When it overheats you will know. Unfortunately, the water pump is a mechanical device and normal wear and tear takes its toll. I have changed out a couple of them on my 2000 528. There is no indication on how long one should last. One thing that will help is to add a water pump lubricant to the cooling system.

Ed

 

The coolant pump in my 2006 525xi just failed at 89,000 miles. Left me stranded on the highway on a very cold night waiting for a tow truck.
Repair cost at Dave Walter BMW in Akron, OH was $1,100 (Parts: $580 (rmfd pump, aluminum screws, coolant), Labor: $440, Misc/Tax: balance). Fault code stored in DME was for Electric Coolant Pump Speed Deviation.

 

2006 525XI 106K running original pump.

 

went around 101,000 miles and replacment cost about $950

 

To those of you that made it past 100k on the original pump, how often do you change your coolant?

 

I made it to 85k on the clock.... I have been told by a friend/BMW Tech of mine that they should last 75-100k miles... I think a lot of it has to do with the wear you put on it. Paid $160 to have it replaced but that was on the side by a BMW Tech... Its def a DIY'er though - I helped through the whole thing and have done them in other cars myself. Find a good shop or make friends with a tech outside of the shop!

And when it is failing you should get a warning on your idrive for heat and low coolant levels as they will often leak when failing.

 

I changed the coolant every 3 years, twice for my 2006 525xi. Also, I replaced the radiator (original leaked), thermostat and hoses at 80,000 miles. I should have done the water pump at the same time, knowing what I know now. DIY of the thermostat and coolant pump is a 5 star cursing/bloody knuckle job in my book. Not particularly difficult in theory, but the location of the thermostat and water pump is in a very tight place under the front passenger side of the N52 engine. I had to remove the coolant expansion tank for any kind of access to the top of the thermostat. Not much room to loosen/tighten hose clamps. Bavarian Autosport recommends replacing the coolant pump at 100,000 miles in their maintenance schedule, which I follow pretty closely.

Symptoms of the failed water pump in my case were:

1. Complete loss of cabin heat coming through the vents was the first thing I noticed
2. About 3 minutes later a yellow iDrive warning came on that stated the engine was running hot and that I should begin driving moderately to cool it
3. About 30 seconds after the first warning I got a red iDrive warning that the engine was overheated and that I should stop the car immediately

 

These fail a lot because they use plastic for the impellers instead of metal. Changing water pump is cheap and easy though. You can get a metal impellar water pump from ECStuning for like $55 (cheaper than our cup holders).

WHEN I CHANGED MY PUMP

 

Not cheap or easy for an '06 525xi N52, which uses an electric coolant pump (#11 51 7 586 925), not the belt-driven type you show in your post. There is no $55 aftermarket electric coolant pump, if you get a remanufactured one for $400-450, you are doing well. Also, the thermostat in the 525xi N52 is not the same as you show in your post. The book time to replace the coolant pump was 3.9 hrs for the BMW Tech. At $110/hr labor, thats over $400. I replaced the radiator, thermostat and hoses myself in about 7 hrs. By far, the hardest part was removing the old thermostat and installing the new one. There are two hoses with screw clamps on the back of the thermostat housing that are nearly impossible to access and work on. Removing the thermostat is a preliminary requirement for replacing the coolant pump.

Different cars, different parts, different ease of access, different repair costs.

 

Snap I always forget that 525s have N52 and M54... huge difference. My bad.

ECS has the thermo and waterpump decently priced- http://www.ecstuning.com/BMW-E60-525...gine/Cooling/2

There's like 10 videos on how to change the M54 pump and none on N52 (3 minute search). Time for someone to make one