frigid this AM in chicago
never had this whine before
fluid level is correct
color is nice and red... not sure how old it is?
whine lasted about 5 mins until engine was warmed up a bit then noise was gone.
im guessing fluid is a little thick at that temp and so the pump had some cavitation?

should I drain and fill reservoir or completely flush the system?

 

Have this same problem, but not nearly as cold here in SoCal. Any help would be greatly appreciated.

 

Has it exhibited this in the past? I've heard some pumps whine a bit on really cold days and 0F is chilly. After a few moments the noise goes away as the fluid warms-circulates. A So. Cal car that has this in 50F would be due to a failing pump and or from reduced flow in the system.

 

Nothing works good in the cold. And the fluid turns into honey the colder it gets so expect noises that are not normal.

 

never heard it before but I also haven't started the car when it has been this cold either.

 

Update I just checked the level , it is 3F outside and it is right on the bottom end of the cold section on dipstick. I added a tablespoon of ATF and it quieted down. Hopefully not a leak(I don't see any) maybe just cold fluid contracted enough and a tiny bit of air got in?

 

Zero Fahrenheit is common temperature in Chicago...with windchill factors in negatives...

While engine oil reaches operating temperature in short order, I am not sure the P.S. fluid.ever reaches optimum operating temperature...and pushing thick 0 F Mercon III ATF is hard on the P.S. pump.

My 1999 LS400 P.S. pump was replaced with new Lexus part due to noise and beginning leakage.

.Does anyone know if Mercon III ATF is considered "synthetic" or if not, what synthetic brand product would apply....looking to replicate good low temperature results using synthetic engine oil.

I use 0W-30 Mobil Synthetic engine oil and cold start is effortless at 0 F.

 

Mobil 1 ATF is a full synthetic. Mercon III is petroleum based from what I've read of the formulations.

 

23F here in MD. warmest its been all weekend

 

My current 2008 Sequoia, and my 04 GX470 i used to own do/did same thing for a few seconds when being started on the days where it's below 0. I wouldn't get too worried about it.