Engine noise. Water pump?

[CrimsonEclipse]

2011 Yaris USA
When I first start up, there's a noise that sounds like an old school hydraulic pump power steering pump.
Since the P/S is electric....

The sound occurs stationary and in motion and changes tone with the engine RPM. It also goes away after the engine warms up. It's also a lot more noticeable in cold weather. The sound does not change if the A/C is on or off.

I'm guessing that it's either the water pump or the alternator.

I'm not losing any coolant.

Should I just leave things alone?

[sh0rtlife]

how well does the AC work....im wondering if the AC unit is on its way out, a cheep check would be to change the belt to a non AC belt, if the noise goes away then its the AC unit..if it doesnt, then remove the belt entirely and start the engine you only need it to run for 30 seconds or so..if you have no noise then youve now narrowed it down to the alt or the water pump....if it narrows down to those to then try hand spinning both of the, and you should be able to verify

having a NON AC belt in with the spare tire can save you HUGE if something should happen to the AC compressor or belt..the non AC belt can be swaped on the side of the road with little more than 2 wrenches and 10 min(12 and 14mm i belive).....ive been carrying a non AC belt in every ac car ever since i dropped a belt on a minivan out in the sticks...its saved me a tow on multiple rigs over the decades

[CrimsonEclipse]

how well does the AC work....im wondering if the AC unit is on its way out, a cheep check would be to change the belt to a non AC belt, if the noise goes away then its the AC unit..if it doesnt, then remove the belt entirely and start the engine you only need it to run for 30 seconds or so..if you have no noise then youve now narrowed it down to the alt or the water pump....if it narrows down to those to then try hand spinning both of the, and you should be able to verify

having a NON AC belt in with the spare tire can save you HUGE if something should happen to the AC compressor or belt..the non AC belt can be swaped on the side of the road with little more than 2 wrenches and 10 min(12 and 14mm i belive).....ive been carrying a non AC belt in every ac car ever since i dropped a belt on a minivan out in the sticks...its saved me a tow on multiple rigs over the decades

A/C works fine. Noise is the same with A/C on or off.

I actually have an extra non A/C belt for the event of an A/C compressor lockup, but right now, I'm far too lazy to swap the belts out since it's a million degrees out.

(but you DO have a good point)

[sh0rtlife]

the AC will make the same noise weather its on or off, as the clutch is "internal"..the only way to rule it out is to remove the belt from it

[esse10]

2011 Yaris USA
When I first start up, there's a noise that sounds like an old school hydraulic pump power steering pump.
Since the P/S is electric....

The sound occurs stationary and in motion and changes tone with the engine RPM. It also goes away after the engine warms up. It's also a lot more noticeable in cold weather. The sound does not change if the A/C is on or off.

I'm guessing that it's either the water pump or the alternator.

I'm not losing any coolant.

Should I just leave things alone?

I had a very similar noise 2 yrs ago and it wind up being the alternator bearing. especially during cold weather. they're fairly easy to replace you might consider buying a throw-down unit , put it in there . you'll have a spare for when it really goes completely out.