Can't get the cotton-pickin' oxygen sensor out!

[chimay]

I've been trying to replace the oxygen sensor on a 1990 325i. The sensor is conveniently placed right off the manifold where you can access it from the hood.

So first I tried an adjustable wrench, and pulled and pulled to the left, but couldn't get it off, then I bought a regular non-adjustable wrench, but still no luck. So I got some WD-40 and sprayed some on it -- twice and waited a few hours for it to do it's work. Still no dice. Then I went and got an oxygen sensor tool which contains an attachment for a ratchet wrench that fits right over the nut on the oxygen sensor. That should've done the trick, but Still no luck!

Okay, so now I'm wondering -- am I turning this thing the right way? I'm turning left -- counterclockwise, towards the passenger compartment. That should be the right direction, right? If I'm turning the wrong direction that would explain everything, but it seems to me that almost every nut loosens counterclockwise. (Hmm, now that I think of it, I think I'll have a look at the threads on the new sensor to verify this.)

Maybe it's time to take it to a shop, but it seems kind of silly just for an oxygen sensor that I should be able to change myself.

[chimay]

I've come to the conclusion that the oxygen sensor is probably seized. The car has 130K miles and possibly the sensor hasn't been changed in quite a long while, if ever. I guess it will have to be taken to a shop, unless anyone has any other ideas. I've applied liberal amounts of WD-40 but that hasn't helped.

[Mark E M]

Ok, the OX sensor is baisicly junk any way, so if you bust off the top piece and the wires there is no loss. Whay happens is from repeated hot and cold cycles it has frozen in place. Heat the pipe around where it threads in , with a propane torch, will take about ten min. to heat up. Then spray the OX sensor with the WD-40 right at the threads, use the tiny plastic nozzle supplied with the WD to direct the spray right at the threads. Quickly put the wrench or socket on the OX sensor and try to remove. As soon as you get it to turn a little, rock it back and forth, and spray again.. You may need to heat it a couple of times to get it out. But once it comes loose the hard part is done. Once the sensor is out, coat the new ox sensor threads with anti-seize, do NOT get this on the ox sensor cover that goes into the exhaust pipe. Carefully thread in,avoiding cross threading, and hook up the wires and VOILA!! Your done. Hpoe this helps. Mark.

[ghight]

I didn't have time to read the other replies, but this works for me on old sensors: spray some/lightly WD-40 on the base of the sensor, run the engine for 3 min, use something metal and rap on the pipe with a wrench several times then trie removing. That usually loosens rusted parts. Lube, heat and a couple of well-placed whacks.

[chimay]

I haven't tried running the engine first, as it seemed to me that the parts would expand with heat and become even harder to remove, but it sounds like you really need the heat to free a seized part.

WD-40 hasn't done the job so far. I noticed that there are some other products on the market that are supposed to be more suited to this specific purpose.

Here's a list of ones I've read about:


"Loosen Up™ Penetrating Oil
http://www.wellworthproducts.com/pro...enetrants.html

Special formulation enables Loosen Up to creep better than ordinary products. Penetrates through rust, grease and dirt to loosen seized parts. Even under the most extreme conditions, special additives guarantee constant lubrication and resistance to high temperature breakdown."


PB Blaster
http://www.pbblaster.com/store/


Liquid Wrench Super penetrant
http://www.gunk.com/item_asp/L104.asp


Marvel Mystery Oil

[daniel 61]

Originally Posted by ghight

I didn't have time to read the other replies, but this works for me on old sensors: spray some/lightly WD-40 on the base of the sensor, run the engine for 3 min, use something metal and rap on the pipe with a wrench several times then trie removing. That usually loosens rusted parts. Lube, heat and a couple of well-placed whacks.

try any Coca~cola product , this disolve anything !!!.

[ghight]

Originally Posted by daniel 61

try any Coca~cola product , this disolve anything !!!.

LOL!!! sorry, the coke trick works for desolving acids like on the battery and posts. I don't think it will penatrate rusted metal. but you never know! You could have a sollution (no pun intended) there!