BMW e46 ZHP Post cat O2 sensors

[danewilson77]

First and foremost......Get a torch before you even put a wrench on one of these sensors.



The post cat O2 sensors are proving to be quite the formidable foe.

The sensor on the left is forward and the sensor on the right is aft (for orientation).

I was able to heat and loosen the forward sensor fairly easily. It's in there finger tight.

>Orientation pic


But...the aft sensor is badly rounded now, and I'm running out of idea's. I have 20mm, 21mm, 22mm, 13/16" open ended wrenches available plus the O2 sensor wrench (used this on the forward one and will not fit on the aft one). Of course I have a torch as well. Throw me some idea's fella's and I'll hit it after work again. Thanks...

[Dave1027]

Try soaking the hell out of it with PB Blaster and then clamp a vice grip onto it hard as you can. It will go.

[danewilson77]

OK.....

I had been doing that......then went to heat........but will go back to that (pending other idea's) when I get home.

Thanks Dave.

[Hornung418]

You could undo the manifolds from the exhaust, unbolt the transmission from the mounts and lower it to gain access to the post cats that way.

From a GS3, this was sent.

[kayger12]

Torch followed by vice grips with a breaker bar?

[danewilson77]

You could undo the manifolds from the exhaust, unbolt the transmission from the mounts and lower it to gain access to the post cats that way.

From a GS3, this was sent.

This entered my mind as I was lying there on my back.....but, I would be trying to get more rusty shit apart....hehe. I'm gonna leave that for last resort.

Torch followed by vice grips with a breaker bar?

OK. Breaker bar added to equation. I just need to get a good grip on it with the vice grips, then it will probably come.

Be advised, at this point, I'm not even sure I can get vice grips in there. We'll see.

Thanks all so far.

[LivesNearCostco]

What is the official (original) size of the wrench flats on it? You could try a flare nut wrench set, metric or SAE, depending how rounded the flats are. This Sears Craftsman metric 5-pc set only goes up to 18mm but their Gearwrench flex set has a 19mm and 21mm. The HF metric 5-pc flare nut wrench set has 19mm and 22mm but no 21mm. It will grip 4 or 5 flats instead of just 2.

What I did with my old saturn was unplug the O2 sensor cable and thread the closed end 22mm (or maybe 21mm?) wrench over the cable and down to the sensor. That would give best leverage on the sensor but not sure you can fit it down by the side of the engine and manifold.

[danewilson77]

It's a 22mm.

No way to get a box end on it.

Please explain a "flare nut wrench".

[wsmeyer]

It's a 22mm.

No way to get a box end on it.

Please explain a "flare nut wrench".

Just imagine a box end with one of the 6 sides missing

[danewilson77]

Try heating just the bung on the manifold and use a chisel and hammer to knock the sensor counter clock wise. COULD BE AN OPTION.
---------------------
You could cut the sensor down to the nut to get ready to weld on a bolt and try to go from there. NOT AN OPTION.
---------------------
LOCKTITE has a new freezer spray that you spray the same way as you do WD40.
As it minutely shrinks the bolt (your sensor) the lubricants are supposed to wick into the threads and provide lubrication. COULD BE AN OPTION.
---------------------
Its new and I haven't tried it. But its in the trade magazines as better than WD40 type sprays that rely on soaking penetration.
---------------------
Remove the cat to do it on the bench. I am a pessimist. UGH.
---------------------
I learned from my mechanic buddy that a pipe wrench works well on rounded off stuff, the more you turn it the more it grips. NOT AN OPTION.
---------------------
Yeah...put the whole pipe in your freezer, then heat the **** out of the bung...it'll come out. LMAO.
---------------------
Saw the sensor out leaving the hex part (that is rounded)
then get a irwin set of bolt extractor sockets and bam.

will take 2 seconds, ONLY IF I REMOVED THE CAT.


---------------------
Weld a wrench onto the o2 sensor and let it sit for a bit or buy a drill bit that will work and stick a bold or somthing through it. NO.