Coolant Loss Due to Leak from Expansion Tank on BMW 330Ci

Problem Description and Possible Solution

An engine coolant leak may develop from the expansion tank resulting in engine overheating. When a cooling system component fails the entire cooling system should be inspected. It is not uncommon to find additional component have failed or are leaking.

Overheating can cause severe engine damage. If the engine begins to overheat it is recommended to stop at the first available location and have your vehicle towed to a repair shop.

Problem Data
RepairPal Verified
Average mileage: 90,418 (52,481–125,000)
6 model years affected: 2001, 2002, 2003, 2004, more2005, 2006
26 people reported this problem
Viewing 1 - 13 of 13 comments
coolant leaking on the ground when parked. Keep refilling it. How much will this repair be? I've had the car since April 2014 and already spent $2000 on it!
Expansion tank failed, when replaced it failed again leading to complete engine failure
had a leak from the expansion tank hose.
expansion tank cracked
Expansion tank overflow when it is hot or engine turn off
96000 miles same stupid problem...
leaking coolant
2002 330Ci Same deal. Developed small leak in expansion tank. Took me a while to find where it was leaking from. Removed coolant tank and it appears that when the original tank was made there was a very small crack in the plastic that just got worse over time. Had I not found it earlier it would have been a disaster. No lights came on to warn me. Just that familiar sweet smell of antifreeze every time I would get out of the car after driving. Bought a Meile replacement from eBay for pretty cheap. Did it (pretty easy replacement job) at 70K and still working good 5K later. I did not replace the cap as the rubber inside was still very good. I did drain flush and fill with new coolant mix, checking to make sure the coolant level remained towards the top as it comes out the top. Checked it a couple other times over the next month. Added a small amount of fluid each time. Have to get the air bubbles out of the system. Just goes to show: A well cared for car goes a long way.
rough idle and overheating
Replace expansion tank, disa valve and thermostat
my coolant tank failed
Surprise me when I saw the temperature instrument doing strangers movement , at the end
another light come on in my cluster showing that the is a cooling water problem, lucky that
I was close by to the BMW dealer , immediately I spoke with them , an they dertmine that
the extension was complete damaged (Repair cost was $400 USD)
tank leaked
constant drip