Pekka_Perkeles

Damn,

Last autumn I got a P0343 code in my Vortech-supercharged Z06. Cam bolts were loose, but luckily nothing was broken and two weeks ago I was able to fix the problem with new ARP bolts & loctite. After getting everything back into the engine bay, I started the engine and it ran at idle for something like 30 minutes or so. Everything seemed to be perfect, normal water temperature, normal oil temperature, no problems with belts. And the car idled just perfectly. And no P0343 code anymore.

After 30 minutes of idling I finally increased revs to something like 2000 rpm. Suddenly there was loud clicking noise. I mean, VERY loud. I quickly shut down the engine. First I thought that maybe belt was broken. But the noise didn't come from the belt or accessories, but instead from the right side / inside of the engine. I started the engine again, but the clicking noise was so loud, I didn't have nerves to let it run. Last weekend I started the engine again, and the noise was still there. And now I noticed the P0300 code. After browsing Corvetteforum a bit, I noticed that it's possible to have mechanical reason for P0300. I visually checked valve springs, and they seemed to be in good condition. I also removed rocker arms and tried to push pushrods to see if some of the lifters would feel "soft". It wasn't perhaps the correct way to check lifters, but I didn't know any other way either. Anyway, after putting everything back and started the engine, clicking noise was much lower, i.e. something like this:

http://www.youtube.com/watch?v=TJYX2OfTRQY

What do you guys think? Is it possible that lifter breaks without any particular reason like revving hard? Note that the car had been stored for 6 months in cold climate, so perhaps that had also something to do with possible lifter problem, but I don't understand how it broke only after the engine reached normal operating temperature.

When the car is idling, it's easy to feel exhaust pulses when I put my hand to the left side exhaust pipes, but in the right side (where noise is), those pulses do not exist or at least are very weak. The car does idle pretty well, but it's easy to hear that it's not normal idle, i.e. just like not all cylinders are firing. When driving the car, there's plenty of power, but of course as it's supercharged, it's difficult to say if there's bit less punch now. Anyway, Check engine -light is flashing, so there's unburned gasoline in the cats.

I measured plug wires (they were all around 750 ohms range) and also switched coil packs, but no effect, the problem - and noise of course - stays at the right side of the engine (i.e. not the drivers side but the other side of the car). Somehow I suspect lifter, not bent pushrod, because as I said, the problem started without revving too hard. And valve springs seemed to be fine. Also the car was running perfectly 30 minutes beforehand at idle. Of course as the engine is stock, who knows, perhaps piston is starting to break… I also visually checked spark plugs, and they all seemed to be fine.

Any comments would be appreciated.

Pekka

SteveDoten

PR's, roll them on a flat steel bench, you'll see a bad one
valvesprings, did you upgrade to comp 918's?
rockers, oe rockers torqued to spec?

if that is not the A&A kit, hat's off to the work involved to get to the cam bolts

Pekka_Perkeles

Valvesprings are stock LS6 springs. I also have stock rockers, that were and are torqued according to specs.

I'm going to check lifters using these instructions:

Pekka_Perkeles

Well, if anyone is interested - it was broken, or actually destroyed lifter. Here's couple of pics...

At this stage everything looks good...:



Still looks good, except that this particular lifter doesn't move at all...:



Now look what I found from here...:



Yep...it's a pin...



Here's comparison of another lifter and the pin...Now I know why one of the lifters won't move...



...it's because that pin is from the lifter that isn't anymore "roller" lifter...





Any comments how can I remove it from the block? And do oversize lifters exit? Or how to fix it?

One Nut

I vaguely remember a lifter removal tool looked like a slide hammer with teeth that fit inside the lifter and gripped on the lip where the retainer spring is then just pop the slideing part and it yanked the lifter out. I dont even want to think about what to do to fix the block if that did not survive the carnage. Were those stock roller lifters? during the read I was thinking to my self collapsed lifter I guess it was much worse if your lucky maby its just well I hate to use these words wedged..SORRY good luck

Pekka_Perkeles

Well, actually the problem I had was that I didn't notice the missing pin...



Here's the rest of the story (I didn't start the thread, but I finally realized what was the problem):

http://forums.corvetteforum.com/show....php?t=1733447