UPDATE (Feb '18) For anybody else trying to diagnose their problem on the forum like I was, heres another point of reference. I was exactly right with my assessment. The lifter did spun in the tray.
Pics: https://ibb.co/dOHfsn https://ibb.co/haPRXn

UPDATE (01/28/18): After cleaning throttle body and filter, I went for a drive monitoring it. It was still a little off but again at full temp (200+) it loped just fine. Parked it for a hour. Got back in it, when I started it (oil 137 degrees) it wasn't loping at all. At a red light it started a light squeak. I figured it was a belt or pulley. Over the course of 5 minutes the squeak got worse to the point where i pulled over. As luck would have it, squeak sounds like its coming from inside the engine. the squeak would kind of stop for a little on its own, put when i barely hit the gas and made it shake it would come back and stay for a little idling. I did this to try to find the source. Definitely sounds internal. It was getting worse. So i limped it back home (under 1.5k rpm the whole time) and it started clicking and all sorts of sounds, and rpm fluctuations were happening, and it would drop below normal idle almost trying to die. Power did seem fine though. Oil pressure was above 30 psi minimum at all times.

So, with this in mind... would it be fair to think its a failed lifter? Maybe it failed and is scoring the camshaft? I know to replace them is a big job. I don't have the place or tools to do so. My plan right now is to first pull the valve covers and look in there (honestly I'd just look for broken things, not really sure what to check) Then the pulleys (doubtful its them). I read somewhere that you can see the cam lobes when the intake manifold is off? If so, that would be my third step. If all is well I'd stop there and buy all the parts for the lifters replacement. Would draining the oil and letting it sit without oil hurt it? Should i keep it in there to move it onto a trailer on its own power? and also, would a compression test help or hurt it as it probably would score it even more. As always, Thanks all for the commends and help. I'm very appreciative of anything you guys help with me.


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Hi all, it regrets me to make this post but i'm worried about my pride and joy. I've owned my C5 Z06 for a few years now and it's never given me any issues. (well if breaking other peoples neck is one well then..) However, I guess i knocked on wood too hard and something came up. I drive it 4-5 times a month, and check oil 1-2 times a month. All other engine bay fluids are good. Car has H/C/E. <65k miles. I D/C my battery most of the time when I park it because it will die after a week of not driving it. Okay here it goes:

Went to start the car one day after not driving for 4 days with the battery still connected. Got a low oil level DIC message with no code. Immediately turned off and checked oil. Was sort of all over the place on the stick every time i cleaned and pulled it out. Definitely some in between the dots though. (nose of the car was slightly downhill) Got in and got no codes this time. Assuming the battery was almost dead and throwing warnings, tried to turn it over.. and what did i know battery was too low.. almost enough to turn over but didn't on the first attempt. Got my jumper pack and hooked it up. Still no messages/ codes and cranked easily. Temperature was 33-42 so a cold start. Idle is always erratic on a cold start like that but once it started warming up (oil 60-70F) the lope it normally starts to acquire was different. The car has no cats or mufflers, so it is very loud. You can hear every subtle noise. After having it sound the same for years I definitely noticed a difference. Instead of the normal lope pause lope pause.. it would lope then make more noise and try to lope again without the pause, if that makes sense. Let oil warm up to 150F+, still sounded different. Oil pressure and all other gauges were fine. Turned off to do research. Well, as the internet goes, i found that it can be a little of everything.

Next day. Temp was 33-40F. I came out and looked for leaking fluids, nothing. Checked oil, It was barely above the minimum hole but a solid indication this time. Added a quart of Mobil 1 5-30 full syn (whats in it now, oil change is ~2k miles old..). Oils at full now. I then checked for vacuum leaks by just running my hand over easy to reach rubber hoses and looking for holes. No dice. Took the red plastic covers off looking for anything... nothing abnormal. Got in, No codes or messages.. Started just fine. Same cold idle (normal) but again.... just like yesterday.. the warming idle was different. I checked hoses again with it on and couldn't find anything. Let it warm to 140F+ and went for a short drive. Drives perfectly normal, still sounds like a beast. Still idled slightly different. I did a little higher rpm driving trying to hear noises or anything and after that the idle returned to normal! (oil 200F+ now). I may have heard three unaligned metal noises about 3/4 seconds apart from the hood around 3k rpm light load. Also think i'm paranoid at this point. Took videos at this point, cold start, warming, and warm. Listened for noises based of what ive read online. My motor has always been very noisy and over the exhaust as well i cant hear anything. Lots of clicking (i assume injectors) and just so many noises its a senor overload to me. Put it to rest and read more.

