Funny Noise Coming Under Hood

The Prius makes alot of different noises, the most notable is the theromos bottle being filled but you notice this the most when the car as be turned off, not if your sitting at say a red light with the car in the ready mode. If everything is working all right I wouldn't worry about it.

 

Probably not a problem.

The "Energy" screen on the MFD shows energy movement (above some
threshold value) and not ICE, the engine, status. So unless you're
monitiring RPMs on a ScanGauge or something, it can at times be difficult
to determine whether the ICE is or is not running.

That said, can the occurance be isolated to:
cold vs. hot days
wet vs. dry days
ICE cold vs. warmed up
A/C on vs. off

Unlikely sources, but have you checked the radiator fan/serpentine belt?

You don't say where you're from. Maybe you have a saw whet (sp?) owl
caught under the hood/bonnet.

 

Hi John,

Are you familiar with the sound that the brake pressure accumulator pump makes? If not, depress the brake pedal repeatedly while the Prius is READY, to force the pump to run. That sound is normal.

If the sound that you reported above is different than the sound made by the brake pressure accumulator pump, then please let us know.

 

Did you ever resolve this? If so, what was the cause? I have the same exact sound you describe and will be taking it in for service next week.

 

I assume you mean that whirring sound. That would be the coolant pump that fills the thermos bottle (to quickly rewarm the engine when it does need to get started).

If you shut off the car after driving for a while and you hear that noise after shutting down, then it's the coolant pump.

Either that or you have Arsenio Hall hiding under your hood...

 

It's definitely not a whirring sound, it's a woo-woo-woo as in Curly from the Three Stooges kind of sound. Very different from the thermos sound, and this happens when the car is stopped but in Ready mode.

 

Are you hearing it, in place of the thermos sound? If so check your coolant levels... the woo woo, might be the pump dry heaving...

If adding coolant doesn't help, maybe it's time to have a certified tech look at it...

 

No, the thermos sounds fine. I'm almost certain it's related to climate control since it goes away when climate control is turned off.

The talk about hearing it when stopped is a red herring. It's a low sound and when the car is moving it's drowned out by road noise.

 

I have an '07 and I also hear that "whoosh" sound in addition to the ratcheting thermos coolant pump sound.

I've heard both of those sounds since the day I got my car back in '07 and it was never a problem for the past 2 years, so I'm sure they are normal.

I sure would like to know what's making that whoosh sound though!

 

Do you have your A/C or front defrosters on when you hear the noise?

 

Yes to the A/C, no to the front defroster.

 

Does it make the same noise if the A/C is off? (Front defroster off too.)

If not, then it might be the compressor.