Failing to remove O2 Sensor

[roger]

Following the arrival of my O2 sensor socket I thought I would spray my manifold cover off the car this afternoon following a painfully poor attempt at brush painting some weeks ago.

I got everything undone EXCEPT the LH O2 sensor  s:( s:(  . The RH came off easily, but no amount of (reasonable) force would shift the LH one. I was a bit wary because I didn't want to damage the sensor, and for this reason I didn't use WD40.

Anybody had the same problem? Can I use brute force, hit the breaker bar with a hammer, use WD40, or what?

All back together again now, but I will try again if anybody can give me the right tip.

Thanks

roger

[SteveJ]

Given that the O2 sensor element is made from ceramic, impacts of any sort should be avoided as it may well shatter. Also you should avoid the use of WD40 as it can contaminate the sensor (it has openings on the exposed part of the sensor to get a reference value from the atmosphere)

Sorry I couldnt give you a way of shifting said O2 sensor, but at least you wont need to buy a new one cause the old one got broken by incorrect handling  s:? :? s:?

[roger]

Steve, thanks - as I thought, that is why I was quite "gentle".

I'll ask MrT to check the precats when it has its service, and hopefully they will have the problem, and leave it nice & loose for me!

Thats assuming 1. They actually do do it, rather than saying they have, and 2. They don't leave me with a broken sensor.   s:roll: :roll: s:roll:  

roger

[SteveJ]

I did forget to mention - generally they are easier to shift if the manifold is hot, but I would suggest you just loosen it and then allow to cool before fully removing.

[aaronjb]

I've always used PlusGas to unsieze the threads on O2 sensors personally - just avoided spraying it all over the sensor itself and hit the threads at the base.. so far, no dead O2 sensors, but maybe I've just been lucky..

That and a really, really long breaker bar, and lots of brute force (the first set I removed had been on the car for 12 years  s:lol: :lol: s:lol:  they took some extracting.. the second set had been on a UK car for the same amount of time - ended up having to remove the exhaust manifold and use a huge vice plus a bit of scaffold!)

I'd agree about not smacking the breaker bar with a hammer though  s:) s:)

[SteveJ]

I've always used PlusGas to unsieze the threads on O2 sensors personally - just avoided spraying it all over the sensor itself and hit the threads at the base..

The '2s sensors have a square shoulder which acts as the gas tight seal against the manifold, so there is no access to the thread from outside - the only route to get at the thread is from inside the manifold (the removal of which is even more problematic than the O2's with the risk of rounded nuts [fnar fnar!] or sheared studs)

Leave it to MrT - that way if they break it they have to fix it (having said which IIRC a couple of dealers have refused to remove O2's or have made it clear that it is at the owners risk)

[Tem]

The RH came off easily, but no amount of (reasonable) force would shift the LH one.

I didn't get any of them off with reasonable force, they were bloody tight  s:? :? s:?  I just applied more than reasonable force with longish lever and they came off in one piece...but if you're in doubt, let someone else open them  s8) s8)

[spit]

Like you, my RH sensor was a breeze, the LH one was a bit of a pain.

A (quick) squirt of Plusgas - left overnight - and it was still stubborn. I managed to get it free by putting a 3/8" to 1/2" adaptor on the sensor socket, and plugging this onto the torque wrench. By slowly upping the torque, the "clicking" of the wrench eventually popped the sensor free.

With a breaker bar and hammer, its difficult to keep everything square when you're hitting so off-centre. In contrast, the relatively small shock of the torque wrench click gets transmitted centrally and evenly around the socket, and helps free the sensor seat evenly.

I've used this method a lot on m'bikes where an impact driver or off-centre shock would be detrimental. It doesn't always work but is based on a sound principle!

[roger]

Thanks for all the responses.

One thought I had at about 3.30 this morning! Since I can get one sensor out, will the cover slip over the top of the other, or are the sensors bigger than the hole in any way?

Probably give that a try this afternoon, unless somebody can come back with a definite.

Thanks

roger

[spit]

One thought I had at about 3.30 this morning! Since I can get one sensor out, will the cover slip over the top of the other, or are the sensors bigger than the hole in any way?

It may do Roger, particularly as the angle of the LH sensor is less pronounced than the RH one. I think the hole is big enough to clear the block connector too (but don't quote me on any of this) I know for a fact that it won't come off with BOTH sensors in place!

I'm thinking its worth a try - it will improve access to the rogue sensor. Anyway - its Sunday - national tinkering day, so its your birthright to give it a go!

Another tip - if you reassemble with a small amount of Copaslip on all of your threads, they'll hold tight but come off easier in the future.

[roger]

I'm thinking its worth a try - it will improve access to the rogue sensor. Anyway - its Sunday - national tinkering day, so its your birthright to give it a go!

Thanks spit for the encouragement. Success.  s:bounce: :bounce: s:bounce:  

Cover came off with LH sensor in place no probs. Currently on 3rd coat. Still couldn't get sensor out, tried when it was hot, warm and with cover off. Having said that because the plan came together again I didn't try too hard.

Long live national tinkering day  s:D s:D  

roger

[spit]

Nice one matey!