Howling noise on excelleration

[goofy02z06]

Hi all, it has been a while. So my 2002 zo6 makes a howling noise when I am moving and excelerating only. It doesn't happen when not in gear and I reve it up. Cordes has replaced the transmission,  tunnel bearings and clutch trying to eliminate the noise. I don't think it is the differential either. Could it possibly be the fuel pump under a load? I'm running out of things to replace and have no clue what the noise is from. It drives fine, no shaking or vibrations. Thanks in advance for any input. 

[Desertdawg]

At what speeds ?

Does it change with speed ?

Any particular area you hear it coming from ?

[old yeller]

My work truck at low speeds and turning would make that noise.

Turned out to be a left front hub bearing.

[Desertdawg]

Ha!  My work truck did it over 50mph, it was the wind blowing across the rung openings of the ladder up tup.

[goofy02z06]

It does it at all speeds, in all gears only when I push down on the throttle a little or a lot. It does sound like it winds up as the speed goes up. No clue on where it's coming from,  sounds like behind front seats but not real sure. At speed if I take it out of gear no noise, at speed and rev the engine nothing. At speed in gear if I'm not on the pedal nothing  it's only when I give it gas in gear. 

[Desertdawg]

Well that settles it. I’m betting on bad rear wheel bearing/hubs. 
 

You probably won’t get any wiggle out of them after jacking it up, the tolerances are very tight to begin with.
Try gently rotating the hub by hand to feel for any resistance or grinding. 
Or look for tale tale signs of black grease seeping out of the seal. 

[goofy02z06]

I'll give it a shot. Thank you

[Desertdawg]

Keep us updated, and pictures are a plus. 

[aenigma]

On 9/8/2023 at 3:11 PM, goofy02z06 said:

Hi all, it has been a while. So my 2002 zo6 makes a howling noise when I am moving and excelerating only. It doesn't happen when not in gear and I reve it up. Cordes has replaced the transmission,  tunnel bearings and clutch trying to eliminate the noise. I don't think it is the differential either. Could it possibly be the fuel pump under a load? I'm running out of things to replace and have no clue what the noise is from. It drives fine, no shaking or vibrations. Thanks in advance for any input. 

so did cordes give up? Or wouldn’t they have had a clue as to the issue? That’s confusing, you’d think they could’ve diagnosed it just hearing it. I know quite a few backyard mechanics who can hear and diagnose pretty accurately without throwing parts at it. 

[goofy02z06]

They just kept replacing stuff, clutch, transmission,  and tunnel bearings. I spent a ton of money and they have no clue what the problem is. I gave up on them I don't have that kind of money and replacing stuff was costing more than the car is worth. 

[goofy02z06]

Oh so I don't hear anything in the rear wheel bearing,  noise does not change when swerving. It only makes the noise when I touch the throttle. I would think if it is some kind of bearing I would hear it all the time. 

[aenigma]

Just now, goofy02z06 said:

Oh so I don't hear anything in the rear wheel bearing,  noise does not change when swerving. It only makes the noise when I touch the throttle. I would think if it is some kind of bearing I would hear it all the time. 

I agree.  We have had similar issues and it had to do with the rear end. My husband has built our race cars and that howling is annoying for sure so I know what you’re saying about it. 
I just really don’t understand though how they would replace all that stuff and they’re supposed to be skilled, and the same problem is there which was your chief complaint. Have they given you a reasonable explanation as to why you have all new stuff but you still have the noise? 

More importantly, have they apologized at least? 

[goofy02z06]

No, they have no clue what is making the noise. The differential is the only thing left to replace at another 5 or 6 grand. Any chance it could be the rear main bearing?

[aenigma]

2 hours ago, goofy02z06 said:

No, they have no clue what is making the noise. The differential is the only thing left to replace at another 5 or 6 grand. Any chance it could be the rear main bearing?

Husband says get it rebuilt instead of a new one. Don’t take it to a corvette place, take it to a differential place. Around $1500 or so. A differential place can diagnose it. And I would talk to whoever did your work that didn’t make a difference that you need your money back. 

[goofy02z06]

Thanks, know of a good place? And I wish I could get some of the money back. I spent a fortune there only to not have the issue fixed. 

[aenigma]

1 hour ago, goofy02z06 said:

Thanks, know of a good place? And I wish I could get some of the money back. I spent a fortune there only to not have the issue fixed. 

Husband says try Mesa Driveshaft.  Hes had good luck there and they’ve been around for a long time. 

