z06vettewannabe

So I'm taking my ZR1 in tomorrow to get it checked out, but was wondering if anyone can at least point me in the right direction for what is going on. 2009 ZR1, 19800 miles purchased 5 months ago. Lived its life as a show car, gently used, never tracked. Runs like a dream. About a month ago it began to start slowly and got worse. Went to Chevy dealer and diagnosed as starter. Starter gets replaced, problem fixed. That was last Friday. The next day I heard a strange noise under moderate acceleration only after the car was warmed up. Only for a second, but it was distinct. Didn't hear it the rest of the day. Next day, same thing, but now could make it happen any time under moderate acceleration. Cannot duplicate just sitting in garage revving motor, it only happens when car is loaded. So, here's the hard part, describing the noise. It sounds like a cross between belts rubbing and something like a wire rubbing against a fan. Relatively loud, sounds like it's from the right side of the motor. Hit the accelerator for anything more than normal cruising and "cack, cack, cack, cack", but that noise sped up a thousand times. Think of taking a fan and holding a metal wire to the blades, but I can't tell if it's a physical rubbing sound or something else. No power loss whatsoever. Acceleration never falters even a little, it just makes this nasty sound. Almost no weird vibrations either. My dad drove with me today and said he detected a very slight vibration, but very, very minor. Never happened even a single time before taking it to the dealer to get the starter fixed so my first assumption is that it has to be something they did. Any argument there? Not being a gear head and necessarily understanding how they installed the starter, is it connected to any belts and would they have to detension those belts and then retighten them? Apologies, trying to describe a sound might be fruitless. Any ideas or questions would help. Again, I am taking it to the dealer tomorrow to have a tech ride with me to hear the sound for himself. Thanks!

Nanook

Have you replaced your cats yet ?..just a stab here

ufaj26

since it did not start until the starter was replaced I'm guessing something may be touching the fly wheel under a load.

OnPoint

You might check the motor mounts.

z06vettewannabe

Thanks gents, good inputs. I will have these in the back of my mind when I go to the dealer today. The cats have not been replaced. The car is 100% stock, no mods. When I took it in the starter was replaced, I had them do an oil and filter change, a multi point inspection and there was as recall for a headlight low beam wire that needed to be replaced. If the only thing that was actually changed was the starter then in my mind it has to be related? I don't know. The other weird thing is that it only happens after the car has been warmed up and driven a while. Even when up to full temp, the first time I drive it, I can get on it and nothing, then I'll park the car for a bit, get back in and go and the sound is there.

09Z06pj

This is just another reason why I dread taking my car to a dealership for anything. Hope you get it straightened out and it turns out to be nothing major.

z06vettewannabe

Yep, I'm with you on that one. When I got the car I bought an extended warranty so I had no choice with the starter. I will say that the guy I've been dealing with at the dealership has been fantastic so far. When I brought my car in he really went the extra mile to make sure the car was treated well. He was very aware that the ZR1 is not a normal car, so I'm cautiously optimistic. I am pissed that I gave them essentially a perfect car, minus the starter, and now it's making a weird noise. I keep telling myself, "It's just a material thing, no big deal, and it will get fixed."

z06vettewannabe

All right, update. Took it to the dealer and went driving with their "Foreman", or lead mechanic.....essentially their most experienced dude. Learned a lot. When they replaced the starter they had to drop one of the cats so he's 99.9% sure it's a leak of some kind, either it didn't seal correctly or wasn't put back on correctly. That explains why it doesn't happen unless under moderate acceleration.....more back pressure, which after it heats up causes the sound. It's not something physically striking something else like I thought it might be, it's essentially mini backfires where the leak is. So it looks like no big deal and they'll go back in and check the cat to see where it is leaking, or wasn't put on correctly, or whatever. So Nanook......looks like you're the winner with the diagnosis. Thanks again for the inputs. This forum has always been extremely helpful whenever I've had issues.

ufaj26

Sounds like you have a good dealership to work with.

z06vettewannabe

I'll be the first to say that, while I'm not anti dealership, I've read enough horror stories to be on the lookout for anything that might resemble dishonesty on their part. I do think I got lucky. There's not a single hint of trying to pass this off on something other than what it is, a problem they created. They are going to fix it free of charge and are adamant it gets done right.

TurboRegal84

Cool of the dealer to put in the extra effort. Hopefully it is just a exhaust leak.