Knocking sound from alternator

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BILL228

Discussion Starter · Apr 16, 2010

Just thought I would share my recent trouble with my Caliber. About 2 weeks ago I noticed a small knocking/ringing sound (it sounded like a diesel engine). At first it would only make this sound when the car was running for an extended period of time, maybe 30 minutes+. Checked all the fluid levels and everything was fine. The sound was coming from the serpentine belt area but it was just too hard to tell what was making the sound. Took the car to Pep Boys and they said it was either a power steering pump or an alternator going bad. Took it to the dealer to see if it was covered by waranty, and I found out my waranty ran out at 36K (odometer is at 52K right now)

. The mechanic told me it was gonna cost me $680 to put a new one in. I respectfully declined and took it to my father-in-law's mechanic who said he would do it for $250 INCLUDING labor! Just got the car back a few days ago and it sounds better than ever. I wish I would have recorded the sound on a video or something because it was absolutely HORRIBLE. If anyone has any insight as to why an alternator would wear out at 52K miles, please inform me. And if anyone thinks they have the same problem, send me a video w/sound so i can try and compare it to my sound. Thanks!

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Flyinghigh

· #2 · Apr 16, 2010

I've heard of a few other people having premature alternator failure. I think there may have been a bad batch of bearings. Usually an alternator will last a hundred thousand miles or more before even needing brushes. Most of the time it's either a bearing or the brushes that go bad and not the armature or commutator. Did they specify what exactly was wrong with it?

BILL228

Discussion Starter · #3 · Apr 17, 2010

Yeah, they said the bearing was wearing out. Guess I got one from the bad batch. Thank you for your insight Flyinghigh:smileup:.

Flyinghigh

· #4 · Apr 17, 2010

You're welcome. I don't know that I'd call it insight, I just spend a lot of time one the forumZ. LOL

LilStacy08

· #5 · Aug 9, 2010

OMG I am having this SAME problem. I described it the same way to my husband, too... that it sounded like a deisel LOL. Actually, I'm not LOLing, my Caliber is at the place right now getting a new alternator... $600something

Excaliber07

· #6 · Aug 9, 2010

LilStacy08 said:
OMG I am having this SAME problem. I described it the same way to my husband, too... that it sounded like a deisel LOL. Actually, I'm not LOLing, my Caliber is at the place right now getting a new alternator... $600something

$600 seems awful steep for an alternator, I would have got an estimate from somewhere else.

Flyinghigh

· #7 · Aug 9, 2010

I agree with Glenn, I think you got taken advantage of and didn't even get kissed first!! They probably would have given you husband a lower price.

JoseRT

· #8 · Aug 24, 2010 (Edited)

i will be posting soon, on how to install/remove the alternator!!! mine sounds BAD but BAD, just like the video from this site!!

LOUDERMAN

· #9 · Aug 25, 2010

The alternator doesnt look like it would be incredibly difficult to pull out. But I'm sure some pictures would definatly help!

TheCoonHound

· #10 · Aug 28, 2010

The clunking sound on the alternator is from the pully, it has a over-running clutch system on it that wears out all the time, Caravans are famous for it, I change them all the time. Oh and changing the alternators on our car is a bitch, you have to move the A/C compressor out of the way first. I have done a few at work now and am pretty fast at it now but it still sucks.

C-Ya!

DKazoroski

· #11 · Aug 28, 2010

TheCoonHound said:
The clunking sound on the alternator is from the pully, it has a over-running clutch system on it that wears out all the time, Caravans are famous for it, I change them all the time. Oh and changing the alternators on our car is a bitch, you have to move the A/C compressor out of the way first. I have done a few at work now and am pretty fast at it now but it still sucks.

C-Ya!

Interesting - Chrysler calls that thing a decoupler pulley.
What purpose does it serve?
Most car alternators have the drive pulley directly bolted to the shaft.
why does Chrysler need to be different?

DKazoroski

· #12 · Aug 28, 2010

Just found the answer - it helps smooth out the torque load on the belt system, supposed to make the belt and other parts of the belt drive system last longer.

Seems as if they are on an awful lot of modern cars - almost required when a spring type belt tensioner is used - saw some video - look up decoupler pulley - you can see it too.

DKazoroski

· #13 · Aug 28, 2010 (Edited)

What the issue is:

The alternator has the greatest rotating mass of all the driven components in the belt system. This means that it does not like to change speed rapidly (I. Newton)

The engine puts out its power in pulses, which cause slight increases (each power stroke) and decreases of crankshaft RPM even if the engine is running at a "constant" speed.

