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.

http://i1015.photobucket.com/albums/af278/nicee46/Maintenance%20and%20Misc/MAPTorchLowes.jpg (http://s1015.photobucket.com/user/nicee46/media/Maintenance%20and%20Misc/MAPTorchLowes.jpg.html)

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
http://i1015.photobucket.com/albums/af278/nicee46/Maintenance%20and%20Misc/fb7e12c8-193a-437f-bae4-eac02a08a422.jpg (http://s1015.photobucket.com/user/nicee46/media/Maintenance%20and%20Misc/fb7e12c8-193a-437f-bae4-eac02a08a422.jpg.html)

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...

http://i1015.photobucket.com/albums/af278/nicee46/Maintenance%20and%20Misc/a4c4a9db-6528-4a3a-9aed-0073c6511a88.jpg (http://s1015.photobucket.com/user/nicee46/media/Maintenance%20and%20Misc/a4c4a9db-6528-4a3a-9aed-0073c6511a88.jpg.html)

[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.
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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.
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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.
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Remove the cat to do it on the bench. I am a pessimist. UGH.
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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.
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Yeah...put the whole pipe in your freezer, then heat the **** out of the bung...it'll come out. LMAO.
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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.

http://i1015.photobucket.com/albums/af278/nicee46/Maintenance%20and%20Misc/bolt-extractors-802.jpg (http://s1015.photobucket.com/user/nicee46/media/Maintenance%20and%20Misc/bolt-extractors-802.jpg.html)
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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.

[Newjack]

Maybe try to file down the rounded edges so that you can get a good grip on it? If you can manage a solid grip on the thing a breaker bar (as previously suggested) might help.

[danewilson77]

True. I had thought of that. filing will most likely occur prior to cat removal.

[LivesNearCostco]

Picture of HF flare nut wrenches. The slot lets you slip it over the O2 sensor cable or brake line.
http://www.harborfreight.com/media/catalog/product/cache/1/image/9df78eab33525d08d6e5fb8d27136e95/i/m/image_20638.jpg

[danewilson77]

OK. Got it.

[midlandtech]

PB blaster, let car idle while in the air so the exhaust heats up, then PB blaster again. That was how I got my trucks cats and O2 sensors out. Granted I didn't have a rounded bolt to deal with at the time either. Perhaps this in combination with a BFW

[danewilson77]

OK. Thanks.

[alexandre]

Cut the cable to allow box wrench to go on ?

[danewilson77]

Cut the cable to allow box wrench to go on ?

Nope. Can't get an O2 sensor or box end wrench on it.

Sent from my HTC6435LVW using Tapatalk 2

[LivesNearCostco]

Dane, I'm in suspense... what was the solution to getting it out?

[danewilson77]

Dane, I'm in suspense... what was the solution to getting it out?

It's not out yet. I can rotate it back and forth about 180 degrees.

HTC DNA, Williamsburg, VA

[LivesNearCostco]

well don't go back and forth, keep turning it counter-clockwise!
:marvin

[danewilson77]

well don't go back and forth, keep turning it counter-clockwise!
:marvin

Ha!

HTC DNA, Williamsburg, VA

[danewilson77]

This is turning out to be quite the little maintenance fiasco. :shifty

1 down, 0.63 to go.

http://i1015.photobucket.com/albums/af278/nicee46/Maintenance%20and%20Misc/IMAG0518-1.jpg (http://s1015.photobucket.com/user/nicee46/media/Maintenance%20and%20Misc/IMAG0518-1.jpg.html)

HTC DNA, Williamsburg, VA

[danewilson77]

That's bastid is coming out today.

http://i1015.photobucket.com/albums/af278/nicee46/Maintenance%20and%20Misc/PicsArt_1367073974875-1.jpg (http://s1015.photobucket.com/user/nicee46/media/Maintenance%20and%20Misc/PicsArt_1367073974875-1.jpg.html)

HTC DNA, Williamsburg, VA

[kayger12]

https://www.youtube.com/watch?v=RsxaDJAszjs

[danewilson77]

https://www.youtube.com/watch?v=RsxaDJAszjs

:rofl

HTC DNA, Williamsburg, VA

[wsmeyer]

That's bastid is coming out today.

