A new T-belt won't add any labor charge to the job - just the cost of the belt. You know how many miles are on yours / how many miles are remaining / the cost of a new belt belt / the labor cost when it DOES need to be replaced (if you don't do it now). Do the math.

I wonder how many miles before that water pump started leaking?
You might ask if the leak was at the pump shaft bearing or was it leaking around the gasket? Did the pump start leaking or did it leak at the gasket?

Maybe there there wasn't a complete removal of all the old waterpump gasket? I found that you need RTV and the gasket at the waterpump, especially if the mating surface gets messed up, which is easy to do.

Bill

Tbelts are relatively cheap, as are tensioners and rollers. If you change the Tbelt, you really need to change the tensioner.

The dealer will charge you a lot for the H2O pump swap, but well worth it as the screws are a pain in the back. Correct about the after market pumps, they just don't last!

You didn't say when the Tbelt was changed last or how many miles on it. The aftermarket belts are usually pretty good.
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My back feels better when I sit in a Volvo seat