grinder11

iTrader: (1)

I have an LS7 installed in a 2000 C5. After a 1,000 mile "break-in, I have run it through the gears 3 or 4 times, and it "WAS" running great. Due to the tuner not properly setting the rev limiter, when I missed a gear with the pedal on the floor, the motor probably hit 7800 RPM, minimum. Ever since, there has been an intermittent "clicking" somewhere inside the engine that I'm unable to pinpoint, even with a stethoscope. Since I was 150 miles from home when this happened, and all gauges were reading normal, I gently drove the 150 miles home. When in the garage at home, I pulled the valve covers to look for broken springs. They looked O.K., but I did bend the pushrods slightly, so I got a new set of the same length. Checked compression, and 6 cylinders showed 200lbs., 2 others showed 190-195lbs.. I had installed a magnetic drain plug several years back, so I changed the oil to see if there were any metal shavings/debris on the plug. Nothing. I've put over 600 miles on it since then, and the noise is no worse. Oil pressure is very good. I have noticed that it seems that it is loudest around 2,000 RPM, but hardly detectable at idle. I've read the LS7 valve train posts on the "other" forum, but they seem to be kinda stumped as to what is causing that issue. Now, I'm stumped as to what's causing my issue, too. PLEASE-HELP!!!!

SHovV

iTrader: (1)

I'm betting you messed up a lifter.

grinder11

iTrader: (1)

What do you mean by "messed up "? I have nothing but oil on the oil pan's magnetic drain plug. I am just curious what makes you think this. Not dis-agreeing, just sayin'...

DietCoke

iTrader: (18)

Check all the springs?

grinder11

iTrader: (1)

Yes. Well, I haven't removed them-YET! But, after a pretty close visual inspection, while still on the heads, they all look O.K.. Years ago, I experienced a broken valvespring, and it was much louder, and not as intermittent as this noise is. However, I'm not saying that it's impossible. It could've happened again. I did replace the pushrods, which were bent, so I know the valves floated. It screamed pretty good, I'll tell ya. I'm running stock LS7 hydraulic lifters, with stock anti-rotate plastic lifter trays. Several people have mentioned I could have a messed up lifter. I guess I don't know what they mean by messed up. Maybe like a frozen wheel? But wouldn't this make for debris on the magnetic drain plug? As I mentioned before, I have no debris, like steel shavings, broken pieces, or anything else on the magnetic oil drain plug. It is VERY frustrating, and perplexing!!!

one fast zo6

iTrader: (490)

Time to pull the heads! I just destroyed a engine this way. It tore the lifter wheel right off the lifter! Also check valve retainer to valve seal to see if they
hit.

SHovV

iTrader: (1)

What I mean by a messed up lifter is perhaps the internals of the lifter got jammed or ruined during the over rev causing slack and not allowing it to pump up and receive oil pressure correctly, which in turn allows it to just bounce up and down along with the pushrod which would create the tapping noise you're hearing.

Try this. Push down on all the rocker on the pushrod side or take the rockers off and push down on the pushrods, you shouldn't be able move them.

I had a lifter go out on myS7 during a rebuild and I could push the plunger in the lifter down with the pushrod.

I hope I explained that correctly

Millenium Z06

What lifters? How fast is the tick, is it twice the crank speed or crank speed?

grinder11

iTrader: (1)

You did. Thanks to all who have offered help/advice. I'll pull the heads soon and post my findings.

grinder11

iTrader: (1)

Still, if a lifter or something has let go inside the motor, I can't figure out why there's no debris on the magnetic drain plug.