Low coolant light on a few times...

[Washburn]

It comes on when it's cold outside or when temp drops at night, etc. If I start the car for the 1st time of the day, it's on, and then if I turn it off and turn it on again, the light doesn't come on...
How much of a concern is this?
Car drives like normal and temp gauge remains normal. No coolant drops visible anywhere.

Is there a certain procedure to check correct coolant level? I read somewhere about turning the car to ON and setting climate control to 91F or something like that before checking...? can't find it anymore on the www

Also, do I need BMW coolant to top off? can I absolutely not use generic coolant just to top off?

[danewilson77]

You could use anything to top it up....abviously BMW blue is preferred.

The "91F...." statement is what you do when bleeding the coolant system.

I would do a proper "top up" and bleed of the system.

Do not overfill.

[Washburn]

Thanks, Dane.
OK so i don't need to do that part just to top off..

What do you mean by a "proper top up"?

I guess I just put some coolant in until the stick is level with the top of the neck? (to clarify: when coolant is LOW, the stick is also LOW right? and comes UP when you add coolant? not the other way around?)

[danewilson77]

Thanks, Dane.
OK so i don't need to do that part just to top off..

What do you mean by a "proper top up"?

I guess I just put some coolant in until the stick is level with the top of the neck? (to clarify: when coolant is LOW, the stick is also LOW right? and comes UP when you add coolant? not the other way around?)

Yes..you are correct. Need room in the tank for expansion. You may be pushing a bubble around....who knows.

[Washburn]

stick (top of it) was about 3 inches below the neck level.
...added about 3 cups of Peak Long Life (which is silicate and phosphate free, just like OEM stuff), and now the stick's top is juuuust above the filler neck level.
Will check if light goes back on or not when I start next time and in the next few days...

[danewilson77]

Good plan Washy.

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[LivesNearCostco]

Washburn: I have a theory about this, that when your coolant is a bit low and you turn on the heater, it opens a valve to route more coolant to the heater core and that triggers the low coolant light. The theory could be pure garbage though, since that would imply there are some air pockets in the heater core (or its hoses) when you're not running the heater, and we know that properly bleeding the cooling system is supposed to eliminate all bubbles except the one at the top of the expansion tank, right?

But you said it came on when the weather was cold. I'm curious if that was because cold coolant shrinks or because you were running the heater. If you always (or never) run the heater and it only came on when the car was cold, maybe it's just thermal expansion with a warm engine raises the level enough that it doesn't trip the sensor.

[danewilson77]

Washburn: I have a theory about this, that when your coolant is a bit low and you turn on the heater, it opens a valve to route more coolant to the heater core and that triggers the low coolant light. The theory could be pure garbage though, since that would imply there are some air pockets in the heater core (or its hoses) when you're not running the heater, and we know that properly bleeding the cooling system is supposed to eliminate all bubbles except the one at the top of the expansion tank, right?

But you said it came on when the weather was cold. I'm curious if that was because cold coolant shrinks or because you were running the heater. If you always (or never) run the heater and it only came on when the car was cold, maybe it's just thermal expansion with a warm engine raises the level enough that it doesn't trip the sensor.

I actually support this theory. It happens to me every day....and I'm not losing a drop of coolant.

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[Washburn]

Thanks guys.

my light came on withOUT running the heater.it lit up just when I started the car, and the climate control was off every time.
(I always turn it off before I turn the car each time).

so in my case, the light came on independent of the heater.

And of course the level (according to the stick thingy) really WAS low when I checked it today, and I added some...
However, i did note that the light only came on when it was cold outside...never when it was 55- 60F or above...

it's very possible that this car has its original fill of coolant from the factory...3 cups might have just 'vanished' (evaporated?) over 6 years and with the cold setting in and combined with the thermal shrinking, must have shrunk the coolant enough to trigger the light...i didn't see any coolant anywhere in the engine when I checked today...

[danewilson77]

Sure...especially if you have positively identified NO leak.

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