Serpentine Belt Tensioner Lifespan

[uberwgn]

I am going to replace the serpentine belt on our 2002 E320 wagon this weekend. I suspect the belt is original from the factory. It carries GATES as mfr and has the MBz part number on it. It's looking tired.

I can see the replacement is very straightforward. I can move the tensioner very easily....it concerns me a bit and I am wondering how long the tensioner might last. This car has just under 60k miles.

I pulled out my torque wrench and I can start to move the tensioner with just 22ft*lbs of torque which seems low. I don't have any experience with tensioners on these cars and wondered if there is a test to determine if it should be replaced.


Thanks.