2001 Prius. Within 15 seconds of starting the engine, I captured the screeching sound from the engine bay. Noise went away after about 20 seconds. New serpentine belt and new 12v battery installed. Pass dealer 27-point check. Transmission fluid, inverter fluid, high voltage battery were replaced about 18,000 miles ago. Current mileage 174,000. Noise is not from the serpentine belt. I attached a mp3 file of the sound. Delete the .zip suffix to play "2001 Prius Noise.MP3" Any ideas which component is making this noise? Thanks
I did not listen to your file. However if you are sure that the serpentine belt is not causing the noise, maybe the air conditioner compressor clutch is slipping? You can rule that out if you hear the noise when the AC is turned off. When the serpentine belt was replaced, was the engine coolant pump and the idler pulley checked to make sure that both are turning smoothly?
The water pump was replaced 25,000 miles ago when the serpentine belt was replaced. This time the mechanic replaced the serpentine belt 4500 miles ago. He said the idler has no problem. Now I believe the replacement of the serpentine belt is unnecessary. I cannot recreate the noise now with the AC on or off but this fits the current symptom (morning starting has noise, later on starting has no noise). Where is the AC Compressor located? Does this mean time to replace AC compressor? Thanks Patrick for the reply.
1. Was the correct Toyota part used when the serpentine belt was replaced? If an aftermarket part was used, perhaps that is the problem. 2. The Classic air conditioner compressor is spun by the serpentine belt. If you look at the engine, on the passenger side of the car, you will see the compressor mounted to the engine with its pulley spun by the belt. Press down on the belt with around 25 lb of force and see how much the belt deflects. It should not give more than around 1/4" or so. Also look at the belt to see if the surface that contacts the pulley is glossy or a matte finish. It should not be glossy as that would show the belt is slipping. 3. If the noise is caused by the AC compressor clutch then it would be time to replace the clutch. It is not necessary to replace the compressor if air conditioning performance is satisfactory.
The belt is Toyota parts. I have discovered how to re-create the noise. The Prius has to be off until the computers went to OFF-state. Turn the key to ON without starting the engine. One can hear the computers booting up with the corresponding mechanical sound. At around 15 seconds, there is two screeching noise coming out near the passenger-side firewall area then there is no more sound (seems like the computer finished the boot-up sequence). Attached is the .mp3 file. You need to delete the .zip suffix after downloading to play the file.
If the sound is from the firewall, maybe it is coming from the brake actuator assembly? Does the sound occur while the car is being driven, or only upon startup?
I first noticed the noise about half a year ago when I back the Prius out from the garage. But it is only intermittent. About a month ago, I caught the sound while driving on freeway, at a slight grade and changing lane. Afterwards, there maybe another time I heard the noise while driving. Today is the first time I have isolated the noise to the computer booting up. If I left the Prius sit for only half an hour then turn the iginition key to ON only, there is no boot-up sound. Seems like the Prius keeps the computer at ready for awhile. After letting the Prius sit for about 3 to 4 hours, then the computer will boot-up from initial state. Does anyone know the boot-up sequence?
Last night, I turned the AC switch to OFF then turned the ignition key to ON. Prius went through the boot-up but there is no screeching noise. This morning, I repeat the same procedure with AC OFF, same result as last night occurred without the screeching noise. Then I turn ignition to OFF and put AC on AUTO. After I turned ignition to ON again, there is boot-up sound but no screeching noise. Repeat with AC on AUTO again within 30 minutes, there is no screeching noise. There is a high pressure container for brake fluid in the area of the firewall on the passenger side. If I recall correctly, there were noises of fluid sloshing before the screeching noise. When starting the Prius with one foot on the brake, if the screeching noise occurs, I can feel vibrations from the brake pedal. But screeching noise can occur without pressing down the brake pedal. I will try later with just AC ON to see if screeching noise comes back and also with brake pedal depressed.
Drove 15 freeway miles then exit clover-leaf down-ramp right turn and screeching noise happened once. I tapped on the brake to slow down then left brake pedal untouched. While turning, the noise appeared. On return trip, clover-leaf up-ramp exit right turn did NOT generate the noise. On this forum, I found the brake actuator thread but it refers to Gen II Prius. Mine is Generation 1 Prius. Brake was flushed at 25,000 miles ago by Toyota Dealer. At that time, timing-belt, water pump, transmission fluid were all replaced (149,500 odometer).
Hold it hold it... how the blazes did you get your timing belt replaced? The G1 Prius uses a timing chain, it never needs replacing, almost under any circumstance. This was just as bad as the time a Toyota dealer insisted I change my power steering fluid. Prius has no PS fluid whatsoever, but at the time I fell for it, and paid for it too! I was a newbie to the world of Prius. Toyota Stealerships are amazing. As for screeching noise, I wonder if you have a hydraulic leak in the power booster? I wonder if you could trigger that noise in a hard panic stop and trigger the ABS. I wonder if it would cause that noise while the pressure is rebuilding. That would certainly cause the noise if it had anything to do with your braking system. Just a thought.
+1. Hi hksarmgor, Instead of doing hard panic stop, I suggest a simple test: 1) Turn the ignition OFF, depress the brake pedal more than 40 times. 2) Turn the ignition ON, check that the pump stops after 30 to 40 secs. Vincent
It was the serpentine belt. I mis-typed. And yes, one time the service adviser was going to write up a work order for change of timing belt for the Prius except the computer did not allow him to do it. Then he found out Prius uses timing chain.
Thanks mlibanio and vincent for your advise. I will try your test. Today, I tried twice to re-create the noise with AC in AUTO with no luck. But I can hear the brake reservoir being pressurized. That is also the location where I hear the screeching noise.
Try pump the brake pedals 40 times with ignition OFF (key out), then turn ignition to ON, AC is at AUTO. The pumping stopped around 28 seconds. There is no screeching noise.
Summarizing, brake fluid was changed 25,000 miles ago. Now there is intermittent noise. By far, the most likely cause is that there is air in the system. Take it back to the dealer and have them re-bleed everything.
Thanks Seilerts, the noise points to air discharging into the high pressure reservior. I will take my videos which captured the noise (2 with engine started and 2 without starting the engine) and show them to the dealer. If they then try to sell me on doing another brake flush, should I stand firm and insist on re-bleeding only? Of course they might charge me the same price as brake flush. The flushing was done on Jan 4, 2008. It was more than 3 years ago.
Hi there hksarmgor,have you by any chance tried checking the cv joints that are connected to the drive shaft?These joints are known to make such noises when the protective rubber boot is worn out.Kindly check and replace the joints if worn out.
