Low coolant, no leaks or warning light.

[alphaod]

Did a cursory checks of fluids last night and noticed that in the coolant tank the level was so low I couldn't even see the coolant on the bottom. There are no leaks that I can tell and the car certainly didn't give me any warnings. I also checked the tiny one next to the motor—same low level. I'm wondering perhaps there is another expansion tank somewhere and when the engine is cold it's pumped somewhere else.

Any ideas?


(Otherwise I already drove it to the dealer to have topped it up this morning—so they have a record of doing this)

[xiaoata]

Originally Posted by alphaod

Did a cursory checks of fluids last night and noticed that in the coolant tank the level was so low I couldn't even see the coolant on the bottom. There are no leaks that I can tell and the car certainly didn't give me any warnings. I also checked the tiny one next to the motor—same low level. I'm wondering perhaps there is another expansion tank somewhere and when the engine is cold it's pumped somewhere else.

Any ideas?


(Otherwise I already drove it to the dealer to have topped it up this morning—so they have a record of doing this)

I have similar issue but not as bad, I can still see the coolant below the MIN line. I took it to the dealer and they just top it off, couple weeks later it drop down again. Where is the other tiny location to check next to the motor? The coolant system suppose it be sealed, the fluid has to go somewhere.

[ajob]

If there is a crack in the cylinder head, then coolant, when hot and under pressure, may flow into the oil pan - check the oil level, if it raises unexplicably, that's it.

Happened to me once - to find out: added a fluorescent tracer in water that showed a hairline crack in the head under UV light.

[ajob]

If there is a crack in the cylinder head, then coolant, when hot and under pressure, may flow into the oil pan - check the oil level, if it raises unexplicably, that's it.

Happened to me once - to find out: added a fluorescent tracer in water that showed a hairline crack in the head under UV light.

[alphaod]

I get my oil tested when I change it and there is no presence of water in it, so I don't think the coolant is leaking into my oil.

Anyways the level has been steady since it was last topped off and is still at the max line.

[c3uo]

I have two BMWs and have been fighting the same issue for the last five years.

My 2011 X3 35i with N55 has dropped ~1 cup of coolant per year. I replaced the coolant expansion tank last year thinking that fixed it. It did - for a while. Now it appears to again drop slightly every year. When it was under warranty I was told normal (BS). I paid for an oil analysis before the warranty expired and it did not show glycol in oil.

My 2015 X5 35d has COMPLETELY drained the expansion tank - twice over two years. The dealer did a lot of troubleshooting and pressure testing and claims normal. BS. It loses ~2 l per year. I asked for an oil analysis and fluorescent dye, but dealer refuses under warranty. I might just pay myself before warranty expires. I still think it is the EGR cooler.

I jokingly told them BMW must stand for bring me water. I love my BMWs, but these coolant issues are highly frustrating and part of the BMW quirks of ownership.