[aenigma]

1 hour ago, goofy02z06 said:

Thanks, know of a good place? And I wish I could get some of the money back. I spent a fortune there only to not have the issue fixed. 

when I need normal work on my c7, I take mine to Network Automotive. They have been great for me. I do not believe that our cars are so special that they need special service and corvette only mechanics. A good mechanic can service as good as or better.  

[Desertdawg]

I agree with Mo, that’s a lot of extra expenses to not fix your problem. 
I wouldn’t say they need to give your money back, but I would be asking for either your parts back or the cash from them selling them for you. 

[Desertdawg]

8 hours ago, goofy02z06 said:

Oh so I don't hear anything in the rear wheel bearing,  noise does not change when swerving. It only makes the noise when I touch the throttle. I would think if it is some kind of bearing I would hear it all the time. 

That was my best guess. I would go the rebuild route with the rear end next. 

[aenigma]

10 hours ago, goofy02z06 said:

Thanks, know of a good place? And I wish I could get some of the money back. I spent a fortune there only to not have the issue fixed. 

That’s just horrible. Please insist on some type of reimbursement. That is really not fair and they are supposed to be experts. Anyone knowledgeable would have known what the issue is based on sound before replacing everything.  

[Chameleon]

Years ago I had a howl that occurred/got louder with acceleration.  It was the rear diff. Being on the pedal applies force to the diff, resulting in the howl. 

 

Beyond that, reading what you are going through with this makes me sick.  Been there/done that with a shop (Loud Pedal, now out of business) putting parts on my car that it didn't need while problems continued and my wallet got emptied. 

 

Cordes should have diagnosed the issue and explained the cause to you before replacing ANY parts. At the VERY least they should give your old parts back to you, and give you a full refund of all labor charges. 

 

I agree with the comments of taking it to a place that works on rear ends. I don't personally know one right now, but I do have an awesome shop on the westside that I trust...I will call them on Monday and ask if they can recommend a place specifically for diff work.  I will post up here what I find out.

 

AND...if Cordes doesn't step up and make this right to your satisfaction, I would give them a shitty Google review and complain to the BBB about your experience.  I am surprised they even touched your car, I have seen them turn away C5s as "too old."

[goofy02z06]

Thank you, I'm hoping someone can figure out what the issue is. I literally emptied my savings trying to get it fixed. I'm trying to build it back up enough to take it somewhere else to fix it. On top of all this they broke my glove box and didn't tell me. They rigged it to close and when I opened it, it fell apart. It was a cheap plastic piece that would have costed them nothing to replace after all the money I spent I still had to fix the glove box. Their excuse was "its plastic, they break all the time".

[goofy02z06]

3 hours ago, Chameleon said:

Years ago I had a howl that occurred/got louder with acceleration.  It was the rear diff. Being on the pedal applies force to the diff, resulting in the howl. 

 

Beyond that, reading what you are going through with this makes me sick.  Been there/done that with a shop (Loud Pedal, now out of business) putting parts on my car that it didn't need while problems continued and my wallet got emptied. 

 

Cordes should have diagnosed the issue and explained the cause to you before replacing ANY parts. At the VERY least they should give your old parts back to you, and give you a full refund of all labor charges. 

 

I agree with the comments of taking it to a place that works on rear ends. I don't personally know one right now, but I do have an awesome shop on the westside that I trust...I will call them on Monday and ask if they can recommend a place specifically for diff work.  I will post up here what I find out.

 

AND...if Cordes doesn't step up and make this right to your satisfaction, I would give them a shitty Google review and complain to the BBB about your experience.  I am surprised they even touched your car, I have seen them turn away C5s as "too old."

Thank you, ill look into finding a place to get it rebuilt. Any good shops in Peoria or West side of town?

[old yeller]

Try Arizona Differential Specialist ,2180 Grand Ave, Phoenix 602-462-5367.

 

***There is another shop with close to the same name in Phoenix that doesn't get good reviews***

[aenigma]

4 hours ago, goofy02z06 said:

Thank you, I'm hoping someone can figure out what the issue is. I literally emptied my savings trying to get it fixed. I'm trying to build it back up enough to take it somewhere else to fix it. On top of all this they broke my glove box and didn't tell me. They rigged it to close and when I opened it, it fell apart. It was a cheap plastic piece that would have costed them nothing to replace after all the money I spent I still had to fix the glove box. Their excuse was "its plastic, they break all the time".

Wow that’s awful. That sounds a little like Greg’s story with Bromleys. Very sad. Car people seem to end up learning what companies to trust the hard way.