Coolant Leak N55

[swunder]

Hey - low coolant light came on yesterday - got home topped off with distilled water. Next day on the way to work, and to stopping by the dealer to pick up coolant (40 miles), the light came on again -- topped off before leaving work for the day and the light came back on the way home. So obviously I'd say this is a leak -- can't really tell where as I don't have a garage, its raining and I don't see anything obvious/blue in the engine bay.

My stupid question is - I should see coolant in the tank right? Its so hard to see in there even with my phone flashlight. An hour ago I topped it off again and think I saw coolant above the line, and now I just checked and it looks empty. Is it settling? Is it pouring onto the ground somewhere? I had the same issue with my mini one time (constant filling), brought it to a mechanic who checked the system and let it run for 4 straight hours without seeing a drop. Charged me nothing, sent me home and I never saw a leak again for the next year I owned it. So now I'm annoyed/concerned about a phantom coolant leak all over again.

I'm bringing the car in to the dealer tomorrow (have a warranty) but I'm half expecting them to say we couldn't find anything.

[The Wind Breezes]

There's a indicator for low and high level in the tank. You'll see it with your flashlight. There should be fluid in the tank. Your pump, or expansion tank itself may be going out. I had both break and the pump is a especially common issue.

Whatever it is, better address it soon because it will probably escalate and leave you stranded.

[CrimsonFury]

Ive also run into low coolant on my 2013 135is. Our tank is a llittle bit different if i recall from other pictures i have seen of 135i coolant tanks; there is a yellow indicator in there, the coolant line needs to be above the yellow indicator but below the max line, (there should only be a tiny amount of bmw blue coolant above the yellow indicator thing, any higher than that and you are above max.)

I found this post with a picture of tank for reference.
https://www.1addicts.com/forums/show....php?t=1079174

I had my car serviced yesterday to change out my brake fluid, and the tech noticed my coolant was low again, i put some in 4-5 months ago but i havent gotten any low coolant lights or anything. The tech pressure tested the coolant system and found no leaks, and no signs of leakage, and my garage floor is always dry. Yet in my research i found posts from people talking about how the n55 expansion tank is prone to cracking and leaking, so keep an eye out for that.

i never seen my engine temps get hotter than 240* in my daily driving (even spirited).

hope this helps.

im also curious what the dealer finds is the cause of your low coolant. It appears i have a phantom coolant leak as well; although ive heard people say the n55 "burns coolant"; where the hell would it go?

heres a thread, lots of n55 owners dealing with vanishing coolant.

"Mine did the same thing not long ago. The coolant expansion tank was the problem. It was leaking under pressure at the seam on the tank. Replaced it and no more issues."

"Our E82 consumes a little coolant as well. I top it off every 3-4 months, never amounts to much."

https://www.1addicts.com/forums/show....php?t=1388511

[swunder]

Dealer called me like an hour I dropped it off, leaking coolant tank. Didn't even think the car had time to cool down yet. Mystery solved at least!