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Water pump breaks serpentine belt?

The serpentine belt in my son’s 1999 Chevy Lumina broke. The repair shop replaced the belt and the tensioner. $180 repair bill. The night he got the care from the shop, the belt broke again. This time, they said the water pump froze up, broke the serpentine belt and bent the pully on the tensioner. $275 to fix it this time. Does this sound right?

Well the question is; was the water pump at fault for the first break too? A good mechanic would make sure everything is rotating freely before putting the new belt.

I find it hard to believe the shop didn’t check the water pump - the serpentine belt drives the water pump, alternator, power steering pump, and A/C compressor. If the water pump is frozen, likely it would at least break/throw the serpentine belt.
The shop should have checked the water pump bearings for play, and made sure all of the other belt-driven accessories were rotating freely before they called it “fixed”. I’d hope they’re only charging you for the water pump repair, and replacing the belt and tensioner for free this go-round. They screwed up the first time.

It doesn’t, and here’s why: if the water pump froze, the event would result in a very loud squealing sound and smoke coming from the belt as the belt was propelled by the drive-gear over the stopped water-pump pulley. The belt would eventually break, but not right away if the belt was new. The car would rapidly overheat in the interim. Finally, it is unlikely that the shop went ahead and replaced both the belt AND the water pump (which would be required) for the second, slightly higher price.

But there is a caveat: it could be that your son’s car now has a brand new water pump as well as a new belt. Check it out. It might be that the shop replaced the water pump and the second belt replacement for the cost of the parts and partial labor. Look to see if the car has a new water pump as well as a new belt. If so, the second price is fair.
If not, the reason given for the failure of the first belt replacement is just bogus, and the second replacement of the belt should be free.
If you don’t have a new water pump, why were you charged more to replace the belt again? Shouldn’t the cost be the same? And if the shop thought the water pump could randomly freeze up, causing belt failure, why didn’t the shop replace the water pump? Isn’t it going to just freeze up again?

When a serpentine belt breaks it’s usually because the belt just wore out, or that the tensioner (which to me is the “weak link” of the various pulley-equipped items the belt drives)–that the tensioner went out of alignment, or that the spring in the tensioner, which keeps the belt taught, just rusted up and stopped putting tension on the belt.

When I replace belts, yes, if I think the tensioner is on its last legs, I will recommend new belt, plus new tensioner. But most mechanics, when they get the old belt off, they give all the pulleys a spin by hand and see that they spin true. (Spin with no wobble)

I think they knee-jerk replaced the the tensioner and belt, without checking the other pulleys, one of which was the water pump pulley. Of course, if they had done a good job to begin with, the initial cost to you would have been more than it was. The net grand total you should pay is what it would have cost to replace the belt, tensioner, and water pump right off the bat. (I’m temporarily assuming here the tensioner needed to be replaced.)

If you cry on their shoulder about the aggravation involved for you, maybe you could get’em to give you some amount of goodwill discount, too.


It should be the shop’s responsibiility to check everything related to the belt/tensioner.

While not definite, it’s possible to have a water pump freeze up intermittently and possibly due to heat. This could have been the cause of the first belt breakage. Once cooled the water pump would rotate again until the next seizure.

However, one can usually notice roughness or binding in the water pump shaft between episodes and the shop should cover all the bases rather than throwing a couple of parts on and running it out the door.
This is all assuming the water pump story is legitimate and that it’s not BS designed to cover up a screwup (say a loose tensioner bolt) on their part.

I have not replaced many water pumps on the Lumina but I have done many alternators so I am familar with the layout. It will do no good for me to say I never saw a water pump freeze up on the Lumina, but I will anyway.

My feeling is the belt broke initally (and even that is pretty hard to believe as these belts always made noise or some how got the owners attention before breaking). So we have two odd things, a serpentine belt breaking (as opposed to shredding) and a pump freezing up. I believe that the mechanic had trouble with the tensioner on the Lumina as it is pretty tight quarters to work in and if you don’t know what you are doing it willl give you trouble. I think the mechanic damaged the new belt and pulley at the first visit and the result was another belt breakage and the damage done by the mechanic at first to the pulley.

Were you shown a locked up water pump (after it was taken off the car) so you could see nothing was locking up the pump but the bearing or impeller?

I have no advice on how to get the shop to pay for this work, I merely offer a speculative explaination of events.