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Thread: Random Coolant Leak

  1. #1
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    Random Coolant Leak

    2001 740. I parked my car last night but came back to it two hours later and noticed a big puddle of coolant under the engine and around my right tire. What could of caused this? a lose or broken hose?
    Last edited by geoprz; 07-20-2018 at 07:32 PM.

  2. #2
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    Open the hood and inspect the cooling system,
    photo would help us-help you.

  3. #3
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    Front right tire can also be indicative of a washer fluid leak. Also blue and thin like the BMW coolant.
    '98 740il | 9/97 build | schwarz 2 | sandbeige | 5AT | 270k
    '04 330i ZHP sedan | Mystic blue | Alcantara | 6MT | 120k
    '00 540i sport | Titanium silver | Black | 5AT | 152k
    '85 Mustang GT convertible | Medium charcoal metallic | Gray | 5MT | 216k | one owner, all original

    mods: m-pars | Bilsteins & B&G springs | ValentineOne | StealthOne
    retrofits: full nav | MKIV | bluetooth TCU | BM53 w/ AUX input | video module w/ AV input & backup cam | oem sirius xm | xenon | shades | PDC | rain sensor | BMW DWS TPMS | lighted door handles | front seat heaters | heated steering wheel | euro rear fog lights | ski pass | folding mirrors


  4. #4
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    For sure it’s not washer fluid. It’s coolant. Attached are pictures of the coolant spill. The picture with the car out the way shows all the stains/spots that were never in that spot before. Took the rad fill cap off and saw very little coolant deep down. I can’t say where the levels were before for certain. So i turned on the car today and let it idle. No leaking or anything. Drove it around for a bit and the engine temp gauged stayed right in the middle as usual. Car was on for minimum 30 min. Turned a/c full blast and the temp gauge remained. What am i not thinking of here? Next step is to pick up coolant and fill it up and see if it starts to leak again.
    Attached Images Attached Images
    Last edited by geoprz; 07-20-2018 at 07:32 PM.

  5. #5
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    Top off to the correct level in the morning,
    on a cold engine, don't overfill.

  6. #6
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    I will do that. But then what answers are we looking for? The float gauge in the coolant rad opening is showing me low coolant. I went back to my car now and notice a slow drop leak of coolant again. This is after the drive. It was not leaking before the drive all day or over night...

  7. #7
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    Because the pressure builds on a hot engine after a drive.
    Try to carefully observe where the coolant droplets are emitting from.

  8. #8
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    That’s hard to determine because of the plastic covers all underneath. The droplets are coming from right in the center under the engine but that doesn’t mean much since the plastic under body is covering everything and the leak could be just draining there at the leaky point

  9. #9
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    Pull the lower cover, give it a short drive, park it and get underneath. A good light will probably find the trail.
    Water pump or lower hose(s)....

  10. #10
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    Yes unfortunately, someone,
    be it yourself, a friend, family member,
    or auto mechanic is going to have to pull that cover.

  11. #11
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    Not sure how much you poked around under the hood, but grab a bright flashlight and a telescoping mirror and with the engine running, look around for leaking coolant. You can usually spot it if you know where to look.

    Here's the easy way to start...
    Open the hood and look at the plastic belly pan from up above. If you see that it is wet at the front near the radiator, see #1.
    If that area appears dry, move on to #2.
    If that is good, move on to #3.

    1. The major sources you can see right in front that would cause the front of the belly pan to be wet: radiator and connections, expansion tank and connections, water pump, transmission cooler, water cooled alternator. You can also peek around on top of the water pump to see if there is coolant there coming out of the coolant pipes that run across the valley.

    2. Other sources you can see from the rear: heater hoses, aux water pump

    3. Other sources you can see from the rear under the intake after removing the plastic intake cover: rear of valley pan, rear coolant pipe o-rings, rear coolant accumulator (mirror will help).

    It has to be one of those because that's all there is for coolant sources other than the coolant plate on the back of the block above the rear main.
    '98 740il | 9/97 build | schwarz 2 | sandbeige | 5AT | 270k
    '04 330i ZHP sedan | Mystic blue | Alcantara | 6MT | 120k
    '00 540i sport | Titanium silver | Black | 5AT | 152k
    '85 Mustang GT convertible | Medium charcoal metallic | Gray | 5MT | 216k | one owner, all original

    mods: m-pars | Bilsteins & B&G springs | ValentineOne | StealthOne
    retrofits: full nav | MKIV | bluetooth TCU | BM53 w/ AUX input | video module w/ AV input & backup cam | oem sirius xm | xenon | shades | PDC | rain sensor | BMW DWS TPMS | lighted door handles | front seat heaters | heated steering wheel | euro rear fog lights | ski pass | folding mirrors


  12. #12
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    Thank you very much for the advice and suggestions. Im dealing with a concussion so unfortunately i can’t do physical work on it myself. So i’m just going to drop it off at the bmw dealership. My friend works there and i’ll get a deal on parts and labour. Plus my seven has 70k miles on it and i think it’s time for some additional maintenance check ups. fluids check and tranny flush etc should be done this time around and whatever else the mechanic recommends. Thanks again.

  13. #13
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    So, I may have jumped the gun when i assumed my problem was a coolant leak. I wanted to take the seven out for a spin today to see if i can figure out the “coolant leak”. But within seconds of driving, my steering wheel felt really stiff. So i now assume it was a power steering leak this entire time and it makes sense now but the fluid levels are good.

    I did replace my power steering pump a few years ago. What could be another problem with the power steering leak?

  14. #14
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    The power steering hoses and stuff is on the driver's side...

    Sent from my SM-N910T3 using Tapatalk

  15. #15
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    If your power steering went stiff, you want to make sure the accessory belt is still on.

    Here's a possible scenario...
    If the water pump seal starts leaking, it'll start dripping coolant down onto the belly pan. That coolant can turn to a faster leak and leave a puddle like you are experiencing. As this coolant leaks past the seal it gets into the bearing and can ruin the grease. The bearing will in turn eat itself in time and can seize, thus taking out the accessory belt, leading to no power steering and no alternator.

    That is of course one scenario that could link a coolant leak with your recent power steering issue.
    '98 740il | 9/97 build | schwarz 2 | sandbeige | 5AT | 270k
    '04 330i ZHP sedan | Mystic blue | Alcantara | 6MT | 120k
    '00 540i sport | Titanium silver | Black | 5AT | 152k
    '85 Mustang GT convertible | Medium charcoal metallic | Gray | 5MT | 216k | one owner, all original

    mods: m-pars | Bilsteins & B&G springs | ValentineOne | StealthOne
    retrofits: full nav | MKIV | bluetooth TCU | BM53 w/ AUX input | video module w/ AV input & backup cam | oem sirius xm | xenon | shades | PDC | rain sensor | BMW DWS TPMS | lighted door handles | front seat heaters | heated steering wheel | euro rear fog lights | ski pass | folding mirrors


  16. #16
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    Quote Originally Posted by racer2086 View Post
    If your power steering went stiff, you want to make sure the accessory belt is still on.

    Here's a possible scenario...
    If the water pump seal starts leaking, it'll start dripping coolant down onto the belly pan. That coolant can turn to a faster leak and leave a puddle like you are experiencing. As this coolant leaks past the seal it gets into the bearing and can ruin the grease. The bearing will in turn eat itself in time and can seize, thus taking out the accessory belt, leading to no power steering and no alternator.

    That is of course one scenario that could link a coolant leak with your recent power steering issue.
    This racer guy is one smart cookie!

  17. #17
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    so we are going to act like power steering isn't a red oil and so so so so so different from coolant.

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