Coolant Loss Due to Leak from Expansion Tank on BMW X3

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: 85,808 (64,000–120,000)
5 model years affected: 2004, 2005, 2006, 2007, more2008
29 people reported this problem
12 people shared problem details
2005 BMW X370,000
Took to the dealer. They replaced the water pump under warranty (thanks for the freebie). Not until I aquired a high pressure oil leak that I noticed oil and antifreeze mixed on the garage floor. I bought an expansion new expansion tank from BMW for $116.00 ($59.00 part on the internet) and fixed the thing myself in a couplr hours.
2004 BMW X386,000
Expansion tank blew out just as I parked the car. Loud bang, then coolant just ran out all over the place. Crack on side of expansion tank must be 5-6" long.
2004 BMW X3102,713
My coolant light has just come on and when out after three days and diagnostic that couldn't detect anything. Now my service engine soon light is on.
2008 BMW X364,700
Coolant low intermittently goes on and off. Never stays on. Mechanic (not the dealer) found a hairline crack & says it has a small leak, not enough to reach the ground. Wants to charge me $700 to replace the tank. Haven't fixed it yet - I am researching optios.
2005 BMW X386,000
I had the extension tank replaced about 2 years ago, and the coolant is leaking again.
Expansion tank cracked
expansion tank is leaking
2005 BMW X370,000
Coolant light comes on and off when car up to heat funny smell,when useing heater blower.tank had a very small crack on edge near where power steering pipes run past tank. This was a very hard leak to find as it only opens up when car is warm and blower on soon as you turn car off it closed up and was only about 2mm break which is very hard to see when no pressure. Changed tank and thermo at bottom as it breaks when removing easy d.i.y repair cost £80 on parts car works fine now
2006 BMW X393,000
Yep, leaking coolant, drips here and there, light came on, refilled, couple weeks later light came bk on, brought into shop, he cant find leak, but is assuming expansion tank.
2006 BMW X381,000
replace expansion tank and thermostat that connected to the tank.
2004 BMW X3120,000
losing antifreeze constantly
Coolant light was going on and off brought in to dealer, was told the expansion tank was cracked. After examing the tank, BMW said the cylinder head was cracked and the oil was thick and tarry. Car was serviced at an authorize mechanic at 55K. Customer service has requested BMW enginner to inspect engine. I got the impression they may suspect my maintaince under warranty.
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