That little guy had no idea what's about to happen

[Johnmadd]

Pipe wrench, mmmmmmm, good idea. :shifty

[danewilson77]

Won't fit.

HTC DNA, Williamsburg, VA

[BimmerWill]

Looks like a nightmare Dane, are you getting a code for the sensors or just wanting to replace them?

I would think that with all the heat and the PB blaster in there it would have broken loose by now especially with all the soaking that has occurred. It sounds like the majority of the problem with it is the extreme lack of work space going on in there. I can't think of anything that you havent already tried, at this point you might have to remove the header in order to actually get it off, especially being rounded off. If you can't get a closed or flare wrench and a breaker bar on there it may be your only option at this point.

Perhaps loosen it that 180 and spray some more PB down in there and keep working it back and forth. What is in the way from the bottom other then the heat shield and what not?

[danewilson77]

I was getting catalytic convertor efficiency code.

Still working it.

HTC DNA, Williamsburg, VA

[LivesNearCostco]

Here are some fringe suggestions Dane. May or may not help, but easier for me to type than for you to go to FLAPS or Lowe's.
1) Buy some Freeze-off. Heat manifold with torch then spray freeze-off only on O2 sensor to shrink it
2) Remove or at least disconnect and lower exhaust to give you more access room (use PB blaster first on the 4 15mm exhaust nuts)
3) Are you sure you can't thread a box-end wrench over it, maybe if you cut the sensor wire and remove exhaust?
4) If not willing to cut sensor cable, try the 21mm or 22mm flare nut wrench... really! (along with heating and freezing)

[Johnmadd]

Is it at the shop now?

[Johnmadd]

If so which shop?

[danewilson77]

No. Not at shop. I drove the zhp to work today. Ran like butta.

I think I may put it in the shop after meet.

I just need an exhaust shop to pull the o2 sensor, and stick the one old one in I removed, so I can drive it home.

HTC DNA, Williamsburg, VA

[LivesNearCostco]

Dane, I have to eat my suggestions about the flare-nut and box-end wrenches. Was just under the car to replace steering guibo and took a close look at the 2nd (rearward) post-cat O2 sensor. It looks like it *might* be possible to get a box end wrench on only if you cut the cable and disconnect the exhaust, but it's not a sure thing even then. Maybe if the flats aren't too rounded off, an O2 socket used, with an extension. Otherwise hack-saw off most of the sensor and use a 21mm socket or broken bolt extractor on it.

Or drive this from below with 3/8" extension?
http://static.summitracing.com/global/images/prod/norm/wmr-w84008_w_m.jpg

Which O2 socket do you have, the in-line drive with slot or the offset type? I suppose it doesn't matter if you already tried one and it's slipping.

[danewilson77]

Its completely rounded. Still tight as....

HTC DNA, Williamsburg, VA

[WOLFN8TR]

Wow Dane what a nightmare! Hopefully I will never have to go thru this situation.

As previously stated Heating up the exhaust and spraying the Sensor with Freeze spray and go for it! I've used the can of air upside down before, works good.

Good Luck!

[Johnmadd]

No. Not at shop. I drove the zhp to work today. Ran like butta.

I think I may put it in the shop after meet.

I just need an exhaust shop to pull the o2 sensor, and stick the one old one in I removed, so I can drive it home.

HTC DNA, Williamsburg, VA

Butta!

[danewilson77]

So...I went down to get post FSM alignment done today...performed by Porkchop, and he had the O2 sensor out in about 15 minutes. he used a real torch, a long handle breaker bar, and a pry bar to apply outward pressure while loosening. Needless to say...the car being lifted and having the prybar immensely helped.

Old Vs. New
http://i1015.photobucket.com/albums/af278/nicee46/Maintenance%20and%20Misc/IMAG0603.jpg (http://s1015.photobucket.com/user/nicee46/media/Maintenance%20and%20Misc/IMAG0603.jpg.html)

So....I drove it home....sounding like a Honda with a fart can and then attempted to put the new one in. Not gonna happen. Threads in bung were pretty tore up from the abuse. Hmmm...need something to chase the threads.....

http://i1015.photobucket.com/albums/af278/nicee46/Maintenance%20and%20Misc/8e0b728a-b448-40b7-b9c0-47b0008d87d9.jpg (http://s1015.photobucket.com/user/nicee46/media/Maintenance%20and%20Misc/8e0b728a-b448-40b7-b9c0-47b0008d87d9.jpg.html)

Did not know Spark plug threads were identical to O2 sensor threads. With a little effort (3 hours), I was able to chase (manufacture new threads) the threads and install the O2 sensor.

