Strange sounds under load

**Nchristopherson** · 03-09-2014

Hey guys,

So I have been having this problem for quite a while, iirc it first appeared when I replaced the sway bar. Either that or the engine mount, I can't remember exactly. It was definitely before the engine had been opened up for performance modifications. It's kind of a grinding sound but it goes with the rotation of the engine. I really don't know how to describe it so I have a video here.

http://www.youtube.com/watch?v=xOw3tyVSmQE

You can hear the grinding 14-15 seconds

Any ideas what this may be?

PS. The video is 6 minutes long because I didn't know if my phone would capture the sound, so I tried to get it a couple times, but the first time is definitely it. Also, sorry about the exhaust leak. Don't have the skills or money to do a fab job myself and have no money.

Here's a list, to the best of my knowledge, of all the things I have done to this car: GMPP Sway Bar and end links, Struts, Hydraulic engine mount, outer tie rods, control arms, HAI, 3.4" pulley, SD Headers, VS cam, new timing chain and damper, #90 springs, retainers, valve seals, LIM SC TB FC and Front Head Gaskets, No tune but always scanning for KR.

**Scottydoggs** · 03-09-2014

turn the a/c on or defroster see if it still makes the sound. i cant really hear anything on the vid.

a/c clutch can make sounds when the a/c is off if the clutch is worn out, turn it on the clutch locks up and the sounds go away.

you can also take the belts off and spin all the pulleys to test for free spinning pulleys and smooth spinning pulleys.

**Nchristopherson** · 03-09-2014

Okay so I had the defroster on the whole time in this new video, but the sound was still there. I think that may be due to my a/c line pressure being too low, so the clutch won't disengage. This video shows a much more apparent example of the sound though.

You can really hear it when it shifts into the next gear. It's sort of a wobbly sound.

http://www.youtube.com/watch?v=GwvT-8-E6LE

**Scottydoggs** · 03-09-2014

if your a/c dont work the compressor clutch wont lock up.

start the car turn the a/c on, watch the a/c compressor, if its working the whole hub will spin ( the center part) when not on or not working only the outside part that the belt runs on will spin.

**Nchristopherson** · 03-09-2014

I did, I turned the AC on and watched for it to lock up and it didn't.

**Scottydoggs** · 03-09-2014

try spraying some lube in the clutch, the clutch bearings wear out and grind. when bad enough it can stop the engine from turning over.

**Nchristopherson** · 03-09-2014

Damn. SO I suppose my next step would be to take the belt off and check the pulley for free play?

Could a seizing AC clutch pulley cause the car to have a heavy idle and be sluggish when the wheel is turned back and forth standing still? I notice that happens too, so I figure the load by the worn bearings at idle may contribute to that.

Also, did the video make the sound more apparent?

**Scottydoggs** · 03-09-2014

i hear something not sure what it is. maybe see if you can rev the engine and catch the sound parked. hard to tell from in the car moving.

but yes if that clutch is bad it can put a load on the engine at idle, drag the idle lower. but i think you'd hear it at idle. it will sound like metal to metal.

seen a few lock up the engine or bust the belt. by lock up i mean it seemed like the block seized up, but the belt was holding it from turning over via a locked up a/c clutch.

**Nchristopherson** · 03-09-2014

Yeah, sorry for my loud exhaust lol, there's a leak at the catback. But the sound definitely doesn't happen parked. I have tried many times, it's only a thing when the car is rolling or beginning to roll. I believe it does it profoundly from a dig if the car is pointed up a hill.

My first guess would be something to do with the axles or their joints.

That sound couldn't possibly be the sway bar hitting against the downpipe, could it?

**Scottydoggs** · 03-09-2014

short of pulling the belts and looking for a bad pulley im at a loss.

fix the exhaust leaks, (they rob HP ) that will help i bet, as well as a tune.

**Nchristopherson** · 03-09-2014

Took the belt off and tried the compressor pulley - no hesitation.

**Nchristopherson** · 03-14-2014

Nobody has any idea?

**indygrandprix** · 03-14-2014

If you have the space and tools I'd put it up on Jack stands in the front and put it in D and see if you can see where it's coming from. Make sure you support it good, chock the wheels, and apply the parking brake.

**indygrandprix** · 03-14-2014

Also before you put it on Jacks try driving it a bit without the belt and see if you still hear the sound. Im assuming it's stillgoing to make the noise but it's worth a try

**Nchristopherson** · 03-14-2014

Update: Although I didn't try to put it on jack stands, I have noticed the sound is MUCH more apparent when turning. When driving in a straight line, the car has to be under a pretty good load to get the sound, but the sound will happen at any load when turning. I am starting to think it may be one of the axles going bad.

**Russosaur** · 03-14-2014

Axle or wheel bearing maybe. Before I did my wheel bearing it would always make noise when turning.

**Nchristopherson** · 03-14-2014

Doesn't a wheel bearing make a consistent noise when it goes bad? My friend has a bad wheel bearing and it reminds me of a card in the spokes of a bike wheel. The sound is matched to his speed and is consistent

**Russosaur** · 03-14-2014

Mine didn't, mine only made noise when turning. but I'm not sure

**indygrandprix** · 03-14-2014

It depends on the type of bearing. I've never heard of one sounding like a card in spokes. It usually will be a low growling noise. It'll sometimes just show itself when Turing and then all the time as it gets worse