Water pump catastrophic failure

[Harley Monster]

I am kicking myself for not listening to what this car has been trying to tell me for the last several months. We have had a slight chirping noise coming from the fan belt area, not severe, but not normal either. I figured an idler pulley or tensioner pulley bearing was beginning to fail. It is now obvious that it was more than that.

Posted below are some photos of the result of a catastrophic failure of the water pump on our 2001 BMW X5 at 98,000 miles. This pump was changed out at 58,000 miles and is not the original (see explanation below). It is apparent to me that the bearing of the water pump failed taking out the seal and allowing the pump shaft to oscillate and collide in the water pump cavity destroying the impeller. As the shaft oscillated the fan blade took out the shroud and belt along with the blade.

I believe I have most of the parts ordered and the majority of them should arrive today from Pelican Parts. I am replacing nearly everything in the cooling system: New improved Stewart water pump with 20% more flow, 20% more bearing surface, SS impeller and improved seal; radiator hoses; belts; belt tensioners and pulleys; idler and water pump pulleys; fan blade; fan shroud; thermostat and housing and new expansion tank cap. Pelican Parts by the way has provided me with excellent service...they even responded to a tech question email I sent them in only 6 minutes!

I have decided to also do the heater hoses while I am in there, but have not order the parts yet.

I don’t think the water pump cavity is damaged enough to affect the performance of the new water pump as the machined circumference where the impeller rides is not damaged. The only damage is at the rear of the cavity.. I pulled all those pieces shown in the photo of the impeller out of the water pump cavity and I am hoping that any pieces that went through the system will not come back and haunt me later.

I plan on back flushing the radiator with a hose to remove any small pieces that may have made it into the radiator.

I am considering attempting to backflush the engine, but I have not figured out the best way to do this. I am open to suggestions from the pro mechanics on this site or those who know this engine better than I do.

I don’t know for sure, but I think the problem began 3 years ago when I took the X5 in to have the air conditioning recharged at a independent AC shop where I have been happy with their work. The owner called me and told me that my fan clutch was not working properly and I told him to go ahead and replace it. He later called and said they could not get the old fan clutch off the pump and needed to replace the pump too. I told him to go ahead. My guess is that they did not know about the left hand threads as the fan came off very easy for me using a pry bar between the pulley bolt heads and a 10" Crescent wrench.

I question the quality of the replacment pump they used, the pulley flange does say ”Meyle - Germany” on it but it could have been a cheap rebuild of a German pump, I don’t know, but that is my suspicion.

I am hoping that the engine did not overheat too much and take out the head gasket or warp the head which seems to be a common problem with BMW’s that overheat…we will see.


My recommendation...DO YOUR OWN WORK WHEN YOU CAN!

Harley Monster