[iknowitsfast]

Hi guys, I had my radiator replaced a week ago and yesterday morning I go out to my car and when I start it I got a 'low coolant' light. However I drove about 5 miles to a store. When I came out of the store and started my car, there was no low coolant warning.

This morning on my way to work, i start the car, theres the pesky low coolant light. When i drive a bit, stop for coffee, come out to my car, the coolant light doesnt come on.

Anyone know why this might be happening? I plan to stop at a dealership and purchase some coolant on my way home from work tonight.

[bhmax16]

Did you even check your coolant level? 99% chance the shop just didn't fill your resevoir all the way

[iknowitsfast]

i went and checked it, it was bone dry. I made it to the dealership and purchased some BMW brand coolant. I filled it up and the light is gone. I hope it stays gone and there isnt a leak somewhere. Good news though the SA at BMW of Schereville ran my cars history and it appears the HPFP, wastegates and the turbo were all replaced before I purchased the car. Now to see about the water pump....

[deg335]

Your engine should be cold, when you check coolant level. The best time is in the morning, before you start the engine. You can use any blue or green coolant liquid, not only BMW original.

[Efthreeoh]

Just to be clear, the tank in the engine compartment is a coolant reservoir and not an "overflow" tank as some cars have. Coolant is stored there; not just when the cooling system heats up. It has a Styrofoam float sensor attached to the stick that comes out of the fill opening. What is happening is your coolant level is just at the point (when cold) where it is triggering the float sensor, but as the cooling system heats up (and the coolant expands in volume due to temperature) the float sensor goes un-switched (the light goes off). You did the correct thing by using BMW coolant (it's the best practice). The question is did you use pure un-diluted coolant (not a terrible thing for the small amount you added) or did you buy the pre-packaged pre-mixed BMW coolant that some dealers sell?

Secondly, if you had the radiator replaced, did they replace the coolant reservoir cap too? As the cap ages, it looses some of its pressure holding capability (there is a pressure relief valve in it that wears out) and allows coolant to escape the system through vaporization. I suggest getting a new cap, they are about $20 at the dealer and $11 on-line). Other than that I can suggest is the shop did not properly bleed the cooling system when they installed the new radiator.

[iknowitsfast]

Thank you guys for the advice. I'm learning so much about this car. I just purchased the $23 bottle of BMW coolant in the gray bottle. When I poured it in, it was blue in color. The SA at the dealership said I did not need to add water so I just woke up in the morning, went out and poured it in until that little tip/needle device was floating a little above the top. Its been two days and plenty of driving and the light hasnt come back on. *knock on wood*