Replacing expansion tank

[koister2001]

I've replaced my expansion tank at 53k miles and it started to leak again at 80k. I plan to replace it this weekend. Can I drain the coolant in the tank and simply replace it with a new one? Or should I drain the entire cooling system? Please advise.

[omodos]

Hi fella

Personally I wouldn’t, but if you have coolant/water mix handy it cannot do any harm put some fresh stuff in there, out of curiosity, did the coolant tank just burst both times or spring small leaks? and did you take regular looks in the coolant tank to see if it was between the max and min mark?or did you leave that to your mechanics when you took it in for servicing?

I am asking because I have 34k on the clock on my 3.0 diesel, and wondering if I am driving on borrowed time? Well frustrating to own a $$$$$$ car and not know if you will lose all your coolant in a flash and bugger up your engine

On the same note are there any BMW technicians on this site who can verify if indeed this coolant reservoir issue is ‘standard’ on all e53s 1999-2008?including the 3.0l and 3.0d?

[koister2001]

It appears that the bottom portion of the expansion tank is bonded to the lid with glue. In comparison, the washer fluid tank is a one-piece injection molded plastic. Not the best design, but may be a price-driven design that works for some time. With the pressure and temperature inside, the expansion tank must be prone to cracking and delaminating.

[omodos]

Thanks thought as much, all about saving money, shame really on such a well built car, could cost drivers an engine if they dont catch on to the loss coolant quick enough,,,,,