Oxygen sensor woes

[FireFox31]

I'm trying to fit a used front oxygen sensor in Geronimo the 2000 V70 and it's been a struggle.

I received a used O2 sensor still in a cut off piece of exhaust. I sliced off the exhaust piece but cut the sensor threads on one side. Do you think I've ruined the sensor with the slice, allowing exhaust to escape?

I'm going to the and remove the failed sensor from below using a breaker bar and a sensor socket. It's the only way I see to get leverage. Do you have any other methods? Thanks.

[abscate]

Just a little dab of high temp JB Weld on that flat sealing surface and you are good to go

Heat and cool, heat and cool, heat and cool is the key to getting these off, not torque

[Krons]

I was thinking high temp j-b weld too before I saw Abscate’s reply. Should be able to pick it in there with a toothpick and ‘mold’ the threads to match. Almost like free loctite!

[abscate]

Leave the threads alone. Just make the seal surface flat

[FireFox31]

I had someone at the Makerspace put a small tack weld on the non-threaded part of the cut. I may add JB Weld later. I first need to confirm that this sensor will clear my O2 heater code.

I'm using a Mini-Ductor inductive heating coil on the exhaust hold. 30 seconds of heat, 10 minutes to cool. Gets quite hot but I think I might have to go hotter.

[FireFox31]

I ran the O2 sensor port through at least 12 heat/cool cycles, each time heating it more. After 25 seconds with the heater, it the sensor and exhaust began ticking. At most, I let it heat for 50 seconds. For comparison, a large rusty nut heated for 8 seconds can't safely be touched, so 50 seconds was a darn long time. I'll try removing it tomorrow. Hopefully the high temp JB weld will cure within one day so I can fix and install the sensor only once.

[abscate]

I heat those to cherry red with MAP and O2 to budge them. Several times.

You need to get that surface flat so it seals against the flange on the cat.

[foggydogg]

I'm with the good Doctor, spend some time handworking the surface of the hex that contacts the flat of the sensor bung. There are crush washers available that would help seal it too, NAPA may have the right diameter. There isn't a lot of gas pressure involved here, it doesn't need to be unGodly tight, it just needs to not leak exhaust under your feet.

[FireFox31]

Regular and high temp JB Weld can withstand 550 F. Extreme temp JB Weld can handle 2400 F. Which do you think I'll need?

I'll see if I can reuse the crush washer from the current O2 sensor. It measures roughly 17.7 mm ID, 22.5 mm OD. No idea where else I could get just one of those.

[abscate]

I think I would go extreme. Cats get hot, and I have seen 500F at that down pipe in the driveway