O2 Sensor stuck in Cat Bypass.....
 

When I last had my Cat bypass off the car, I tried in vain to remove the O2 sensor, but it was totally stuck.

Now, I consider myself to be the master "shadetree mechanic", but this puppy would not budge.

Has anyone else encountered this issue? Will I have to by a new bypass pipe in addition to a new 02 sensor?

I am hoping that someone has encountered this issue in the past.

If your bypass pipe is still attached... try driving around for about 30 minutes and then throw a wrench on it.

OR

Remove the pipe and apply heat from a torch to the surrounding area.

Soak the thread area for a few days with penetrating fluid before attempting either method.

More info: how to replace an oxygen sensor part (1/2) - YouTube

+1

After the above, you can cut the neck off the sensor and put a normal six point socket on the O2 hex with a breaker bar for leverage

Chris,

I replaced my O2 with the exhaust out and it was a bollywood production... Eventually resorted to cutting the wires off the sensor, making a metal mask to allow the seat area to be heated and the sensor to be cooled. Used a long socket and a huge vice grip (major leverage). Before anything I beat the sensor (respectfully) a number of times in hopes of breaking some adhesion.

By heating the sensor's seat area and cooling the sensor itself, it eventually wrenched out (with significant leverage.) 2 people required --- one to hold mask and cool sensor with wet rag... the other to torch seat area. Obviously this path won't work with parts installed on the engine.

Thinking now... had that not worked, perhaps the sensor could be cut off and the remainder drilled (carefully) out. A bit risky.

You might want to post in the "engine rebuild" section --- those guys deal with stuck stuff all the time.

http://forums.pelicanparts.com/uploa...1376575951.jpg

http://forums.pelicanparts.com/uploa...1376576677.jpg

That happens a lot to me lately.
First, heat does help a great deal from a MAPP gas torch. As will cutting it off and use an impact wrench.
Second, even if the threads are all messed up, a set of 18mm 1.5m tap and die will clean that up (Expensive set)
Third, if you really mess up the bung, and need to save the pipe, an exhaust shop can cut out the bung and weld in a brand new one for $30.
Fourth, replacing an o2 sensor is not an expensive option if you go the universal route.

All four have happened to me in the last 6 months.

Wow! I feel much better after reading these replies. I thought the world had singled me out for punishment on this one.

Yes, the bypass is back on, so I'll try the Penetrating Oil/Heat method.

MAAP gas will get it hot enough after SEVERAL minutes. Heat, bang on it good, spray penetrant, wait a couple of minutes, repeat a couple of times then put the wrench on it.

If you have a cut off wheel, angle grinder, even a pedestal grinder cut it off flush at the heavy metal shoulder right above the hex. Then you can bang on that and not bung (heh heh) up the hex.

http://forums.pelicanparts.com/uploa...1376584628.jpg

I had this problem too...

Cut off the sensor part at the hex like other people said and then A LOT of PB Blaster and a large breaker bar for leverage, it finally came out. After you get it out, use a tap or thread chaser to clean up the threads.

if its in that bad .. i just cant see PB blaster or any chemical doing any good, i just cant see how it can penetrate. maybe its just me but i think its about the heat and leverage.

Agree. Heat and shock from wacking it when hot can bust up the cooties a wee bit to allow some of the penetrant to sink in.

Spraying penetrant on a cold joint could take days and days.

Once a disturbance in the "force" has been delivered the penetrant will do it's job. That's one reason why I reef on it clockwise as well as CCW.

If you have the right amount of heat, though, that's all you need. You can bust it loose with a crescent wrench. MAPP gas/propane won't get you to that point usually.

Mine was stuck in the pre-muffler (track only configuration). It had only been there about a year and a half, but was really stuck.

Rather than taking the "we had to destroy the sensor in order to save it" route, we just got another O2 sensor for the cat. A lot less stress every two years.

Acetylene always wins.

so you got like 5 bungs on there over 10 years ? lol

One recommendation... Before installing your next O2 sensor, spray some of this on the threads:
Corrosion Block - Corrosion Control and Inhibitor products

This stuff should help with the next removal.

I'd be careful to only spray it on the bung - not sure it would play well with the sensor.