So for some time, my '07 G35 sedan has been making a clicking noise. It's not regular, like valve tap. Instead, it clicks at random intervals; it sounds like click click click..click.....click click..click. Don't know if that makes sense, but it's just a tapping noise that's non regular.

So I took a mechanics stethoscope and I'm pretty sure I isolated the noise the the belt tensioner on the serpentine belt.

My question is, what should I expect to pay to replace this part? Also, I'm assuming I should replace the belts while I'm getting that done (they have 90k miles on them and haven't been changed). Is there anything else I should look at doing while I'm getting this done?

The reason I'm asking is because I'm thinking of trading the car in on a new model, and a high cost to do this would push me in that direction sooner rather than later.

If it is indeed the tensioner then it's probably a bearing issue. I don't know what the shop cost would be for installation but I've seen new tensioners online for around 90 bux. I've seen people claim it took them appx an hour to perform a belt change which requires loosening the tensioner so I would not expect more than 2 hours of shop time for the service. Make sure you replace the belt at the same time.