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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Technical Forums > Mechanical Maintenance: Break-in / Oil & Fluids / Servicing / Warranty > e92 N54 is losing coolant fast, but no sign of leak.



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      08-22-2019, 04:39 PM   #1
lukemcmullen45
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e92 N54 is losing coolant fast, but no sign of leak.

About a month ago I got a low coolant warning light, and when the engine cooled off I checked, and it was low. I filled it up to the top with distilled water, and everything was fine from there. After a couple of days it went low again so I topped it off with distilled water yet again. I noticed over the last month that it was only when I used my AC that it went low, and where I am itís 100į+ all day and Iím of course going to use my AC. When the engine is running I notice no signs of leaks and thereís no puddled coolant anywhere. My guess was that because I kept filling it with distilled water that it was boiling and then steaming and evaporating. So I did a partial coolant flush with BMW coolant, did everything right and bled the system properly. For about 3 days I had no problems until yesterday my low coolant light came on again, had no choice but to top it with distilled water. Now every morning I check my coolant reservoir and itís always at least a little bit too low so I fill it to the correct level. Any guesses what this could be?
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      08-22-2019, 04:55 PM   #2
lukemcmullen45
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Also I should add that when I drained the coolant it was pretty much clear because of how much I had to top it off with distilled water. I probably went through 5 or 6 gallons of distilled water in the span of a month.
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      08-24-2019, 06:36 AM   #3
insanesam
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Quote:
Originally Posted by lukemcmullen45 View Post
About a month ago I got a low coolant warning light, and when the engine cooled off I checked, and it was low. I filled it up to the top with distilled water, and everything was fine from there. After a couple of days it went low again so I topped it off with distilled water yet again. I noticed over the last month that it was only when I used my AC that it went low, and where I am itís 100į+ all day and Iím of course going to use my AC. When the engine is running I notice no signs of leaks and thereís no puddled coolant anywhere. My guess was that because I kept filling it with distilled water that it was boiling and then steaming and evaporating. So I did a partial coolant flush with BMW coolant, did everything right and bled the system properly. For about 3 days I had no problems until yesterday my low coolant light came on again, had no choice but to top it with distilled water. Now every morning I check my coolant reservoir and itís always at least a little bit too low so I fill it to the correct level. Any guesses what this could be?
Had the same issue. Replacing coolant expansion tank with new cap fixed it. I still lose coolant but i think within "normal" ranges
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      08-26-2019, 03:31 PM   #4
lukemcmullen45
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Quote:
Originally Posted by insanesam View Post
Had the same issue. Replacing coolant expansion tank with new cap fixed it. I still lose coolant but i think within "normal" ranges
What do you mean by normal ranges?
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      08-26-2019, 06:03 PM   #5
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Quote:
Originally Posted by lukemcmullen45 View Post
What do you mean by normal ranges?
Prior to tank change the low coolant warning light would come on a few days after topping it up. Post tank change the light has never come on and I would need to top-up 50-100ml every month
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      08-26-2019, 07:38 PM   #6
DerekGates
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Quote:
Originally Posted by insanesam View Post
Had the same issue. Replacing coolant expansion tank with new cap fixed it. I still lose coolant but i think within "normal" ranges
This is exactly what I went through last weekend! Mysterious coolant loss, fixed by coolant tank/cap.

I will say, without hose 'clamp' pliers (to stop coolant flow) you WILL make a mess. Not the end of the world, but be prepared for some wetness!
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      11-07-2019, 05:54 PM   #7
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Any idea about a leak that only shows when the engine is warm? My E90 does not leak when pressure tested, but will loose all coolant after driving for 10-20min when the engine is at normal temp.

Radiator, hoses and expansion cap have been replaced recently!
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      12-25-2019, 03:41 PM   #8
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Loosing coolant fast

Im completely new on this site and i too have same problem so can anyone help me? My car looses coolant slowly while im not driving it. Looses it quicker when i am driving it. Has slight oil in tail pipe and on start up slight blue smoke from tail pipe. It also has smoke coming from front radiator area after driving for a while. Bmw 335d 2010 e92. it has ben remapped also. Not by me. Thanks
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      12-29-2019, 06:54 PM   #9
niteshadesc2
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@yourtoastm8 - Have you checked your oil levels? Is it dropping as well? Checked your oil to see if you have coolant contaminating it? Checked your coolant to see if there is oil in it?
I'm thinking head gasket(?) - any check engine codes?

Niteshade
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