Coolant Loss Due to Leak from Expansion Tank on BMW X5

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: 101,370 (10,400–247,000)
Engines affected: 3.0L 6 Cylinder, 4.4L V8, 4.6L V8, 4.8L V8, V8
9 model years affected: 2000, 2001, 2002, 2003, more2004, 2005, 2006, 2007, 2008
72 people reported this problem
Viewing 1 - 20 of 28 comments
Expansion tank was cracked. I purchased a new one and installed myself (very easy) and solved the problem. If only all of the other fluid leaks on this car were this simple....
expansion tank cracked, towed to dealership for repair, replaced with new tank, cost me over $800 in total. crazy!!! my fetal $21K mistake. Just bought last month and this car already cost me so much trouble, don't buy used BMW, I may have to trade it in for a Japanese car.
Had truck running charging the battery, after about 20 mins I see water gushing from underneath. I turned it off popped the hood and noticed a crack in the resivour box... Is this a recall item???
I noticed it starts to overheat when i accelerate harder. If i drive it normally its absolutely fine. The temperature gauge rises and when i open then bonnet the leak is on the actual cap of the expansion tank. Could it be that i need a new cap or should i just buy a new expansion tank??
Vehicle lost all fluid instantly, luckily as I parked at my house. No overheating warning. It cost 625 to replace tank and do full coolant system test and the dealer.
Expansion tank split at the seam. Had tank replaced at Reliable Import Service in Raleigh NC.
I experienced a coolant leak when I had the error message on the dash for low coolant. It was the expansion tank that had cracked. All coolant parts were inspected and this was the only issue in the cooling system so far. It happened soon after I topped off the coolant in the expansion tank.
Radiator leaked. Replaced radiator. Hoses then leaked resulting in replacing all of the radiator hoses. Now the Coolant Expansion tank has a slight crack and is leaking. I replaced the expansion tank. Now the car is still over heating. Going to replace the thermostat and water pump which will hopefully stop my overheating and leaking problems. This car is nothing but a big black hole money pit!!! Stay away Dont by a BMW unless if you always want to be spending money on repairs!!!!
2003 BMW X5 4.4L , coolant tank failure at the seams of the tank, leaking coolant onto the alternator which lead to a failed charging system.
I find it completely ridiculous that people pay tens of thousands of dollars for new bmws and every single problem is a known bmw manufacturing flaw. My mechanic said he could have patched hole in my expansion tank crack if it were metal but once again bmw used inferior plastic part. I've also had the well known sunroof defect and the door handle can't open my front doors defect. Oh and the headrest defect and the gas cap defect. Cheap cheap manufacturing and parts for such a pricey car bought new. Ridiculous bmw you know there are thousands of us with same complaints.
Sides split on plastic overflow/fill tank. $800 to repair. Did water pump at same time--- Over $900 repair cost.