Oxygen Sensor Thread Pitch / Sensor replacement ?
 

Stupid question - I was able to get the oxygen sensor off of my 91 964, but upon closer inspection the top 50% of the threads are either rusted or cross threaded - the sensor that came off appears to have been forced on.

So what are my options - I would rather leave the cat in place. Can I use something like this:

http://www.sjdiscounttools.com/hel4833.html

They sell them with M18x1.4 and M18x1.5, so which is it?

Ideas, suggestions?

I have also thought of running a tap through it, but what are the chances of getting the threads to match up, since there aren't any for at least 2mm of the bung.

Take off the cat and have a new bung welded on at a muffler shop.
Or get a threadpitch gauge and order the right tap.
There was a trick tap set mentioned in one of the threads that opened upafter insertion- so that the shavings were pulled out with the ap.

Helicoil is your friend in this case.

Charles, it should be 18X1.5. I'd just weld a new bung on there. Bungs are a few bucks a pieces.

I was able to find a tap at Napa and ran it through very carefully with some tap magic and it cleaned up very well. New sensor threaded in smoothly - I made sure to use good anti-sieze there too! When and if it needs changing again, I'm sure the bung will be toast and that will give me an excuse to put in a cat bypass :-)

You could also cap the bung and weld a new one in.

Glad you got it sovled for the next 50k miles, though!

Doug

You had nothing to lose. Good job.