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Replace water pump as preventative maintenance?

My dealer recommends replacing the water pump and thermostat on my 2004 Prius. The car has 125K and doesn’t have any cooling problems. The owner manual doesn’t mention replacing the water pump or thermostat at any mileage. Should I do this? Or wait until I have a problem? Thanks in advance

If the dealer isn’t doing some other work (like timing belt on so-equipped cars) that will have the water pump exposed anyway, I’d wait till there was a problem. It can be an expensive job.

Look in your owner’s manual, it should say in the maintenance section.

Does the gasoline engine have a timing belt? If so, it’s probably due to be changed, which is important. With most engines the timing belt has to be removed to access the water pump, so it makes sense to replace it if that’s the case.

Thermostat? Maybe. Is the engine not warming up properly? It would make sense to replace if: A. it is malfunctioning or B. the cooling hose that it’s coupled to needs to be replaced anyway.

If you’re driving it every day I would change the thermostat every 4-5 years when the coolant is changed.
Your manual probably has a longer interval for the original coolant, like 7 years, then every 5 years.
Wouldn’t hurt to do the first change a little early.

Leave it be unless a timing belt if applicable or other work is going on that makes this work essentially free in labor.

Thanks for your reply. The owner’s manual does not specify ANY maintenance on either the water pump or the thermostat. The gasoline engine has a chain, not a timing belt. Sounds like the dealer was trying to get me to do unneeded work.

If it ain’t broke don’t fix it!

Your dealer has a lease payment due. He wants you to help make it.

The only reason we recommend having the water pump changed on some cars is because they have timing belts that also run the water pump, and the work and cost to replace the timing belt is high enough that it’s financially prudent to change the water pump while everything is apart. It adds little to the overall cost and should the water pump fail the whole thing would have to be opened up again anyway.

If, as was said, the water pump is not driven by a camshaft timing belt as is the case with some oriental car designs, then you can run it until it fails. Failed water pumps for me, as well as being seldom, have not been catastrophic. Instead, the water pumps leaked a little antifreeze solution from the shaft seal. This is detected by a coolant leak on your driveway or wherever you might park on a paved surface. Just add antifreeze and drive to a dealer.

A thermostat can last for the the life of the car and if it fails open, will not stop the engine. I have not had one fail closed which would cause overheating.

If you change the water pump and/or thermostat after 125k miles, it is likely that you will not need another for the life of that car.