2003 Blazer LS, 2wd, 2 door. After first starting, I can hear a noise coming from the altenator. I sounds like bearing's rubbing. It only happens when I am in park and reving the engine slightly. Between 1400-1600 rpm's. Above that the nosie goes away.

Also when the engine warms up, the noise is gone.

I had the altenator check at AZ and they said everything was O.K.

Of course, by the time I got to AZ the blazer was warm.

Should I start saving my pennies?

Many thanks in advance.....

 

When it's making the noise, shut the engine off and remove the serpentine belt. Start the engine long enough to see if the noise is still there. If the noise is still there, it's not any of the pulleys or their components. If it's gone, (shut the engine off) rotate each pulley and listen/feel for any noises. Post your results.

 

A bad serpentine belt, idler, or tensioner can mimic some much more serious sounding noises. None of the those parts are expensive either.

 

Thanks for the info. I was going to replace the belt anyway. So I will post results after doing that.

One question, a friend of mine said there was a possibilty of messing up the timing if the belt was not installed correctly. Is there some special attention I need to be aware of? Other the usual one of making sure it follows the diagram properly.

Thanks again

 

I can think of one way that would happen... somehow installed wrong, the belt shreds and knocks the crap out of the crank position sensor.

Otherwise, no. Unless your friend thought you were talking about a Timing belt {which the 4.3 doesnt have}.

 

I just had the same thing happen to mine. When cold it made noises, when warm it went away. Till it didn't My voltage out was fine but it eventually started making noise all the time. If I pressed on the pulley when running (not a recommended test) The noises went away. Swapped out the alternator and all is now good and quiet. The bearings in the alternator were toasted! New one would free spin easily old one wouldn't free spin more than 1/2 turn.

The bearings in an alternator going bad before the alternator it self going bad are rare, but it DOES happen!

 

Well, finally got around to taking things apart, after the noise got much louder yesterday. Took the altenator off and it was difficult to rotate by hand, let alone spin freely. At a certain point, about three turns by hand,
it was very difficult to rotate. Replaced it along with the bracket (broke at small piece holding the altenator) and everything is better.

Like another member posted, it might be seldom that it happens, but it does. Bearings went out before the altenator....

Thanks for all the help guy's....

 

Well.. NUTS!

I drive all hi mile cars. And havent had alt bearings fail me in 30 years.. at least.. prolly 600,000 miles total.

Yesterday I checked the free pulleys and found the tensioner needs replaced.
I spun the alt and it only spun about three turns seemed a little stiff. Didnt think anything of it, quiet and no slop.
After reading this went out and spun a spare ford alt and it went about five and not stiff.

meh!