RM European Auto Parts
Results 1 to 7 of 7

Thread: Assumed Coolant Leak in e90, Best way to test?

  1. #1
    Join Date
    May 2016
    Location
    New England
    Posts
    26
    My Cars
    2007 BMW 328xi

    Assumed Coolant Leak in e90, Best way to test?

    I have a 2007 328xi, with ~66k miles.

    I drive it fairly irregularly, a couple times a week. I drove it about 130 miles on Saturday, with no issues that I noticed. No warnings, etc.

    On Wednesday, it snowed, and I share a driveway with my neighbors, so I had to move my car to clean around it. I left the car running/warming while I cleaned it off (probably ~10min). When I was finished I put my car back and noticed a small amount of coolant in the snow. The next day (after the car had cooled down) I checked the coolant reservoir and it was low. The stick was not poking out at all (still visible, the top was about flush with the top of the reservoir).

    I added coolant to the reservoir last night and put a couple pieces of cardboard under the car. Should I run the bleed procedure (with the holding the gas pedal in for 10 seconds, etc), and check for leaks again? Sadly I'm in an apartment and don't have a jack or ramps, so my best option is just to take it somewhere, but I wanted to make sure it wasn't an obvious hose before I did that.

    Some info:
    -I did the water pump and thermostat over the summer. I haven't had any issues since then.
    -A BMW mechanic did the reservoir sensor not too long ago, so I have some faith that that's working correctly, and it makes me guess that the leak isn't related to my changing the pump/stat because I figure it would have given me a low-coolant warning or overheated by now.
    -I used blue BMW coolant, while the stuff that leaked was more of a neon greenish color. Any ideas on the issue here? I had some left over from the second gallon I bought when I did the water pump, and I poured it in some snow (I cleaned it up, I promise) and it was definitely a different color.

  2. #2
    Join Date
    Mar 2003
    Location
    St. Joseph, Mo.
    Posts
    3,000
    My Cars
    95 m3+, 03 ZHP, Mk4 Tdi
    hmm - did you do a flush when you did the water pump and tstat? was the coolant that came out then blue or green?

    regardless - if i suspect a leak in the cooling system and it's not obviously visible i hook up a pressure tester to the system, pressurize, and look for leaks.
    '95 325iS - auto to manual swap done!

  3. #3
    Join Date
    Jun 2002
    Location
    Aberdeen, NC (yes, again)
    Posts
    23,672
    My Cars
    E39M5, E500 4WD
    Before you did the water pump, did the car have green coolant? Often the A/C system has dye in it, which is bright neon green.

    There's a small plastic pipe, which connects your radiator to your expansion tank. It's hard to see, but it runs over the top of the fan unit, pretty much hidden. It's a terribly weak P.O.S., and rots and breaks and leaks at the slightest provocation.....or none at all. part number 7 here:

    http://www.realoem.com/bmw/enUS/show...diagId=17_0350

    Look for signs of splitting, corrosion, swelling or leakage there. Do not touch it until you have the replacement in hand, if you see that's what's leaking.

    Of course, I fully agree with shadowpuck, that you immediately deal with any cooling system leaks by having a pressure test done, unless of course you can find and replace any obviously leaking item yourself.

    Chris Powell
    Racer and Instructor since, well. decades, ok?
    Master Auto Tech, owner of German Motors of Aberdeen
    BMWCCA 274412
    German Motors is hiring ! https://www.bimmerforums.com/forum/s...1#post30831471

  4. #4
    Join Date
    May 2016
    Location
    New England
    Posts
    26
    My Cars
    2007 BMW 328xi
    Thanks you guys. As usual you all set me on the straight and narrow. I didn't do a complete flush of the coolant when I did the water pump, so I wouldn't be surprised if that's where the color came from. So much drained when doing the pump I sort of figured that the blue coolant I added would be the dominant color. Probably a red herring at this point.

    Sounds like a pressure test is my first step, along with some finger crossing that it's the pipe that you mention Chris, as that seems like the best case scenario.

  5. #5
    Join Date
    May 2016
    Location
    New England
    Posts
    26
    My Cars
    2007 BMW 328xi
    Well, I pressure tested and didn't see any leaks, so I took it for a drive, and when I got back there was definitely liquid in the engine bay.

    I still can't figure out where it originates, but it looked like it's coming from the reservoir, though it seems like it's in an odd place. The left side of the rim was wet, and the right side of the rim was bone dry. It looked like it was dripping down from the reservoir.

    leakandblock.png
    Last edited by nulset; 03-20-2018 at 08:26 PM.

  6. #6
    Join Date
    Mar 2003
    Location
    St. Joseph, Mo.
    Posts
    3,000
    My Cars
    95 m3+, 03 ZHP, Mk4 Tdi
    was the cooling system full when you did the test? what pressure did you set it at? how long did you leave it pressurized?
    '95 325iS - auto to manual swap done!

  7. #7
    Join Date
    May 2016
    Location
    New England
    Posts
    26
    My Cars
    2007 BMW 328xi
    I followed Pelican Part's guide, essentially; 1.5 Bar (~22 PSI), started looking for leaks after 2 minutes at pressure. The reservoir was full when I pressurized. I didn't notice it losing pressure, but I admit I was focusing more on searching for a leak.

Similar Threads

  1. Best way to test DK motor flap operation
    By CaifanSC in forum 8 Series (E31)
    Replies: 9
    Last Post: 09-17-2015, 03:41 AM
  2. Best way to test speed sensor circuit?
    By bmwlovr in forum 1996 - 2003 (E39)
    Replies: 5
    Last Post: 04-29-2015, 02:49 AM
  3. Replies: 3
    Last Post: 04-12-2008, 11:36 PM
  4. Best way to test?
    By jchristians in forum 1975 - 1983 (E21)
    Replies: 5
    Last Post: 01-03-2008, 02:16 PM
  5. Best way to test the maf sensor? help needed
    By Alpay71 in forum 1991 - 1999 (E36)
    Replies: 7
    Last Post: 04-15-2007, 05:09 PM

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
  •