Because Daily Driver.

http://i1015.photobucket.com/albums/af278/nicee46/Maintenance%20and%20Misc/8b85a8c2-3abc-41b0-ad4c-6ec47c2cb7d6.jpg (http://s1015.photobucket.com/user/nicee46/media/Maintenance%20and%20Misc/8b85a8c2-3abc-41b0-ad4c-6ec47c2cb7d6.jpg.html)

10 more Hp :shifty

[WOLFN8TR]

GEEZ...What a Nightmare!! :eyetwitch

[kayger12]

Way to stick with it, DW.

Glad she's finally squared away.

Sent from my kick-A Galaxy S3

[danewilson77]

Thanks for the support fella's.

HTC DNA, Williamsburg, VA

[Hornung418]

Glad it's done.

From a GS3, this was sent.

[danewilson77]

Glad it's done.

From a GS3, this was sent.

No shit. Thanks Justin.

HTC DNA, Williamsburg, VA

[jgt_zhp]

And here I thought I was the only one that kind of shite happens to. I can only imagine how many new words the neighbor kids around here would learn if I was subjected to that.

[Avetiso]

Was this the first time these sensors were swapped? If they are so hard to get out at high mileage, perhaps it is prudent to get them out and anti-seize them as a preventative maintenance measure. Unless it has nothing to do with mileage and is dependent on the age of the car.

[danewilson77]

Yes. First time post cats were done. New ones come "pre-lubed" with anti-seize. At least that's the way Bosch's come.

Idk. I heard absolute horror stories from the guys at the shop, so it's not just BMW.

But I surely could have help my situation more by starting with heat from the get go.

HTC DNA, Williamsburg, VA

[BCS_ZHP]

Don't think anti-seize would help. The temps those O2 sensors see is incredible because they are right next to the cats. And at higher miles with all the thermal cycling the metal just kind of welds itself together. Think the key Dane provided was having it in the air with better access and room to apply heat & a breaker bar to gain leverage makes it all work.

Way to stick with it Dane, sure there were several periods of cussed like a salty sailor (pun intended).

[danewilson77]

Don't think anti-seize would help. The temps those O2 sensors see is incredible because they are right next to the cats. And at higher miles with all the thermal cycling the metal just kind of welds itself together. Think the key Dane provided was having it in the air with better access and room to apply a breaker bar to gain leverage makes it all work.

Way to stick with it Dane, sure there were several periods of cussed like a salty sailor (pun intended).

Yeah.... Thanks Bruce. It was pretty insane being under there another 3 today, but I'm glad it's done. Now I can move on to my aesthetic mods.

HTC DNA, Williamsburg, VA

[LivesNearCostco]

Dane, what did Pork Chop use on the end of the breaker bar, deep socket? Broken bolt remover? On your CarQuest thread chaser, are both of those parts used for a standard O2/spark plug thread, or are there two parts for two different size spark plugs?

[danewilson77]

He used a 22mm socket, with a 24" breaker bar. My 22mm just spun, most likely due to the angle/space I had. As he loosened the O2 sensor, he also had to "wedge in" a pry bar and pry out. he was using both hands to remove it. I hope that makes sense.

EDIT: repeating wedge is not my fault and is uneditable.

[echo46]

Whoa, just read this nightmare. Glad you got that bastard out. Now I'm scared, very scared to get mine out.

[danewilson77]

Whoa, just read this nightmare. Glad you got that bastard out. Now I'm scared, very scared to get mine out.

Start many days in advance with PB Blaster, then use heat and PB Blaster on day of removal.

Use a breaker bar and O2 sensor socket, and I think you will be fine.

[LivesNearCostco]

Dane, that does make sense. Thanks!