2008 SLT 4x4 5.7L Hemi 124,000 miles

I am considering replacing my serpentine belt due to mileage but I'm wondering if a new belt may then cause problems with the water pump or idler pulley, etc failing soon after due to the new (tighter, unstretched) belt?

 

No. Just replace it.

 

The tensioner will only tension so tight, it will have same about of tension

 

Thanks, makes sense.

 

While you got the belt off, do this....

https://dodgeforum.com/forum/2nd-gen...g-pulleys.html

 

Water pump should be fine (unless it already has something wrong with it), check your idler pullies to make sure they're still good and your tensioner. It's cheap insurance to get a set but not a requirement to replace the belt. Had a tensioner actually go out on me on a 5.7 and didn't realize it til I was looking at some thing else; never made noise, overheated, alt charged correctly. No symptoms whatsoever.

 

My 1500 had one of those plastic idler pulleys deteriorate and ruin the belt. They were pretty inexpensive, I'd replace as part of the belt replacement if they are still original.