Oxygen Sensor Thread Pitch / Sensor replacement ?

[cnavarro]

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?

[cnavarro]

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.

[john70t]

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.

[Zef]

Helicoil is your friend in this case.

[MotoSook]

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

[cnavarro]

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 :-)

[DW SD]

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

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

Doug

[Zeke]

Originally posted by cnavarro
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 had nothing to lose. Good job.