The decoupler pulley, prevents these pulses from going through the belt back and forth to the alternator, so the pull on the belt remains more constant. Without the clutch, the pulsations become very large, and cause the spring tensioner to wildly swing from one end of travel to the other.

So - an expensive pulley/clutch assembly is used to protect a low cost belt and tensioner setup. Where is the logic here? Must be somewhere, or something that is not readily apparent.

As coonhound posted, and from what I have read, failure of these clutches is somewhat frequent - this clutch is almost always the cause of knocking or rattle coming from the alternator.

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Reactions: 1

DKazoroski

· #14 · Sep 4, 2010 (Edited)

An update:

The decoupler pulleys are available from NAPA for about $80.00. Might be a lower cost fix for the more mechanically inclined.

collegegreen

· #15 · Oct 29, 2010

BILL228 said:
Just thought I would share my recent trouble with my Caliber. About 2 weeks ago I noticed a small knocking/ringing sound (it sounded like a diesel engine). At first it would only make this sound when the car was running for an extended period of time, maybe 30 minutes+. Checked all the fluid levels and everything was fine. The sound was coming from the serpentine belt area but it was just too hard to tell what was making the sound. Took the car to Pep Boys and they said it was either a power steering pump or an alternator going bad. Took it to the dealer to see if it was covered by waranty, and I found out my waranty ran out at 36K (odometer is at 52K right now) . The mechanic told me it was gonna cost me $680 to put a new one in. I respectfully declined and took it to my father-in-law's mechanic who said he would do it for $250 INCLUDING labor! Just got the car back a few days ago and it sounds better than ever. I wish I would have recorded the sound on a video or something because it was absolutely HORRIBLE. If anyone has any insight as to why an alternator would wear out at 52K miles, please inform me. And if anyone thinks they have the same problem, send me a video w/sound so i can try and compare it to my sound. Thanks!

I am having the same problem with mine but the sound is not that bad. Bearing is out, about 61000 miles, cost $300 including labor with lifetime warranty. Great car, I love mine.

collegegreen

· #16 · Oct 29, 2010

Mine just started doing the same but sound is not too bad though. 61,000 is too early for the bearing go bad but sounds like a common problem for Caliber. $300 cost including labor with lifetime warranty. Great car but some annoying minor problems.

Flyinghigh

· #17 · Oct 29, 2010

Thanks for the information, Dave. If mine starts that crap, I'll fix it myself. I'm a cheap, er, I mean a frugal person. LOL I just finished putting struts and shocks on my Grand Caravan for about $130 bucks. Shops around here wanted a minimum of $700. I won't pay anyone to do something I think I can do myself.

Smit0002

· #18 · Nov 11, 2010

Does anyone have a video of this issue? Mine makes an awful sound from the pulley area so do to my mechanics request I have replaced the AC compressor, tensioner pulley, and the crankshaft pulley... I would post a video on what it sounds like if I only knew how. I will describe it as best as I can. To me it sounds kind of like something is loose and vibrating. It does it at a low idle or when there is a slight pull on the motor (having my ac on, or starting to turn the steering wheel while not moving or sitting at a stop sign idling) Soon as I rev the motor or give it some gas the rattle sound goes away. Does this sound like the issue with the alternator or something else? Any ideas? I will post a video as soon as I figure it out!

Francois

· #19 · Nov 11, 2010

Smit0002 said:
Does anyone have a video of this issue? Mine makes an awful sound from the pulley area so do to my mechanics request I have replaced the AC compressor, tensioner pulley, and the crankshaft pulley... I would post a video on what it sounds like if I only knew how. I will describe it as best as I can. To me it sounds kind of like something is loose and vibrating. It does it at a low idle or when there is a slight pull on the motor (having my ac on, or starting to turn the steering wheel while not moving or sitting at a stop sign idling) Soon as I rev the motor or give it some gas the rattle sound goes away. Does this sound like the issue with the alternator or something else? Any ideas? I will post a video as soon as I figure it out!

Maybe this link can help:
http://www.caliberforumz.com/showthread.php?t=32968&highlight=alternator

Smit0002

· #20 · Nov 11, 2010

Thanks Francios! I sounds similar to the first video but I am not experiencing anything else that guy is but I will try posting a video of it tomorrow when its light out.

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