Page 1 of 2 12 LastLast
Results 1 to 25 of 32

Thread: DIY: How to fix a leaky temp sensor o-ring for 59 cents

  1. #1
    Join Date
    Jun 2004
    Location
    Tulsa, OK
    Posts
    106
    My Cars
    '98 M3/4/5 WEE09113

    DIY: How to fix a leaky temp sensor o-ring for 59 cents

    My '05 325i (~80k miles) recently began dribbling coolant from the temp sensor housing on top of the lower coolant hose. I did a Google search and found some good information that allowed me to fix the leak *without* buying a whole new sensor from BMW, which is the only way to get an o-ring from them! Total time to fix was less than 15 minutes.

    1. Here's a pic of the leaking sensor, taken from underneath the car. I'd already pulled the car up onto ramps in the front, and removed the lower tray. Sorry for the general crappiness, but I only had my iPhone handy.


    2. From the top side, I used a flat-blade screwdriver to release the metal retainer clip and unplug the sensor. Then I squeezed the sensor release and pulled it out of the housing. NOTE: I did this on a cold motor, and lost very, very little coolant.

    3. I used a small flathead driver to carefully pry off the the old green o-ring. I found dimensions on another site that equated to a #31 o-ring, which I found at Ace hardware for $0.59.


    4. I popped the new o-ring on the sensor, re-seated it in the housing (it snapped right in for me), and hooked it back up. TIP: It might be obvious, but it's much easier to position the wire retainer clip on the sensor end BEFORE you plug it in... Otherwise you'll end up cussing and dropping it 5-10 times in the process. AMHIK. Anyway, I fired the car up, and watched the sensor for any sign of leaks as it came up to temp. No problems at all!


    So, a pretty cheap and simple solution to what seems to be a common problem. Hope it helps!
    JJ
    -----------------------------
    Current:
    '98 M3/4/5

    Past:
    '05 325i Sport
    '97 328i Sport
    '87 635 CSi
    '76 2002
    '72 2002

  2. #2
    Join Date
    Sep 2007
    Location
    MD
    Posts
    257
    My Cars
    BMW 328Ci
    Great post, I went through that trouble after replacing the whole cooling system.

    But at the dealer, they only sell the sensor as a complete part...not the o-ring, how did u find the exact size at ACE? Lower hose sensor is 23 dollars not too bad.
    High Mileage 325,xxx and counting...
    BMW runs in the family
    3-Series my whole life
    e30 325i / e36 328is /
    e46 323i / 328Ci / 330Ci / 335i E92 / E46 M3



  3. #3
    Join Date
    Aug 2009
    Location
    MIDWEST,U.S.A.
    Posts
    1,015
    My Cars
    2004 -Z4-2.5i,96-Z3-1.9L

    Thumbs up

    okartguy-THANKS, it sure did help me! edit: #31 o-ring also found at Home Depot-part#96745 sold in pak of 10 for $1.79
    Last edited by STEALTHYZ4; 11-27-2009 at 01:06 AM.

  4. #4
    Join Date
    Oct 2007
    Location
    Charlotte, NC
    Posts
    218
    My Cars
    06 Z4Mc,291 318is,98 M3s
    Excellent write up! thanks

  5. #5
    Join Date
    Jul 2008
    Location
    Norman, OK
    Posts
    410
    My Cars
    2005 325i
    to the OP, or anyone else who has removed the temperature sensor:
    I am trying to do this fix as I have a slow leak at the sensor. I can get the clip off and unplug it no problem. However, when I try to pull the sensor from the socket it is not budging. I am squeezing the prongs and pulling straight up. I tried this with my bare hands, a pair of pliers and a vice-grips. With the tools its hard to pull up because of interference from the A/C lines running across. What I seem to need is like a stubby pliers or much stronger fingers - hey, I have a desk job, I'm not a cow milker. Should it be this difficult, any ideas? I'd rather not take the entire lower radiator hose off, but its beginning to look like that is my next option.
    Fahrer von Alpinweiß

  6. #6
    Join Date
    Dec 2009
    Location
    Austin, TX
    Posts
    31
    My Cars
    None
    Thanks for the tip OP - saved me the price of a sensor, and now I have 9 spares

    Quote Originally Posted by kbok View Post
    to the OP, or anyone else who has removed the temperature sensor:
    I am trying to do this fix as I have a slow leak at the sensor. I can get the clip off and unplug it no problem. However, when I try to pull the sensor from the socket it is not budging. I am squeezing the prongs and pulling straight up. I tried this with my bare hands, a pair of pliers and a vice-grips. With the tools its hard to pull up because of interference from the A/C lines running across. What I seem to need is like a stubby pliers or much stronger fingers - hey, I have a desk job, I'm not a cow milker. Should it be this difficult, any ideas? I'd rather not take the entire lower radiator hose off, but its beginning to look like that is my next option.
    It shouldn't be that hard. Mine pulled right out. You might try pushing down on it first, or wiggle it. Can you get at it from under the car and push up with a flat blade screwdriver?

