BMW 318ci - Losing coolant

[tigga]

Hi, i have a problem with a year 2000 318ci losing coolant, at first i suspected the pump and renewed the seal and applied gasket sealant therefore eliminating this.
I have read somewhere that this model may have a design fault whereby the coolant is lost via the header tank, does anybody have experience as to how this might be as there is no visible leakage but the level needs topping up every two days.
(there are no signs of head gasket failure)
Thanks in advance

[bigpup]

I cant see how it is going loose coolent into the header tank, as this part the the cooling system, unless it is venting out of the header tank cap, in which case you will be able to see this happening. Change your oil, and check it. If it appears to be thin, milky or sludge like, you may be loosing coolent into the oil, either throught a faulty oil cooler/head gasket/water rail etc..

[tigga]

Thanks for the answer, this problem has been going on for weeks now, we eliminated head gasket failure and eventually discovered the design fault in the header tank (for future reference) : It is made from too hard a plastic therefore it cracks at a seam when it gets hot, under pressure and expands slightly, (this pressure must only cause it too leak at high revs and any spillage dries by the time you stop) so of course, when its cool you dont see the crack !.

BMW completely deny any design fault but this has happened to a number of people we have spoken to so i guess the only thing we can do is buy another header tank and see how long this one lasts as there is no modified part available.

Once again, thanks for the suggestions.

[bigpup]

That makes sense, the only thing you can do, as you say, replace the header tank and try and sort it with bmw!!