Resolved- Update: High pitched whining noise & burnt smell 4.0L

Have 72k miles on my 2007 DoubleCab V6 4.0L.

Started the truck this morning & immediately heard a high pitch whirring or whining noise in the front end. Sounds like it is coming from near the alternator. Drove about 20 miles and heard the noise the whole time. Parked the truck and can smell a burnt rubber smell from that general location as well.

Sounds like bad bearings...should i focus on alternator & replace it or maybe could it be a pulley (idler pulley, etc)?

Anyone else have this problem, and if so what was the source?

Approx how much is an alternator and how difficult are they to replace on these motors?

Any help is appreciated. Thanks guys.

PS: the sound pitch gets higher as the engine revs. Sounds similar to bad power steering pump...but dont think it's that (based on location of sound & smell). Just sounds similar to what a bad power steering pump would sound like.

Anyone? Thanks for the help.

 

Alternator is easy to replace however, don't know the cost. I would guess around $200.

 

Remove the belt and check your pulleys too.

 

I'd check the idler pulley's before I'd check the alternator.

 

Or invest in an actual stethoscope, it works wonders actually.

 

Thanks for the advice, I will check all of these and report back with my findings.

 

Remove the belt and spin all the pulleys by hand to find the culperate. It will show itself right off. Don't assume anything. Replace the belt after you have replaced "defective part".

 

^^^This

 

show me this move to diagnos his pulley plz

 

Here's a preview:

 

When you want to find the origin of a noise, You can use a long screw driver between your ear (make contact) and a stable surface near the suspect bearing point (contact) the shaft will transfer the sound much better and you can really focus where you wan to check. Never touch moving parts in the process, ever.
I am betting the tension idler pulley is going bad and the smell is your belt burning up. I would not just replace parts until you fix it.

 

Laughed my ass off when I saw this! Thanks

 

You can also use a short length of garden hose.

 

details mofo

 

Update: Replaced all idler pulleys & noise was still there. Shredded a belt in the process, so replaced the serpentine belt as well, so we can rule that out.

Bought an automotive stethescope (should have done this first before a day of work & $100 on belts & pulleys but anyway).

Stethescope is telling me it is the air conditioner compressor pulley. The noise does not change when AC compressor is running or not...same noise either way, so i had originally ruled out the AC compressor as the culprit. However, the serpentine belt is still turning the pulley whether the compressor is actually running or not.

So my question now is, does anyone know if the AC Compressor Pulley is a replaceable part? I would hope i do not have to replace the entire compressor just because the bearings are shot in the pulley.

Anyone have any info there?

Thanks again for the help.

 

The pulley is not just a pulley, but a magnetized AC clutch assembly as well. $$$

You might be able to pull the AC clutch apart and source a new bearing. Sometimes carefully pulling the seal on the bearing and repacking with grease will buy you some time.

I've never attempted to rebuild an AC clutch but am interested in what you discover

 

You can buy a clutch and bearing or just the bearing depending on what is needed. Not sure of the part numbers.

 

Does the fact that the noise does not change at all (when the AC compressor is running or not) indicate anything with regards to me needing just the bearing, or the entire clutch and bearing?

 

Does the AC work? Are you hearing the compressor engage and disengage? If it does, the clutch is probably stuck engaged, and it's probably burning up the compressor. If it does not work, the clutch is not engaging or the compressor is already toast.

It's also entirely possible the AC is not your issue, but you say you have verified with the stethoscope....

 

Yes, the AC still works...blows very cold & it's 80 degress here. And yes, I can hear the compressor engage and disengage. So this would indicate the clutch is stuck engaged, is that what you are saying?

The stethescope has me about 90% sure the noise is coming from the AC compressor. I am placing the tip of the metal rod on the stationary bolts that hold the pulleys on. I have tested all of the various idler pulleys, alternator, power steering, etc and all of them make noise when using the stethescope, but the only one that is putting out that high pitched tone is the AC compressor, and the more pressure i put on the stetescope, the louder the tone gets. I'm fairly certain that is the culprit.