Guys, I need your help!!!!
I just paid the dealer $1500 to replace the alternator, and within 2 days of having the car back, I find out my water pump main bearing has failed!! Dealer says this is unrelated and wants $1370 to replace!!!
What are the odds??? Could they have tightened the belts too much causing this failure?

Car is a 2004 with 110,000 miles


Any thoughts???? Please help guys - thank you

You need to find an Indie mechanic asap. You're getting ripped off back and forth. $1500 to replace an Alternator is highway robbery! :wow:

Any help guys?

Can improper belt tension cause water pump bearing failure?

Not a mechanic but;
Is not the belt tension determined by a tensioner pulley?
Wouldn't 110k more likely be the cause?
I paid 1300 bucks for a new alternator at the dealer, including 1 door ding removal.

Good luck.

I would still assume that you could screw up then tension though. The mechanic managed to leave the radiator completely loose as well, which I had to tighten down.

I know the mileage is high, but really, failure within hours of them messing with the belt system after the alternator repair?

I'm going to try and get the dealer to pay for the water pump, I'll let everyone know how it goes

no, the belt tensioner is what sets the belt tension. it is a mechanial design, and when turned to release the belt can not damage the water pump.

I understand that however I am sure you could still over tighten everything, regardless of the tensioner

I suggest you don't waste your time...it won't end well. It's perfectly normal for such a thing to happen, imo. I've definitely experienced it and learned that hard way that often times it's better to address a problem immediately as delaying will cause consequential damage to other components. There are other variables more likely to have caused the water pump failure than dealer negligence.

You've essentially received the same definitive answer that the dealer will give you...as a BMW certified tech (killcrap) just answered your question to improper belt tension causing water pump bearing failure.

My 2 tuppence...

Just FYI - dealer is paying for all labor for a new water pump, and they are throwing in a free thermostat as well. I will end up paying $500 instead of $1500.

I replaced a failed water pump on my 2002 4.4i a week ago. I used OE BMW parts ordered through ECS Tuning. My vehicle had 114K miles on it before total failure of the bearing. I mean, it DESTROYED the bearing. It took out the drive belt too. I suspect previous owners used non-BMW rated coolant like Peak. The used coolant did not have the right color and also smelled strange. Probably was never flushed or serviced.

The impeller is not the problem, regardless of material. The problem is either the belt tension and/or the coolant. The bearing/seals need proper lubrication which the BMW coolant can provide. Old or non-BMW coolant can cause problems leading to water pump failure.