[Marvinn]

I'm hoping someone has a cure to stop the madness: My daughter's 2011 Pilot (115,000 miles) started chirping under the hood a few weeks ago. A mechanic diagnosed the issue as a belt problem, then replaced both the serpentine and alternator belts. Almost immediately thereafter, the chirping returned. A second mechanic agreed with the initial diagnosis, but indicated that the wrong serpentine belt was installed; I'm not sure whether he meant wrong brand or wrong size. He then installed a 6PK2135 belt. Unfortunately, the noise continues.

The noise begins immediately when the car is initially started in the morning and continues all day. It begins as a chirping sound, grows quickly into an ear-piercing shriek, then fades away when the car completely warms up (e. g. highway speed). After parking / cooling down, the cycle / noises return when the car is started again.

Thoughts and solutions would be greatly appreciated!!

 

[thefisch]

I would check the tensioners for timing belt and accessory belt. The tensioner is known to make more noise when cold. Look up videos online and see how the sound compares.

 

[alzeal]

I second the tensioner, once its warmed up and the noise has stopped, spray some water on the belt to see if the sound comes back. If it does the tensioner is worn and not putting enough tnesion on the belt.

Btw this is for the serpentine accessory belt. A worn pulley for the timing belt will usually make a grinding noise and will not go away after warmed up. Timing belt is also toothed so it doesnt slip. Screeching sound when cold is almost always from a slipping belt.

 

[slipjohn1]

Could be the tensioner. Back in the day that sound meant alternator was going bad. It's definitely a bad bearing noise of some kind. Go with tensioner first.

 

[Marvinn]

Thanks, all, for the good suggestions. We'll follow your advice and see what happens. I'll report back when the noise has been eliminated!

 

[STMech]

Could be the tensioner. Back in the day that sound meant alternator was going bad. It's definitely a bad bearing noise of some kind. Go with tensioner first.

Could very well be the alternator front bearing. Carefully check with a mechanics stethoscope to verify.