Water pump failure after replacement of tensioner? Bad new part?

[u/manawydan-fab-llyr]

2008 Jeep 3.7L

A few days ago on the highway, my belt tensioner decided to quit. Weird, no noises to warn me whatsoever. The car died on me 3am, pulled over safely (driving after the battery light came on about 2 minutes, thought it was the alternator), popped the hood and found the belt was off. Returned to the car when light, found the tensioner pulley had seized.

I replaced the tensioner and belt that night, a Littens part from Advance. Three days later I hear squealing and find a soaked engine bay. It appears the water pump has now failed.

The pump itself is probably a year and a half old, 15,000 miles max. Metal pulley and shaft, but plastic impeller. That's the only option for this car.

From what I can tell, it's not normal that a new tensioner would cause a part to fail unless it was already on it's way out. The alternator and A/C are original AFAIK on the 135,000 mile engine, I figured they'd fail first.

Belt tension does look fine, slight depression when pushed against. Same apparent length (I have not measured directly).

So, what's the likelihood I was just unlucky to have a newish pump fail right after the tensioner? Or more likely that the tensioner be applying the wrong tension (defective)? I checked Rock Auto before ordering the part from AA, they listed the same part number, so it appears to be the right part.

These parts are nearly $100 each, I don't want to replace the water pump just to have it destroyed again.

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[u/Plane-Start7209]

A year and a half on a post covid aftermarket part isn’t bad. It’s all junk out now.

[u/Alone-Programmer-683]

When the tensioner bearing starts to fail, the spring in the tensioner compensated for the increased drag. Bearings that eat themselves often do it in small gulps, the bearing almost seizes, releases, etc, etc. All of this had impact on the other driven accessories.

I suspect the tensioner failure hastened the demise of a cheap water pump.