5-Series (E12,E28, E34, E39, E60)Chat relating to the BMW 5-Series of all generations. Specific models include: BMW 518, BMW 520, BMW 520i, BMW 530i, BMW 528i, BMW 530i, BMW 518i, BMW 524d, BMW 525i, BMW 525e, BMW 528e, BMW 540i, BMW 535i, BMW 520d, BMW 525td, BMW 525d, BMW 530d, BMW 525i/xi, BMW 530i/xi. (BMW 5-Series Forum)
Hi I have a 00' 540i. Recently I noticed that coolant was leaking underneath the car. I opened the hood and noticed that the plastic screw near the expansion tank was spouting coolant (says entluftn near the screw). After the car cooled down I removed the big plastic screw and noticed that it went into a hose that hooked into the top of the expansion tank.
Do I need to replace this screw? or does coolant leaking from this screw indicate another problem, like too much pressure in the system.
that is your bleeder screw. when your filling the coolant system up aftre a change you have to take that out and fill it up until coolant comes out of the hole then you would put the screw back in and proceed to bleed the cooling system. i doubt that there is anything wrong other than a leaky bleeder screw. either on the screw or in the hole look for a little rubber o-ring. that needs to be there for the screw to seal. i'd prolly just go and replace the screw, it is and easy inexpencive fix. if a alot of coolant has drained out you of course will definatly want to top it up but you might want to re-bleed the cooling system, to make sure there are no air pockets anywhere in the system.
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