05 Prius Bearing/Pulley Noise

There's a water pump pulley. If the water pump is over 100k miles, then it's probably time to replace it

 

I would replace everything, pump, pulley, belt

 

How long ago was it replaced?

 

Recall was on the electric pump

 

Yes 2 pumps. 1 for the regular motor, 1 for the electric motor.

 

Sometimes a length of heater hose held up to the ear can help narrow down a noise location. Or a mechanic's stethoscope if you want to get fancy.

 

Mechanic's stethoscopes are really inexpensive and work wonders. If you had one, you'd know your noise source in a jiffy.

It could very well be your idler pulley ... that was the only thing starting to get noisy on my old Gen 1 by 238,000.

-Chap

 

I would agree that the idler pulley bearing should be checked first. Check the tightness of the belt first because that can make noise also. Does it make the noise when the engine isn't running? That would point to the electrics, of which there are three; coolant storage tank pump, inverter coolant circuit, and a backup ICE electric pump to cycle the coolant in cold weather when the ICE is off and cabin heat is requested. Does it make noise while the engine is idling? If so, a careful spritz of water from a hose on the bearing might temporarily quiet it and indicate the source of the noise. Could be the mechanical water pump bearing, especially if you see dried pink antifreeze crust on the pump housing and a curious pink crust line drawn across engine compartment components and the hood soundproofing in line with the pulley radius.

 

If you're going to take the trouble to remove it, you should just replace it. All those parts combined are fairly cheap if you DIY

 

Open the hood and put your head down in there and listen. Sometimes helps to roll up long piece of paper into a tube and use it to listen.

In order to get the engine to run continuously go to Youtube and look up PRIUS INSPECTION MODE. Few button pushes and the engine will run continuously for testing and listening.

Have you ever run the engine so low on oil it threw an alarm on the dashboard?

 

A mechanic's stethoscope is, like, six dollars at walmart, and so much more definitive than rubber hoses, paper towel rolls, etc., it's like night and day.

Mine lives in the car at all times....

-Chap

 

Agreed but in this instance cardboard tube would probably suffice.

 

That's probably ok. You can't go wrong using Toyota SLLC.

If you haven't, be sure to look up the procedure for air bleeding the system ... pockets of air trapped in the cooling system won't be good for the engine long-term.

-Chap

 

Ditto all this. If you're not familiar with bleeding air from the Prius engine, definitely do this. It's pretty tricky and very important. Toyota mechanics even don't get it right sometimes. Two tricks you need to learn--run the CHRS pump manually and use the upper radiator bleed valve.