Hello everyone, I need some suggestions about a really confusing issue, and yes I have searched intensively.
I replace the coolant reservoir and cap, lower radiator hose, all the upper radiator hoses, thermostat and water pump, I see no visible leak but every 2 weeks or so I get a low coolant warning.
I add distilled water then the same happens two or three weeks later.
What's the deal with that?? besides this I have the dynamic drive warning comes on every time I turn the wheel,I'm about to trade the 2006 530i for a corolla! Lol!

 

Hey,
Did you ever get this solved? I'm having a similar issue. Changed my coolant tank Behr, new cap. Bled the coolant system I'm with a 550i. Ever since I get a coolant warni g once a month, and have to top up 1/4 cup.

I think mine is leaking through the cap and dripping down behind where there is a drain.
Checked my engine temp and radiator temps today and they were fine. Can't figure this out!

 

Going by the op's message if you’re only using water instead of the 50/50 bmw coolant you’re bound to evaporate the water and loose coolant therefore.

 

A quarter cup is not a lot! How many months has this been going on? What are you topping up with? Using water only will dilute the coolant and change its boiling point i.e it will boil off at a lower temperature. Still, if your cooling system is tight, you shouldn't be losing coolant no matter what its strength. Can you get a pressure test done? And, there is the infamous coolant pipe on the N62.

 

So I had a coolant pressure test today, passed no loss.

Ever since I replaced the coolant tank drips have been forming below the tank. On close inspection they are from the cap. Pressure test passed.

I hooked up my scanner engine temp is staying at 100c once at temp. Radiator stays between 60c and 80c and the fan will run as necessary.

I haven't been able to get the map thermostat to record any thing in my scanner though. Seems like I might just have a bubble stuck in the heater core or something? Or a faulty coolant level sensor (though that was replaced with the tank)

I'm at a loss to explain it. So is the mechanic.

 

I had a coolant leak in my car I've fill it up in the morning drive to work and it would be empty by the time I got there and two shops nobody could find where the antifreeze was going well there's a antifreeze line on the base of the firewall kind of towards the middle on the right hand side a little bit towards the driver side if you're looking at the front of the vehicle there's and it has a little bit in the middle of it and there's two lines that connect to that bib and the top one always seems to come loose so as you're driving it's just shooting it right out against the firewall but when you look at the engine the engine looks dry because you're not seeing it because it's coming right down the firewall and going right out the back so if you have an equivalent issue I'm not saying this is going to be yet but check the firewall line because I'm telling you 9 out of 10 times when they can't find the coolant link that's where it is and you fired the car rev the engine and you'll see it just spraying out of there

 

My son's E90 lost coolant slowly and without any visible trace. We searched and searched. Of course, there's water dripping under the car, where the a/c condensate drains. Tasted it - coolant. Leaking heater core.