I have a 05 G35 coupe. I was just told my water pump needs to be replaced (evidence of coolant leaking out). I got a quote from an independent garage to change out the water pump and the chains / tensioners to prevent any future issues for $2200. Local Infiniti dealer quoted to change out the water pump for $780. How likely is it that the tensioners become stretched over time and will need replacement anyways? I'm trying to decide which way to go. Any suggestions are appreciated.

 

The tensioner doesn't stretch, it's a hydraulic piston that uses oil pressure to maintain pressure against the chain. I would replace it since the part is relatively inexpensive and they will be taking it off to do the water pump anyways. The tensioner is good for roughly 100k, +/- 20k miles or so.

 

Replace your slack guide and tension guide while you're in there.

 

Yeah and depending on how many miles is on the engine you might think about a complete chain replacement (includes cam sprockets). It's a fairly expensive part ~$500 for the chain and sprockets. If you are close to 150k I would do the whole thing, if you only have 100k or less I'd just keep the stock chains, they're incredibly durable and long lasting.

Chain is rated to last "the life of the motor" but if it's got 150k on it chances are it's very worn.

 

Thanks for all the advice. I've got 153k miles so I think I'll change it all out.