And then there's today. Started fine, looked fine, same cold and the (different) warming idle as before. Went for a 5~ mile drive. At this point im very paranoid from reading and swear i hear atleast 15 new noises and things that maybe possibly didnt exist just a week ago. Drives and accelerates (1/2 throttle max to 60 mph) just fine. Still sounds amazing under acceleration. (longtubes, catless X pipe, no muffs). Parked at my destination and stayed for a hour or so. When i returned to the car, oil was 146F and the idle was the same different one. Backed up to see if i leaked anything, and nothing. Drove the car slightly harder on the way back, oil now at 200F+ and it idles normal like a champ again.

I just don't know. Ive read failing lifters causing a click, and hear videos of that but mine makes so much noise i wouldnt know if mine had that sound or not! Those are also higher mileage. One guy had a leaky exhaust manifold gasket. One guy had a loose spark plug. Below are videos of it doing the warming idle the 2nd day, reving to 3k the 2nd day, and a under the wheel-well one today. As i said its always made a ton of noise for years and i read all modified LS's especially with upgraded valvetrain and cam will be noisy so i never really paid attention to all the little engine noises to notice whats different down there. I just know the idle is slightly off.

Warming Idle:


Revving:


Under the wheel-well


Any help would be appreciated. Thank you

 

a better way to check for vacuum leaks, with the engine running spray some carb cleaner around the intake manifold or anywhere there could be an air leak and listen for any changes in idle... also get a long screwdriver and put the handle up to your ear while holding the other end against stuff like the valve covers, injectors, pulleys (make sure to get the tip on a non-rotating surface obviously), etc, basically anything you suspect that could be making noise... the screwdriver will transmit the noise to the handle and it will make thinks pretty easy to pinpoint... on my old trans am the evap solenoid was clicking and sounded similar to yours but it could be lots of things

 

Of course the vids are NOT the best way to diagnose your issues, but it all sounds rather normal to me considering what you have.

I would rely on the codes and go from there. Above all, I would drive it for a while before I started throwing parts at it.

But......I will tell you this:

From great experience I will ASSURE you that these machines will do crazy stuff when the battery voltage is not sufficient.

Enough said !

 

Moved to C5 Tech.

 

Good idea about the carb cleaner. I knew about the screwdriver trick but im hesitant about putting metal against it. I suppose i'll give that a try today. As for codes, It never threw a CEL.

 

Also, check your battery, without anything on it should read 12.5V or more. Once it goes below that voltage, you will begin to find all sorts of gremlins jumping out. When it is below 12.5V it is time to replace it. When it is cold it will show a little less voltage than normal. When you are going on a drive, wait til the oil temp reaches 200+ then pull over and turn the engine off. Let it set a minute and re-start. It would be you are hearing differences in metal expansion on a cold engine vs warm or summer temps. Personally I do not like to start my car under 45 degrees because I always hear strange noises under the hood--lifters, solenoids, etc.

 

Update bump

 

anybody?

 

have you checked anything else since then??

 

Not since the update, I'm going to follow the rough outline I mentioned. To start, valve covers are coming off today hopefully.

 

Go to or internet, Harbor Freight....a mechanics stethoscope $3.99

Even I can afford that.

 

First, did you check the battery voltage? did you use a scanner or the DIC to check for DTC cades. If you are hearing real engine sounds, it could be engine knock and that would give you a DTC. Have you looked under the car at the drive line, if you have an oil leak you will see either some oil droplets or dark coloring on the trans or rear end. Also, most LS1 engines will have lifter noises until the oil has heaated to about 180-200 deg.