So I've been hearing this noise from the engine compartment i can't really describe it sounds like a pully maybe because reving the engine it's no noise so i don't know but it has me kinda worried. I hear it more at idle and not sure it's engine or transmission. I made a video but not sure how to upload. Took it to a shop today they say it may be a drive pully but not sure saying maybe crankshaft pulley

 

having trouble figuring this out i went to 2 shops and one said its the crankshaft pulley, the other shop said its coming from bottom of motor and its internal. Another person said sounds like a pulley also, so im stumped

 

 

Yes thats what the last mechanic i went to yesterday told me to do because the noise was not coming from the motor itself. Thats why it pays to get more than one opinion when trying to diagnose things.

 

Update: I pulled the a/c and alternator belt off the car and started it up. It ran quiet as a pin drop. Changed idle pulley, so it's not that. So now I've narrowed it down to possibly alternator making the noise. It's like a loud hum and sometimes a whine. Also crank shaft has a slight wobble but it's not making noise.

 

If the AC isn't on, the AC clutch isn't engaged so the pulley would spin freely. You can bypass the AC with a shorter belt (search the forum for details) that should help you confirm it isn't the AC.

I was chasing a similar noise and replaced my a/c clutch bearing (wasn't it). Then replaced my alternator, which seemed to (almost completely) eliminate the noise.

 

Ok good idea man I'm gonna try the shorter belt if Napa carries it.

 

Same thing happened to me, a while back.... No A/C for now...... If you need the belt number let me know, still have it in my tool box

 

Yeah i need the belt number please.

 

No A/C in FL!? Damn man, you're a trooper.

 

Ok guys I narrowed it down to the alternator making the noise. I bought the a/c bypass belt from O'Riley's it fit perfectly size is 37.5 gates part number 6pk929/k060365. Thought it may have been the AC compressor but it's alternator.

 

What model year alternators fit our cars

 

that's pretty sad that a mechanic can blame internals of the engine when real culprit is alternator. Good for you for figuring it out. That was beyond terrible for him to say that.

 

Update the noise just got so bad I could not take it anymore. Loud hum, kinda metallic sound at times, and whine, also power loss ect. So I ended up replacing the alternator myself. I was afraid to do it because I've never done it. I paid someone to replace the alternator last time lol. Pretty easy to get off the car and I didn't have to remove the idle pulley assembly. Hard part was getting it back in and lining the bottom up to get the screw in. Long story short the car is running great no more noise. I'm amazed at how much noise that thing was making yet still running. If you didn't know any better you would think it was engine related

 

dude i am having the same exact noise and situation, car drives fine, no codes, no drivability yet, i apprecaite you following up in your own thread ! thank you. i will post back and see if this whinning, moaning was the alternator in my case, it honestly seems electrical like noise so it makes sense it could be the alternator. been 6 something years so since last replacement.

 

Wow, this is crazy. I think I've developed the same noise also. The last 2 times I've started the car "cold" (it was about 90F outside), there was a whine coming from under the hood that goes up in pitch as you rev the engine. It almost sounds like a slipping belt, but not really, it sounds more metallic/mechanical. I agree with Prophecy99 it almost sounds like engine whine that you can hear through your speakers if you have a ground problem, but it definitely is not that in this case. However, after driving for a couple minutes, it goes away. The fact that it goes away after the car warms up makes me think it may not be the alternator. Anyone have any other ideas?

 

Start by looking at the alternator. Use a stethoscope before the noise goes away. You can get a stethoscope at Harbor Freight for $4.99. Easy peasy.

 

Good idea. I'm going to head over there today. Thanks

 

i have my car at the shop today, i will keep you posted, and i must say , at first glance it does "feel" like the noise goes away but it does not in my case, it is just covered by the higher road noise and engine etc. but if you coast down a hill at that higher gained speed the humm/whine is still definately there but lower because no rpm, obviously coasting it dampens the whine/moan w lowered RPM but its definitely present.

i have drove about 3 hours (approx 130 miles) over 3 days with this symptom, highway speeds, traffic, back roads, hills, morning evening. short trip long trip. it did not go away any of those times.

 

update: shop called and it was the alternator making all that noise !, it hurt my newer battery too, new 750cc , reading 715cc. but all good I am happy that is all it was ! if you hear rc car like humming and moaning, its probably the alternator.

 

Figured it was the alternator. Glad you got it figured out.

 

Thanks for the update.

I'll have to check this. I can clearly hear it under the hood when the car is cold. After a few miles, when it appears to have stopped, I'll get out and open the hood and see if the noise is still there.

Just curious, did they tell you how the alternator was actually performing electrically? It would seem that the noise was probably from the bearing being worn out. If that was the case I would think the alternator would still charge correctly, but just make a lot of noise in the process. If it was the brushes inside then that's a different story. Obviously, it needed to be replaced in your case, but it would be interesting to know if it actually wasn't generating the correct amount of current.

Also, your battery may not be compromised. if you test it a few more times, you'll probably get substantially different results. I have a pretty good tester and I consistently see CCA readings vary quite a bit.

Do you know what alternator they installed? I was surprised to see Rock Auto has a new alternators for our cars for $100 - $150.

I was unable to get a stethoscope yesterday, but the sound definitely appears to be coming from near the alternator. I'll be able to confirm this soon.

 

they told me about the voltage not being good and how that was some of the reasoning behind the diagnosis, don't remember numbers sadly. and also i tried prying as to what type of alternator they were gonna put it but just said they don't have too many issues with their "aftermarket" parts. i mentioned there are no new ones any more, etc etc. and i actually went to rock auto today as well and they have plenty to choose from, and supposidly new ones which makes no sense.

i did look up when i last did my alternator, and it was november 2013 and it was a $323 reman from napa and $170 labor to install. - this one is supposidly $200 reman from their vendor, and $300 to install =/.. lets hope this one last 7 years like the napa reman one.

 

OK. Well the good thing is that it wasn't something major and you're back in business.

Edit:
I put a stethoscope on my idler pulley and it was obviously toast. I replaced the pulley and all seems to be good now.

 

Glad you found out the problem!

 

thanks maxinout93 ! you have provided many helpful posts, knowledge and experiences. very helpful