Thread: Whining noise coming from alternator maybe?

My 2004 GT has an annoying noise that makes it sound like @^%$, I thought it was perhaps a vacuum leak but after trouble shooting a little more, it seems to be coming from the alternator.

whenever i give it gas it gets higher pitch and it doesnt do it all the time.... I'm thinking it could be the pulley but i dont want to tear my car apart if its not that...

Has anyone experienced this?

its not a squeal or a screetch its just this high pitch noise that gets louder depending on how much gas i give it... when i let go of the gas it winds down... so i know its part of my belt system, just not sure what.

I'll try to get a sound clip

its not doing it now.... figures

Iv been told about that trick before, is there anyway to know if it the belt for sure? because im almost positive its my belt

I'll do the screwdriver trick, I know the difference between a belt squeal and this particular noise... a belt squeal is louder, and you usually hear it at idle mine can only be heard when i give it gas.

just a tip, Alternators do like to produce a high pitch howl\whine if a diode blows. This is because it is a 3 phase AC generator and a blown diode causes an imbalance. This sound will vary directly with RPMs. The faster you spin it the higher pitched it will get because your increasing the frequency its generating at. This sound SHOULD get louder with load. For example if you turn your headlights on the sound should get slightly louder.

As others have said the power steering pump is another thing that can do it.

I think you found my issue mrtube,

can you replace a diode? or does the alternator need to be replaced? if its repairable where can you find these diodes.

Typically people just swap it out for a rebuilt alt. I think the average rebuilt alt costs around $60-100. You will have to give them your old one.

However if you want you can try to find a new rectifier for it. Looks like a big heatsink with 3 screws. The rectifier contains 6 diodes that are not replaceable however the whole rectifier is.

I would recommend buying a rebuilt if you are not familiar with working on alternators. There are tricks you need to know to take one apart and reassemble it such as using a paperclip to hold the brushes in.

Check the level of your power steering fluid before you commit to the alternator. The reservoir is right behind the alternator and I also believe the pump is in that area too.

Reading on these forums, I've learned that a whine with low power steering fluid (or a bad pump) is a common problem on these cars, and I had the same problem, I thought it was the alternator or belts, but I checked and the ps fluid was so low it was barely reading on the dipstick. Topped it off and the noise is gone.

My GF works at a parts store and gets stuff at cost, I think I'll just get a higher output alternator with a lifetime warranty.
I plan on putting a nice stereo system in it so, less chance of alternator failure, thanks for the help guys

I'll check that out 1st friborage, my PS has been acting a littel different lately... never thought of checking it.

Now i know why I've never checked it.... the p/s reservoir is at a horrible place. i looked for about 5 minutes before i found it. and it is low....

Lionel : please let us know if adding fluid solves the problem or not.

Dont mean to hijack the thread, but do you guys know if the Prestone PS fluid is ok to use in our cars? I know some makes/models are picky about it, and the manual specifically says to use the GM fluid.

Yeah my 1st thought was the power steering fluid was low. I had this same thing happen to me a few years back, and I thought it was the alternator (even replaced the darn thing), until a wise man told me to check the power steering fluid. Sure enough, it was low. Added a little bit of fluid, and it has been fine ever since.

so, since nobody is saying anything about it, Im gunna assume it's safe? I dont have to go buy dealer PS fluid?