Z06Vette.com - Corvette Z06 Forum - metalic tapping noise 2-3K RPM

zeta08 · 04-19-2008, 07:10 PM

I have 1400 miles on my 08 Z and I have a new noise that is worrisome and bugging me... Sounds like a random metallic tapping sound, like an exhaust heat shield sound, but very short and soft, and not a rattle. It actually sounds sort of like a detonation (92oct), but in a random fashion averaging one per second. It is heard loudest at 2-3K RPM, even in neutral, clutch in or out, heard loudest near the glove box. I hear it when driving and at rest, speed is irrelevant. But for example at 75mph in 6th or 3rd, it is very soft, because the revs are too low or too high . When I pop the hood, my wife hears the sound in the cockpit at 2K rpm, but I hear nothing unusual under the hood! Sounds perfect. Is this NOT a heat shield? I searched on the forum and can't find the noise described. It's not the diff or clutch noises, I hear them too, I think. Car runs perfectly...I have read here before of a shifter rattle.?? Any insight? Please? Thanks.

IT L GO · 04-20-2008, 05:04 AM

I found this on another forum this might be it.

Some of the LS7 engines are becoming plagued with a dry sump oiling system noise that mimics a rattle sound, coming from the right dash board area, and it's enough to drive you cuckoo.

GM actually tried to say it was normal, a byproduct of the LS7 engine (ear plugs included) LOL

GM says attempt NO fix at this time as it would be an admission that there is a problem and don't suggest a fix to the customer, they don't want it known there is a real problem, and they have NO FIX for it yet.

Also see this thread
Rattle FIXED!!!

Also Post 14# from this thread
Brand New Z06 - Help!! - Corvette Forum

zeta08 · 04-20-2008, 07:49 AM

It L Go, Thanks! The sound described below is exactly the sound I hear..Saved me from uselessly changing the oil (today!) before a sump exchange...I can print this out and go to the dealer and save everyone a lot of time..Below is the first post from corvette forum then his followup. I will post a followup myself to confirm this was the sound and how they fix it.

from: Brand New Z06 - Help!! - Corvette Forum
>>
I took museum delivery on the 14th of my 2008 Z06. Absolutely love the car, but after 700 happy miles, I think I have a problem. About 50 miles ago the car started developing a popping noise that appeared to be coming from behind or underneath the dash on the passenger side. It’s most pronounced around 1800-2200 rpm. It kind of sounds like popcorn in the microwave, but not as loud.

I’ve spent the past two days driving myself crazy trying to find the cause of the sound. It’s too loud to be a relay and it’s definitely not coming from the fuse panel. I’ve listened everywhere inside the car. I’ve even used a stethoscope. I think the noise must be coming from outside underneath the car and yet I can’t even hear it with the hood open and my ear to the engine bay.

My best guess is it’s coming from the exhaust system – Specifically, the catalytic converter /s and the design of the car amplifies the sound and makes it appear as though the sound is coming from underneath or behind the dash.

I know. . . It seems like a stretch, but it sounds very similar to the noise the exhaust system and catalytic converters make when you turn the car off (popping and clicking sound) as the exhaust cools.

I’ve filled up twice at different stations and the sound is still there, so I’ve ruled out bad fuel.

It’s definitely not the drive train or differential because the sound is still present when the clutch is depressed and/or the car is not moving.
=====

Sorry took so long to get back to you guys – Well… the dealer did a hell of a job finally isolating the noise. It turned out to be the oil tank (Z06 dry sump system). There's a small tubular screen at the bottom of the tank that came loose and was rattling/vibrating in the tank.

Now that's one for the books! - Couldn't find anyone else with a similar problem. I have heard a few complaints of noise behind the passenger side dash and the dealer telling the individual it's just a relay. If the noise is pronounced (louder than a typical relay) and the car is a Z06, I suggest you check the oil tank.

It's incredible how difficult it can be to isolate a noise - Even with a stethoscope it took the dealer several hours to find it - No BS, I was there watching!

Most importantly, it was the best dealer experience (dealer name OMITTED) I've ever had! I didn't even buy the car from them and they treated me like a lifelong customer.

I recently retired from the Army and settled in Decatur, AL. I have to say there's something to be said for how people treat you in a small town.

