E70 35D mechanical water pump failure model
 

I had my X5 in for an oil change today, and the SA told me that the mechanical pump on the 35D normally fails in the range of 110k KM - 130k KM (currently have 119k KM). I know the electrical pump normally fails around 70k -80 k miles, but has anyone had the mechanical pump fail on their 35D?

If yes, at approximately what mileage? I'd rather change the pump and thermostat than have a failure on the way to our cottage (summer home) 1.5 hours away in rural Ontario. Of course I'll do the work myself and take some pictures :)

Not in my 35D, but it did fail at about 100k miles in my older X3. It's generally regarded as a wear and tear item.

First I do not know any statistics, especially about the x5.
But I think mechanical water pump failures are rare in cars in general.

Now what happens often and would be smart to replace is the thermostat.
When a thermostat fails and it sticks closed the engine overheats and.when bmw overheat.they can blow head gaskets or.crack heads.

Fyi my x5 service records show the prior owner had a thermostat failure at about 75000 miles and it overheated and blew a hose.

If your x5 is about the same miles it would be good to replace it. Also reminds me the x5 doesn't have a temp gauge. I need to get my bmwhat iphone reader hooked up so I can have that info.

Your X3 probably had the M54/M56 engine that along with all BMW 24 valve 6 cylinder engines have a water pump prompt to failure in the 40-60k miles range. OTOH older 6 cyl and V8s have a pump that last much longer.
blue dragon, I am sure that your SA has a very limited knowledge to the diesels, and she just assumed it has the same type of pump as M54/M56 engines. Considering that the diesel rarely exceeds 3000 rpm, I would not consider changing my pump until it fails or at a time of a substantial overhaul of the engine. That said, it is your car, and my assumption may be as wrong as of the your SA.

VW TDI change water pump with 100K mile timing belt. Same access, small additional expense.

I can see them leaking (mine was replaced @ 50 kmiles or so), but failing as in falling apart? Not on our diesels.

I didn't know that, thanks.

Uhh, water pump failures are a pretty common failure item. I know in the Miata world (my secondary car) you need to get those water pumps replaced when you do the timing belt, so 75-100k miles. They will begin leaking somewhere around 100-110k quite often.

As for the X5 thermostats, every failure I've heard of is a failure in the open position, not closed. So while it causes its own set of problems, it's not nearly as catastrophic as if it was stuck shut.

The only way to know for sure is to remove the belt and check the water pump for play. Bearings typically fail first, which causes the seal to fail and then coolant leaks.

51000 miles/5 years on my 2008 E70 when the pump failed. From what I read, this is/was a common problem in the X5.