL pain in the arse, but it worked out and now I'm up 3-4mpg across the board in driving.

Steve

 

12mm doesn't fit on mine. too big. it's not a normal nut anyways. does anyone else who has a 94 4 runner know what kind of wrench i need to get these off?

 

Is it the kind that has a flange held in by two nuts?

If that is the case, they are not an odd size at all. Most likely they have rusted or corroded a bit that will make them a little larger then normal. Soak them in a rust penitrant, PB Blaster is a good one and then use a 6 point socket and pound it onto the nut and wrench it off.

Gadget

www.GadgetOnline.com

 

no it's not that it's really an odd size, it's not a normal nut. it doesn't have six straight sides. i'll try to get a picture of it so you know what i'm talking about.

 

Sounds interesting. Post the picture so we can see what you do.

Gadget

www.GadgetOnline.com

 

I just replaced my o2 yesterday. I dont remember what size I used but I did notice the nuts looked a little off. My socket set worked fine on it though. And do use liquid wrench or similar product at least a day before. My install went as smooth as silk, 15 min tops.

 

the nut on the right kind of flares from top to bottom so there are no real flat sides to grab with a wrench or socket. the nut on the left is the result of trying.

 

OK, those are stop nuts. They are used because of all the vibration that occures in the exhaust system. The lock onto the shaft of the stud and prevent the nut from backing its self off.

IGNORE all that stuff at the top of the nut. That is the part that clamps on the shaft of the stud. Look at the base of the nut you will see a standard 6 sided nut. Slip you socket down to the base of the nut where those six sides are and take it off like a normal nut.

Gadget

www.GadgetOnline.com

 

another nut joke commming on........

..... a picture of your nuts on the internet .... priceless!