Whistling/Whining Sound Fluctuates with RPMs

[Schimpfy]

Please excuse me if this has been posted about before, but I couldn't find an answer. Maybe I'm just not searching the right thing.

Anyway, my truck started making an odd whistling/whining sound that fluctuates with the RPMs. At idle it's not noticeable and above 2,500ish RPMs it tends to disappear. If I rev it a bit when the noise occurs it goes away for a few seconds, but comes right back. Some advice I'd found online said it might be the alternator. I went to AutoZone today and had it tested and it checked good, however, I noticed that if I spun the pulley it had a slight squeak and it was binding a bit. I decided to replace it.

The. Noise. Is. Still. There.

I'm at a loss because it's not being consistent when I'm searching for where the sound is coming from.

 

[SCOTTYINWV]

Check all of the rest of the pulleys for play. And it could be from an intake leak or a leak in the air box or tubing. Make sure all if that is tight.

 

[SAATR]

Here's a little procedure for you:

First, remove the belt entirely and start the truck. If the squeak/whine is gone, you can be certain that it's coming from something driven by the accessory belt. If it's still present, look elsewhere.

If the noise is gone, it's time to track down its source. After you reinstall the belt, get a can of brake cleaner and a helper and start the truck. Have your helper hold it at the RPM where the noise is present, and use the brake cleaner with the straw installed to spray the bearing area of the idler and tensioner pulleys. Keep clear of the belt, fan, and pulleys! If the noise momentarily goes away after you spray the bearing, you have found your culprit and should replace it. If not, try the AC compressor in the same manner, spraying the clutch and bearing area. If the noise disappears, your clutch is the source of the issue and may need to be replaced. If you have no luck there, it leaves the PS pump, water pump, or possibly one of their pulleys. Inspect all grooved pulleys carefully. The bottom of the grooves should not be shiny. If they are, then the pulley is worn and is allowing the belt to ride in the bottom of the pulley instead of on the sides of the ribs. The only solution for this is to replace the pulley. This is usually what's wrong in situations where a new belt will quieten or eliminate the noise, only to have it come back days or weeks later. And, last but not least, if all else fails and you can't find a faulty component or bearing, try a new belt. Most modern designs from quality manufacturers like Dayco, Gates, and Goodyear are built to help eliminate noises and squeaks caused by slightly worn or misaligned pulleys. A whine from a power steering pump will usually worsen when you put a load on it. Turning the wheel back and forth slightly may exacerbate the whine and help you track it to its source. Good luck!

 

[someotherguy]

Tough call without hearing it in person but don't overlook the possibility of a vacuum leak, especially since you say it goes away momentarily when you gas it. Vacuum drops at that moment.

Regarding the alternator it's normal to notice a tiny little bit of squeaking when you turn them by hand. I've noticed that on a bunch of them that operated normally otherwise.

Richard

 

[JollyGreen]

Here's a little procedure for you:

First, remove the belt entirely and start the truck. If the squeak/whine is gone, you can be certain that it's coming from something driven by the accessory belt. If it's still present, look elsewhere.

If the noise is gone, it's time to track down its source. After you reinstall the belt, get a can of brake cleaner and a helper and start the truck. Have your helper hold it at the RPM where the noise is present, and use the brake cleaner with the straw installed to spray the bearing area of the idler and tensioner pulleys. Keep clear of the belt, fan, and pulleys! If the noise momentarily goes away after you spray the bearing, you have found your culprit and should replace it. If not, try the AC compressor in the same manner, spraying the clutch and bearing area. If the noise disappears, your clutch is the source of the issue and may need to be replaced. If you have no luck there, it leaves the PS pump, water pump, or possibly one of their pulleys. Inspect all grooved pulleys carefully. The bottom of the grooves should not be shiny. If they are, then the pulley is worn and is allowing the belt to ride in the bottom of the pulley instead of on the sides of the ribs. The only solution for this is to replace the pulley. This is usually what's wrong in situations where a new belt will quieten or eliminate the noise, only to have it come back days or weeks later. And, last but not least, if all else fails and you can't find a faulty component or bearing, try a new belt. Most modern designs from quality manufacturers like Dayco, Gates, and Goodyear are built to help eliminate noises and squeaks caused by slightly worn or misaligned pulleys. A whine from a power steering pump will usually worsen when you put a load on it. Turning the wheel back and forth slightly may exacerbate the whine and help you track it to its source. Good luck!

Phenomenal explanation Travis. My first guess was the idler pulley without hearing it.

 

[AirmanSkee]

Most likely idler or tensioner pulleys.

Does it sound like this? (Don't mind the crappy exhaust sound... obviously the pipes are in the wrong location to work )

http://www.youtube.com/watch?v=2Rm1NbgYFU4

 

[t93k2500]

When my distributor was on its way out there was a slight wine throughout the powerband. I could also feel it on the cap itself while it made the noise. Turned out to be some serious play in the shaft.

 

[Schimpfy]

Most likely idler or tensioner pulleys.

Does it sound like this? (Don't mind the crappy exhaust sound... obviously the pipes are in the wrong location to work )

http://www.youtube.com/watch?v=2Rm1NbgYFU4

This...almost exactly, but the whine wasn't quite that loud. Prior to reading everyone's responses I pulled the tensioner and idler pulleys. Both of them were shot, but the tensioner was way worse. R2 both pulleys and life is good.

Scotty, yours was the one post I was able to read before the site went FUBAR earlier and you got me going in the right direction.

SAATR, those are some great troubleshooting steps and if I hadn't already id'd the bad parts I'm pretty sure I'd be following your instructions. Well written.

Thanks, guys!

 

[AirmanSkee]

No problem! I was going to tell you if that's it then I replaced both pulleys and dropped the whineB! Haha mine is pretty loud. When I did my Burnout contest, some people asked if it was charged because the whine haha

 

[JD4440]

When my distributor was on its way out there was a slight wine throughout the powerband. I could also feel it on the cap itself while it made the noise. Turned out to be some serious play in the shaft.

How long did it make the noise before you repaired it ? My 97 has been intermittently making a fidgeting sound from the back side of the motor for a little while now. Checked it out last weekend and placed a stick against the cap and you could feel the vibration pretty good while it made the noise. I have one with around 80-90k on it I'm going to try. Mine has 230k on it.