Coolant Loss Due to Leak from Expansion Tank on BMW Z4

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.

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Average mileage: 72,938 (58,000–107,000)
3 model years affected: 2003, 2004, 2005
17 people reported this problem
9 people shared problem details
Found a hairline crack in the coolant expansion tank that was causing a slow leak. I replaced the tank and the problem was resolved.
2 people like thisFlag inappropiate
2005 BMW Z459,658
expansion tank developed a leak
1 person likes thisFlag inappropiate
2003 BMW Z463,400
Complete cooling system replacement inc. hoses and belts.
2003 BMW Z491,000
bought 1 week ago.after 4 days coolant light came on.tank bubbling and water leaking from it.taken to garage.engine runs nice.
2005 BMW Z462,250
Expansion tank started leaking, expansion tank, upper,lower hoses are being replaced. costs $700 at mechanic, $1500 at BMW service. I go with mechanic
2004 BMW Z467,500
Cost me 1000 and two weeks no zed
Cracked expansion tank
2004 BMW Z468,000
Coolant expansion tank pinhole leak
2004 BMW Z458,000
Top of the tank blew off.
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