"Check Coolant Level" warning

[Suschords]

Hey All,

In my 2000 740il, today when turning off the car after a short drive I got a "ding" warning on the dashboard with the message "check coolant level." From there I drove about another 2 miles or so till I got home, keeping an eye on the coolant temp gauge which was fine.

I had my car in the shop about 2 months ago for an oil leak, and they did a pressure test of the cooling system and told me there were no leaks at that time.

Once I got home and allowed the engine to cool, I removed the cap for the expansion tank and looked inside: I could see all the way to the bottom. Only a little bit of coolant in there. Looks like I may have a leak after all.

I grab my 50/50 coolant jug that I keep in the trunk for emergencies and slowly started to pour to fill up the expansion tank, keeping an eye on the red level sensor - what's strange however was that the coolant filled all the way to the top of the tank, and the bobber never popped up!

I left it alone for a couple of minutes and allowed the coolant in the tank to drop a little bit (it didn't go down much) before reaching in and seeing if the red stick was stuck or something - I managed to get it moving enough so that the top of the stick now floats enough to sit flush with the top of the reservoir, but it still does not go any higher than that - I remember in the past it used to pop up past the top if it was filled too high. Even by me grabbing the stick and trying to pull it up, it still won't go higher than the top of the tank.

With the cap still off, I turned on the engine to check if coolant would start circulating - after a couple of minutes I didn't notice any activity - the coolant did not seem to be moving. At that point I got a little worried that I was in over my head so I put the cap back on and closed the hood.

I have to go to work in the morning and I have a long commute - i'm a little worried at this point. I hope its safe to drive for now, but I'm a little worried that I may have put too much in the expansion tank .... At this point I don't know if its an issue with the tank, or the level sensor, maybe all of the above and also there is a coolant leak as a kicker....

Does anyone have any recommendations for me? Thanks so much for your time!

[Timm]

If the float doesn't, er, float then it is internally failing and may be the source of the leak - the float with its magnetic disk goes around the sensor cavity, if the float is stuck then the cavity is falling apart - time for a new one!

[kahlilj]

Great vid Timm!