  7. #7
    Join Date
    Feb 2009
    Location
    Parlin,New Jersey,USA
    Posts
    10
    My Cars
    2003 330i

    Question about this repair

    It was bitter cold in NJ yesterday (about 14F) and when I left work to go into my car I noticed a small puddle of antifreeze in the front/center of my car. Do you think that this might be a result of a leaking O-ring? Please let me know. It looked like about 3 or 4 ounces of fluid.

  8. #8
    Join Date
    Dec 2009
    Location
    Austin, TX
    Posts
    31
    My Cars
    None
    Quote Originally Posted by dinot71 View Post
    It was bitter cold in NJ yesterday (about 14F) and when I left work to go into my car I noticed a small puddle of antifreeze in the front/center of my car. Do you think that this might be a result of a leaking O-ring? Please let me know. It looked like about 3 or 4 ounces of fluid.
    That sounds about right. It was pretty easy to diagnose and change so it would be a good place to start.

  9. #9
    Join Date
    Feb 2009
    Location
    Parlin,New Jersey,USA
    Posts
    10
    My Cars
    2003 330i
    Quote Originally Posted by jmoberley View Post
    That sounds about right. It was pretty easy to diagnose and change so it would be a good place to start.
    I am going to check it tomorrow afternoon. I guess that sensor is near the top of the radiator, right? DO you know where the expansion tank is located? I read that that could also be causing my coolant leak.

  10. #10
    Join Date
    Jan 2009
    Location
    Williamsburg, VA USA
    Posts
    22,932
    My Cars
    2004 ZHP 6MT
    This should help out as it seems to come up every now and then. Great job dude!!!

    by Dane Wilson, on Flickr

  11. #11
    Join Date
    Aug 2006
    Location
    Edmonton, Alberta, Canada
    Posts
    1
    My Cars
    325is, 328I
    For a short term fix until you get the right o-ring.

    Take out the o-ring carefully, get some faucet teflon tape and wrap it around the grove where the o-ring usually sit. I wrapped 3 full turns. Put the old o-ring back. I've mine for a week now with out leakage.

  12. #12
    Join Date
    Oct 2010
    Location
    Belleville, IL
    Posts
    1
    My Cars
    2002 BMW 330i
    Yep, worked like a champ. Only took 5 minutes to replace...

  13. #13
    Join Date
    Feb 2010
    Location
    Orlando, Fl
    Posts
    66
    My Cars
    2003 E46 Sedan
    Finally, someone actually posting a DIY in this section instead of asking a question which both the Sticky and the Section description explain.

    Thanks

  14. #14
    Join Date
    Dec 2004
    Location
    Louisville
    Posts
    4,625
    My Cars
    e30, X3, Z3... K1100rs
    I used this thread to fix my car today. I had the O-Ring from a left over kit for a R-134 conversion.

    Thanks!


    Remember: Your life can be extinguished in ONE stupid moment. No one is invincible....

  15. #15
    Join Date
    Aug 2009
    Location
    Chicago, IL
    Posts
    493
    My Cars
    04 325iA, 95 525 5sp
    This thread saved me this morning. Changed the oil in the wife's E46 today and gasped when I saw the coolant leak. Quick trip to Ace and we're back in business! THANK YOU. I always poke around in the engine bay when doing oil changes, so I'm glad I did.

  16. #16
    Join Date
    Jul 2010
    Location
    houston, tx
    Posts
    3
    My Cars
    03 325ci vert
    Quote Originally Posted by bmw328ciwa View Post
    Great post, I went through that trouble after replacing the whole cooling system.

    But at the dealer, they only sell the sensor as a complete part...not the o-ring, how did u find the exact size at ACE? Lower hose sensor is 23 dollars not too bad.
    Same here, i had the entire cooling system replaced and then started leaking from the sensor. Looks like an easy fix, thanks for the write up.

