Please help diagnose this noise
Please help diagnose this noise Background: 1997 C5 Corvette, recently installed a new OEM GM LS2 shortblock with my (used)TSP ported 243's with 30k mi on them, new Torquer V2, new pushrods, new LS7 lifters, new PAC 1518 springs+retainers, new oil pump, timing chain, etc.
Started with dino oil, 200mi, changed and added 10w40 Mobil 1, ran for ~500-600mi, changed to Pennsoil 10w30 synthetic at ~800mi and motor developed this knock around 200mi later. Oil pressure is around 45psi cold both before and after the knocking developed (no change).
Engine has been street tuned with wideband, afr is around 13:1 at high rpm with no knock detected (conservative tuning).
http://www.youtube.com/watch?v=g_J1q6oj5yM
Started with dino oil, 200mi, changed and added 10w40 Mobil 1, ran for ~500-600mi, changed to Pennsoil 10w30 synthetic at ~800mi and motor developed this knock around 200mi later. Oil pressure is around 45psi cold both before and after the knocking developed (no change).
Engine has been street tuned with wideband, afr is around 13:1 at high rpm with no knock detected (conservative tuning).
http://www.youtube.com/watch?v=g_J1q6oj5yM
Last edited by Billdog350; Aug 25, 2010 at 09:49 AM.
This cam bolt deal is suspicious. How did the cam bolts back out? Under torqued? The cam gear keeps the cam's axial alignment. That allowed the cam to walk backward. Did the lifters get hurt when it did that? Did you inspect the lifters when that happened? My guess is a bad lifter with what we have here so far..
Last edited by frito1; Aug 23, 2010 at 06:40 PM.
I do happen to have a brand new set of GM LS7 lifters I can install if that ends up being the issue (of course cam might be toast too).
This vid was taken about 20 min ago. I've taken the valve covers off and everything is tight (collapsed lifter not likely). As everyone knows I need to yank heads to find out if this is lifter related so I have a while to go before I get there. I'll update this thread once I know for sure what's wrong, however I'm hoping someone might know that noise right off the bat. I do have a magnetic drain plug so as soon as I drain the oil I'll have an idea of what might be wrong (needles from the lifter bearings, chunks of ____, etc).
I'm REALLY hoping for a lifter rather than crank/rod bearing. Sure I'll need a new cam or a regrind, but at least I don't need to yank the motor. I'm NOT happy about the possibility of having to yank that motor again.
This vid was taken about 20 min ago. I've taken the valve covers off and everything is tight (collapsed lifter not likely). As everyone knows I need to yank heads to find out if this is lifter related so I have a while to go before I get there. I'll update this thread once I know for sure what's wrong, however I'm hoping someone might know that noise right off the bat. I do have a magnetic drain plug so as soon as I drain the oil I'll have an idea of what might be wrong (needles from the lifter bearings, chunks of ____, etc).
I'm REALLY hoping for a lifter rather than crank/rod bearing. Sure I'll need a new cam or a regrind, but at least I don't need to yank the motor. I'm NOT happy about the possibility of having to yank that motor again.
Last edited by Billdog350; Aug 25, 2010 at 09:51 AM.
Have you checked your oil for shavings or anything like that? A spun bearing will leave gold metal flakes in the oil and usually you hear a squeeking noise. I am having a hard time pinpointing what that noise could be. It would be the loudest lifter tick I have ever heard if that is what ends up being the problem.
Well, its torn down to the bare block. Oil filter was actually clean, the magnetic oil plug did have some debris on it.
Second lobe from the front of the block (#2 cylinder) is toast due to the lifter completely crapping out. Its flat on one side with big chunks completely blown out of it.
John, I'll be calling you guys tomorrow to help figure out the best plan of action going forward. I obviously need a new cam, I have new GM lifters but I'm not sure those are the way to go.
All the parts I have on this build are sourced from Texas Speed and they have been good to me so we'll see if we can get this one nailed for good!
Thanks to everyone for the suggestions!
Second lobe from the front of the block (#2 cylinder) is toast due to the lifter completely crapping out. Its flat on one side with big chunks completely blown out of it.
John, I'll be calling you guys tomorrow to help figure out the best plan of action going forward. I obviously need a new cam, I have new GM lifters but I'm not sure those are the way to go.
All the parts I have on this build are sourced from Texas Speed and they have been good to me so we'll see if we can get this one nailed for good!
Thanks to everyone for the suggestions!