It was a very easy job (swap tanks) and I got that 1000 mile oil/filter change out of the way

allanlaw · 04-20-2008, 11:59 AM

There was another report ('08) on the CF involving the replacement of the tank because of the screen self-destructing. Unfortunately, the owner still has an undiagnosed knocking noise

zeta08 · 04-23-2008, 08:15 PM

I was told today that my oil sump can is indeed the source of my noise. 3 parts are on order. other info:

there is a TSB on this per my dealer

there is no mention of damage beyond the oil can (OK to drive until fixed?)

Any idea what the 3 parts to fix it are? I don't have any idea if they are fixing it or replacing it.

I want to thank It L Go for the info, it seemed to really help sort things out and helped me stay sane. THANKS.

zeta08 · 04-30-2008, 06:01 PM

Oil can was the source of the noise. Replaced under warranty at 1500 miles. (Feb 08 car production date).

dvredc6427 · 05-04-2008, 09:13 PM

I'm a member of this strang noise too - NCM delivery 5/1 and mine started at about 50 miles! I'm also new to this forum and this is a perfect example of just how benefical it can be. This noise was driving me nuts because I thought it was coming from the dry sump container but felt no way it could be that, not after just 50 miles into my trip home! If anyone has the TSB on this please let me know so I can bring the info to my local dealer.

Otherwise my new 08 427 is awesome! #011

Thanks!

zeta08 · 05-05-2008, 07:54 PM

I just printed out the long added post on this thread and brought it in, they found the bulletin, heck, if they can't find their own bulletins I wouldn't go to that dealer! The car is perfect now, as yours will be soon...

dvredc6427 · 05-05-2008, 08:42 PM

FYI - I called my local dealer who appears to deal in a pretty high volume of Vette sales and Z06's too but they gave me a scare and said IF my diagnosis of it being the dry sump container the oil pan would have to be dropped too. I said that didn't makes sense based on what I had read here in the forum and if the problem is in the tank why disturb the original seal on the oil pan? Sounds to me like this dealer doesn't know about the problem and/or wants to make more of it than necessary. Has anyone else had their dealer do the oil pan drop (I assume to check for any loose parts from the can) or has everyone just had their dry sump can changed?

Thanks,

Del

zeta08 · 05-06-2008, 08:37 PM

Quote:

Originally Posted by dvredc6427

FYI - I called my local dealer who appears to deal in a pretty high volume of Vette sales and Z06's too but they gave me a scare and said IF my diagnosis of it being the dry sump container the oil pan would have to be dropped too. I said that didn't makes sense based on what I had read here in the forum and if the problem is in the tank why disturb the original seal on the oil pan? Sounds to me like this dealer doesn't know about the problem and/or wants to make more of it than necessary. Has anyone else had their dealer do the oil pan drop (I assume to check for any loose parts from the can) or has everyone just had their dry sump can changed?

Thanks,

Del

I really don't think they have to remove the "oil pan", which is sort of a misnomer anyway isn't it? There really is no oil pan just an engine bottom cover? I don't know. But I do know that I don't think they did that to mine and I can tell you it is doing fine now after the oil can was replaced.
I will say that the info I came in with and gave to the service manager, he said, was very helpful. The SM also said that the bulletin doesn't say to stop driving, and told me I could drive until it was fixed. His words, not mine, but doesn't that imply that GM thinks there are no broken parts in the bottom of the engine (which would have to go through the oil tank hose to the engine as well)?...I think the engine is not involved.
I agree with you, I don't think the engine should be cracked open unless they really think there is something wrong there separately. But I know, It's hard coming from a position of assumed ignorance and definite lack of power and authority...
I will say, I insisted to myself I'd meet the SM and have his word the car wouldn't get driven by Jimmy, the 16 y.o. trainee, and it would be stored inside. He was cool, listened to me, and dealt with the problem professionally. Anything else is not befitting a $70K auto dealer IMHO. Good luck, keep us posted.

zeta08 · 05-10-2008, 07:00 AM

I was just checking my service invoice. I was a little upset they charged me to change my oil (I gave them the filter and oil - 8qts). Now I realize they charged me for a ninth qt of oil too! Level's fine, but 9 qts? What did they spill a qt? Yes, I will ask them. Damn steelers.