A high-pitched shrill whistling coming from under the motor hood


Asked by Jul 27, 2017 at 03:54 AM about the 1999 Toyota Vitz

Question type: Maintenance & Repair

I got a Toyota Vitz 1999. I am in search for a solution to the problem commonly found in all Toyota Vitz cars. I permanently hear, first it was only in winter but now in summer too, a high-pitched (nearly ultrasonic) whistling under the hood, roughly somewhere near the alternator. The whistling always appears when I accelerate the speed or decelerate it while driving, whereas no whistling sound occurs while driving smoothly. Some say it might be due to either the loosen (poorly tightened) alternator belt or the loosen timing chain. But this is not the case because I have them both certainly tensioned well to rule out this kind of high-pitched shrill whistling.  
Maybe the reason is, the throttle valve or idle valve has been clogged with dirt making it a whistler and I should demount both and clean them from carbon deposit and lubricate the bearings?
Any other ideas or anybody knows how to get rid of the whistle?  

4 Answers


idler pulley, or tensioner pulley bearings are bad.

1 people found this helpful.

auto or standard tranns ?


it's auto transmission. Concerning the idler puller and tensioner bearings worn out, maybe you are right. You think lubricating them will help, or it would be better to replace the pulleys with new ones?

1 people found this helpful.

if you can get a long bar or screw driver to place against the pulley area and your ear on the other end , like a stethescope , you should hear the noise , be careful you know everything will be turning , then you may locate the problem without replacing good parts , if it was a standard it may have been a throw out/pilot bearing

1 people found this helpful.

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