My Prius has just over 15k miles. Recently, I notice a very faint, high-pitch whine coming from the front engine area during the first 25 minutes of starting during the mornings. Morning temps have been in the low twenties lately. I don't notice the whine in the afternoons. comments?
is this a continous whine or just durning the start up phase. IE: coolant tansfer pump whine like some of us get when it's cold. Or is it the Motor/Generator whine?
Several possible sources. Coolant transfer pump [10-15 seconds at startup]; inverter coolant pump [continuous]; throttle control motor [continuous, PWM-style whine]. Those are the loudest noises the car makes when the ICE isn't running, assuming you've got the a/c fan off. The inverter tends to make a soft, 10khz whine when under heavy loads [while driving!], and sometimes you can hear that through the AM radio as well. . _H*
wow, that long. Hmm. If you could try to localize it under the hood, that would help. Bad bearings in the inverter coolant pump, perhaps? If you stick your hand down in the hole in between and slightly ahead of the inverter and the relay block, you hit it; black plastic thing 2 inches or so across with a hose on top and another to the side. . _H*
Ohhh. I completely ignored this thread early on because when I read the title, "Faint, High-Pitched Whine" I assumed that it had something to do with American automobile manufacturers. Then it occured to me that "faint" is out of place. All I can think of, Doug, would be to take the car to a dealer and leave it overnight. Get there early and with a technical witness, pop the hood and start the car. Hopefully the whining will occur. My concern is that if you drive the car there the whining will subside on the way. But yeah, I agree with Hobbit, 25 minutes of whining is a long time.
I can barely hear the inverter coolant pump on my 2004 Prius. The thermos coolant transfer pump makes a nasty noise when cold, especially in temps colder than -30 C. In summer I barely hear it.
Hobbit, thanks for the post. Your inverter description seems to be exactly what I would like to eliminate. I just hear this when driving around town and braking between 40 mph to 20 mph. This is much more noticable when listening to AM radio. Is there a reasonable way to mask this???
