BMW E36 320i Coolant level low when cold

[Bela27]

Hello, i'm from Croatia(Europe) and i'm new to this forum.

I have a problem with my coolant on E36 320i 1996 manual with 243 000km. I changed my water cooler and refill it with coolant. When engine is warm the coolant level is between cold and warm. I'm driving car 15km, turn it off and in the morning the level on coolant is below minimum(this happens 3-4 days) and i refill it and again after 15km and in the morning the coolant level is below minimum. The heat is working, the car is normally accelerating, my thermostat is not working because when driving it can't go at center(12 o'clock) it is at first white line(1/4), and if i drive in hills with around 4k rpm then the thermostat slowly grows but not to 1/2 and after again is cooling...
Can someone help me?

[ultimatetester]

You have a coolant leak, where else do you think the coolant is going? Probably your non-working thermostat caused some issues to your engine which now results in coolant leaking into the oil. Do some tests, look how your oil looks. Never had white smoke coming out of exhaust? If the oil looks fine and there’s no smoke then it must be another form of leak, look everywhere to see if you can find some coolant outside of the reservoir...

[Bela27]

It's about -5°C outside in the morning. When i turn on car, there is some white smoke, but when car warm up the smoke is gone(condensation?). So it's possible that coolant is leaking into engine oil or somewhere else? I will check that...

Edit1: i checked and coolant is not leaking in oil and oil is not leaking in coolant... any idea?

Edit2: yeasterday i checked the coolant level and it was at minimum at the same place like before i refill it, and i didn't refill it yeasterday and after some drive when the engine gets cold the coolant level is again at the minimum, so conclusion: it's at minimum, if i refill it and drive it will go at minimum when engine is cold, if i don't refill it will go again at minimum when the engine is cold, any suggestions?

[jc43089]

Are you filling past the "cold" line when the car is cold? If you overfill it some will leak out when the engine heats up. e36 expansion tanks only have one mark and it means full when engine is cold. The tank should not be filled to the top. I don't mean to insult you just making sure you understand the marking on the tank.

[Bela27]

I filled it below "cold". I changed thermostat, water pump, radiator, and when i'm trying to bleed it, i can't get the heat in cabine. And after i turn the car off, after some time coolant disapears.

Edit: i have heat, but after 1 week i lose around 0.1L coolant, where can be problem now?

[sharadn]

I had a similar problem and after chasing it for some time found that I when I had replaced one of the cooling lines under the intake manifold I did not align the hose properly on the fitting and it was slightly cocked. There was no sign of a leak ever on my garage floor but I guess when it heated up and was under some pressure it was leaking out. I checked for combustion gases in the coolant and there was none. Then I borrowed a cooling system leak tester and it immediately allowed me to identify the leak. If your level is going down the coolant is going somewhere.

[Bela27]

It was the water pump and i changed it, i refilled radiator twice in 2 weeks(together 0.15L) and now is the coolant level normal and i don't lose it.