Belt/Pulley Noise

I'm getting a rythmic thumping/humming sound (low pitched) that seems to come and go. Sounds worst at 1500rpms. No clue WTF it is. I know the coupler is going on the SC because I can hear the "rock tumbler" at idle and confirmed it's no good by spinning that pulley... LOT OF PLAY. So back to the other sound... I'm thinking balancer? Anyone have it go bad on them? Sound similar?

TIA

i have never personally experienced a failed balancer but i do remember hearing that they are pretty noisy. i dont exactly remember hearing that they make a thumping noise but definitely a whine. have you checked any of the other pulleys? or have you listened from under the car to see where its coming from? a few things to maybe check so you can get a good idea of where the noise is coming from unless you already know its in that area.

Mine was kind of a clunking noise you could hear constantly when you weren't on the throttle very hard. If you were WOT it was fine, but at idle or low rpm it would, chirp/clunk/click/ whatever you wan't to call it. At first I thought SC coupler, but my GF's dad said the 3.8L is common for the HB pulley and that turned out to be it.

When they start to go, they will wobble. The 2 halves of the balancer start to separate.

clink/clunk/clank/clanked/clignon/kink/kink/kink/kink/kang/kang/kang/kang/kang/kang

Sounds like the motor is blown,knocking,ect. sad shit i know.

When mine went on my Camaro it ran quite rough. It kind of felt like it had a lope. Eventually it would make a metal on metal scrape sound (scrape, scrape, scrape) that only happened at idle. I didn't know what it was, (I had just bought the car a few days prior) so I let it go, until it completely seperated and then it would just bong as it ran back and forth from the pulley to the timing cover. If it is bad, it can cause lots of stress on your crank, possibly resulting in failed bearings.

Heres what my 87 lesabre's sounded like. Not much to see in the vid, but the sound is there. Mine sounded like a diesel idleing!
https://www.youtube.com/watch?v=cpzGdvoWAbA

The sound is more like a "wub wub wub" that comes in every few seconds, goes away and then comes back. Sometimes it's louder under light load, sometimes it's louder at idle. It seemed loudest last night when the car was sitting idling in my friend's driveway. The driveway has a huge pitch to it. Any chance I'm looking at a bad motor mount? I don't think it's a bearing and I doubt the motor is blown. Changed the oil last night and it was perfect. Maybe a bad cam? I knew someone who had a series one 3800 where the cam went bad but it had different symptoms from mine. It would lose pressure in the gas pedal and act like it wanted to stall out.. and when you let off the pedal everything was fine again. I think it may have made a similar sound as mine... Hmmmm

Guess I'll just run it a while longer and see if I can pinpoint it.

Thanks for the suggestions guys. I appreciate it.

So I stuck my head in the engine bay this afternoon and the sound is very much apparent from the passenger side-which helped confirm it's either balancer or another pulley. At this point, I'm almost 100% sure it is the power steering pulley. You can feel vibration from that fender and hear the "wubwubwub" sound at the same time. Belt looks a little sloppy where it leads up to the alternator which again seems to suggest a lot of play in PS pulley. My car makes an odd grumbling sound on slow turns, which again, seems to suggest the power steering pump isn't all that great. I replaced all the idlers and tensioners so I don't think they are to blame. My car has always made this sound, it's just become way more noticeable in the past few weeks.

Anyone have this happen before? LOL If this is the issue, I'd be relieved. Going to have a buddy look at it this week to confirm.

If it's that bad, I'm surprised the shaft seal isn't leaking yet... However, try taking a length of vacuum hose and using it as a monaural stethoscope to see if you can prove your theory.

Could remove the belt tension and turn the PS pulley by hand. I will feel loose and not smooth if bad. I would expect more of a grinding/whining sound from a bad pulley. Maybe it's the PS pump itself that's making the sound?

By the noise you have described, it sounds like the balancer split to me. I could be wrong, but the only wub wub sound I've ever heard comes from something insulated....

I agree with you Scott but the odd thing is I'm seeing absolutely no play in that pulley. I guess if the rubber became separated, it could still spin and not show too much movement. Definitely get a lot of vibration in the cabin... especially the dash (been like that for as long as I've owned the car) and the vibration is now getting worse.

I can't imagine any of the accessory pulleys causing vibration in the cabin. You say this happens when in park?

A bad HB will clatter embarrassing loud while at a traffic light, no side to side play will be evident but when they are really bad you can manually rotate the belt about a inch back and fourth (as if the engine is easily turned) before it hits a stopper.

Removing the belt and playing with the HB is the best way to decide if still unsure.

AA wrote:

I can't imagine any of the accessory pulleys causing vibration in the cabin. You say this happens when in park?

I can actually hear the noise more now when the car is in park... almost morphing into a low pitched constant scraping/whining. There isn't much vibration in the cabin while the car is out of gear but if I'm sitting at a traffic light, the dash will vibrate quite a bit. The sound has remained the same while the car is driving. I'll hear that odd "wubwubwub" really quickly off and on. Sometimes seems worse at about 1500rpm. I was deathly afraid this was some sort of trans noise but the sound isn't evident from the driver side so I'm trying to rule that out. Still seems to be a pulley.

Thanks again for the suggestions. I appreciate it.

98inSFl wrote:

A bad HB will clatter embarrassing loud while at a traffic light, no side to side play will be evident but when they are really bad you can manually rotate the belt about a inch back and fourth (as if the engine is easily turned) before it hits a stopper.

Removing the belt and playing with the HB is the best way to decide if still unsure.

Ed-I'll try turning the HB tomorrow with the belts off to see what result. Thanks again.

Deekster was nice enough to send me a spare alt pulley he had kicking around. Put that in tonight and wouldn't you know... noise is gone 100%. Not only that, the odd vibration I was getting at 1500rpms (coincided with the noise) is gone. Car feels a lot better. Couldn't be happier now. Love the easy ones.

Thanks again Derek!!!!!!

Just the pulley, not the shaft/bearings??

The old pulley was warped on the outermost lip. I think the alternator was probably dropped on the pulley or possibly a manufacturing error. Either way, the belt which is pretty new was getting shaved down on the outside tooth and you could see the shiny spots where it was making contact with the pulley. I'll drive it around for the next few days to confirm the sound is gone but couldn't hear it at all last night.

DEMonte1997 wrote:

The old pulley was warped on the outermost lip. I think the alternator was probably dropped on the pulley or possibly a manufacturing error. Either way, the belt which is pretty new was getting shaved down on the outside tooth and you could see the shiny spots where it was making contact with the pulley. I'll drive it around for the next few days to confirm the sound is gone but couldn't hear it at all last night.

That makes sense. I had a delco reman alt from GMPD that come with a whacked pulley. I swapped it and sent it back on the core.

Albertj

^^ Ah so I'm not the only one! lol

It definitely needs a new coupler-luckily a local guy has a few kicking around. LOT of slop in that pulley but otherwise the car isn't making that odd noise anymore.

glad I could help out with leftover spare parts!!

Derek,
Did you end up using the oversize pulley from way back.?
If so, how did it effect the accessories during idle.?