  17. #17
    Join Date
    Jan 2011
    Location
    Tacoma, WA, USA
    Posts
    1,213
    My Cars
    2001 325i, 2002 X5 3.0i
    I had to do a similar emergency o-ring repair on my car, one of the o-rings on the upper radiator hose connection to the expansion tank got pinched or otherwise damaged during reinstallation. All I did, though, was soaked it in brake fluid to cause it to expand until I could get a replacement.

  18. #18
    Join Date
    Feb 2007
    Location
    Delanco, NJ
    Posts
    374
    My Cars
    Fern Green E46 coupe
    Thank you very much for this! I have a 6-series that uses the same exact temp sensor that was also leaking on my car. Very easy to do from the top on the E63 without the use of any tools!

    BMW F01 Alpine White 750i xDrive (w/Oyster Interior) - PICS
    BMW E63 Jet Black 645ci - SOLD
    BMW E46 Fern Green 323ci - SOLD

  19. #19
    Join Date
    Jan 2010
    Location
    LaPorte, IN
    Posts
    19
    My Cars
    2005 325xi
    okartguy, thanks for the write-up. I will be replacing the oring over the holiday. Again, thanks for taking the time out to write the post.

  20. #20
    Join Date
    Jun 2008
    Location
    Mt. Airy< MD
    Posts
    7
    My Cars
    02 330ci, 84 318i

    O Ring

    Happy New Years.

    Just did a Temp Sensor ORing replacement using the Dorman #31 ORing.

    Didn't Work.

    It is still leaking and guess I need a proper "Green" BMW O Ring.
    Called, Texted and sent Email to local dealer who stated: "Can't Buy The O Ring Seperately".
    I believe I saw someone post a "BMW" Part Number for the Green O Ring seperately and/or some one who sells them.

    Thanks In Advance
    Doc

  21. #21
    Join Date
    May 2011
    Location
    Bellingham, WA, USA
    Posts
    1
    My Cars
    2004 325Xi
    BMW part # 13621743299

  22. #22
    Join Date
    Jun 2008
    Location
    Mt. Airy< MD
    Posts
    7
    My Cars
    02 330ci, 84 318i

    Thanks

    Forgot I Found One

  23. #23
    Join Date
    Aug 2014
    Location
    Las Vegas
    Posts
    1
    My Cars
    2006 325i
    This thread was awesome. Thanks! If anyone else is having issues removing it (stuck). Just grab a flathead screwdriver, try to get it under the sensor and just twist it while pressing on the 2 tabs. Theres no reason to get under the car.

  24. #24
    Join Date
    Sep 2014
    Location
    CHICAGO, IL
    Posts
    1
    My Cars
    2000 BMW 323 CI

    Problems after o ring replacement

    Quote Originally Posted by ShadowPilot View Post
    This thread was awesome. Thanks! If anyone else is having issues removing it (stuck). Just grab a flathead screwdriver, try to get it under the sensor and just twist it while pressing on the 2 tabs. Theres no reason to get under the car.
    So, I installed a #31 o-ring, 9/16 od-5/16 id-1/8 thick, as a replacement on the coollant temp sensor, ultimately fixing the leak and turning off the SES light on the dash. All great!, however, now my temp guage shows max, my DSC light is on (meaning traction control off), my battery and oil lights are on as well, and also my emergency brake light is on--- all on the dash....I know your probably thinking the same thing, why the heck would any of those come on besides maybe the temp guage being maxed to hot? well, I figured maybe now that the whole coolant temp sensor needs to be replaced and that is what is causing the problems...and of course now i cant get the sensor out which is stuck with the new o ring....though it is still stuck i continued to think this over and thought maybe it's not a bad sensor as even before o ring replacement when it was still leaking, the sensor and guage seemed to be working fine...starting out cold and then sitting at 12 0'clock on the gauge once engine heated up...it was just the leak that needed fixing was my thinking and why i just did the o-ring replacement. I also bled the radiator system at the bleed cap to see if maybe air in the system was the reason the temp guage is all the way hot...nope. i then tried resetting the battery...nope, that didnt work either... Can anyone on here tell me why all of this might be happening and what i can do to fix the issue?

    Sincerely and Thank You in advance,

    Nick

  25. #25
    Join Date
    Jul 2007
    Location
    Parsippany, NJ, USA
    Posts
    314
    My Cars
    328I, 1999.
    Awesome thread... I followed leak in my car, and seems like it is the temp sensor. I have 2007 530I, and the part number for the temp sensor is diff (its 13621433077).

    Few questions...How would you find the right o ring? Is it only dimensions, or also the material (it has to withstand heat and coolant)?

    Thanks.
    umermariner

Page 1 of 2 12 LastLast

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •