Put new oxygen sensor in my car.(6cyl). Did not have any problems getting it out it was not rusted in. The problem I am having is that it came out twice today after I tightened it. Can I put some sealant on it or can I use the stuff that plumbers use (that white tape)?

either you got the wrong sensor or the hole is stripped. you'll have to have it repaired. I don't think there is a "helicoil" for that. no, sealer won't hold it if the hole is shot.

Hmm, if it is tightening up it should have threads left. How tight is it being torqued?

And it should have anti-seize carefully smeared on the threads (none can be past the last thread) as coming out is opposite of the normal problem with O2 sensors.

Ahhh, just weld it in

There is lots of thread there. It is not stripped. Just seems to back out when driving. I use to get a code for the sensor but since I put in the new one the code has dissapeared. The car runs a lot better. The old one use to give a strong exhaust smell and gas mileage was terrible. I just used a wrench to tighten it down (hand torque).

Maybe a little red,high-temp silicone would help.Works up to 1200+,as long as it's put onto a clean surface.

Those sensors have pipe threads, so the tighter you screw them in the tighter they hold. DANGER: tighten it too much and something will break or strip out. The manual says to torque it to 30 ft/lbs. You might try using a torque wrench next time.

DO NOT use silicone sealer anywhere around the oxygen sensor!!! Even a small trace of silicone will contaminate the sensor and ruin it. In fact, it's not a good idea to use any silicone sealer at all on the engine unless it is labeled "sensor safe"

All the O2 sensors I've seen have a gasket like on a spark plug,and a trace of silicone there just isn't going to harm anything,as long as you don't dip the whole thing,like it's ranch dip or something.
I'd try and use a torque wrench,or if you can't fit one up in there,try flexing the wrench against another bolt somewhere else on the car to get a feel for the torque value that's required.

bats, the O2 sensor is not NPT threaded. Wish it was, be less of a pain in some ways but would also be more prone to fusing into the bung.

Yeah, sounds like the thing isn't tight enough. It did come with the sealing washer didn't it? If that's missing or wrecked it won't be right either.

Anti sieze should only be on the threads. don't smear it on the washer. If it is on the washer or the surfaces the washer touch then clean it off.

I meant the water temp sensor had pipe threads...yeah, that's what I meant. Jeez Ogre, ya gotta always prove I'm human and make mistakes don't ya...LOL.

Just saying the word *silicone* around an O2 will contaminate it.

Terry