help! again!

[watty]

thanks for the feedback last time. been really busy so finally got time to get to my lockup to tryn fix overheating on my euro 86 528i. i drained the coolant, changed thermostat then wnt to refill. it sys in my manual it should take 15 litres but would only take 9! did this twice. started it up and after idling for 10/15 mins the coolant came boiling out the exp tank. top half of rad was hot with top hose and bottom half cold. temp gauge normal. there no water in the oil. i need to sort this as i don t want to do anymore to the car till i sort this out. dont want to really take it to a garage as was hoping to see a good e28 after my own hard work, even if im learning the hard way! hope someone can help as this is holding me back. cheers, watty.

[Sindre Osthagen]

Hi watty!

I did belive the engine cooling system took 12 liters of coolant fluid, but anyways; The reason your system just takes 9 liters could be because your engine still holds some of the old coolant.
Further on, your cooling system might have air locks after the flushing keeping the coolant from flowing through the whole system. Try to park the car uphill with the radiator cap off and the engine idling for a short while and see if there is any air escaping.

Good luck!
-Sindre-

[Sindre Osthagen]

Oh.. I forgot about the air draining valve in the thermostat housing on these engines. Have you let the air out this way by opening the screw slightly while engine is running and hot. Bubbles will build as long as there is air escaping.