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Old 09-11-2019, 05:56 PM
CruisinginStyle CruisinginStyle is offline
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Regarding Coolant Levels and Coolant Cap on 340

Since I purchased my BMW 340 in 2016, I have been having to often "top off" the Coolant Levels on the Main Coolant Tank. I've had it checked by BMW several times-- each time they at least say they pressure test it with no findings of leaks of any sort. I do notice that the Coolant Cap is somewhat floppy-- not really sealed well. I wonder if Coolant may evaporate or spill out due to this? I was given a new Coolant Cap recently by BMW, but it is similarly floppy, with no solid seal whatsoever. Do any 340 owners have a Coolant Cap that is also floppy, not sealing well--- or are there any 340 owners who also have to often "top off" the Coolant. Interestingly, I have never had any sensor warnings. Appreciate any and all feedback...
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Old 09-11-2019, 07:09 PM
namelessman namelessman is offline
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The coolant cap on top of the coolant reservoir has an arrow that needs to line up with another arrow on the body of the reservoir, if not there will be no seal.
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Old 09-12-2019, 01:31 PM
insanecoder insanecoder is offline
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I really think one of two things is happening
1) the cap is not a tight seal or inadequate to seal the coolant under high pressure and so you have leakage/vaporization
I have evidence of dried leakage around the threads and outside
No evidence of vaporization but its very likely and over time you have drop in coolant levels

2) the same thing happening in the turbo
Coolant escapes the seals in the turbo and vaporizes or exits along w/ the exhaust
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