Need Help diagnosing a knock. Vid inside.
Need Help diagnosing a knock. Vid inside. So after the drive to CA from NM, my engine has slowly developed this knock. When the motor was first started up, it had really loud valvetrain noise. Sounded like a sewing machine. But I read up on it and apparently that is common when running a big cam in an LS engine. So I thought nothing of it. Now when I arrived to CA, the car was running fantastic but the valvetrain noise seemed to be getting louder. And then the sound changed a bit from sewing machine to a steady knocking consistent with RPMs. I immediately thought "pushrods" because I am running a 7.325 length pushrod to accomodate for the LS7 lifters being taller, and my milled heads being shorter. So I grabbed a set of stock length rods off a guy on here for free, installed them and nothing changed. I have triple checked all the rocker arms for damage and torqued them down to 22 ftlbs. I don't *think* that this is a rod knock and I am starting to lean towards collapsed lifters. Since I had so much bad luck with the TSP LS7 lifters from the getgo that is my next thing to try but ffffuuuuuuuu I dont wanna pull the heads!!! Have a listen and tell me what you think..... Oh BTW everything in the motor has about 1000 miles on it.
http://www.youtube.com/watch?v=NQNW94OUFTc
http://www.youtube.com/watch?v=NQNW94OUFTc
Last edited by 89L98T56; Aug 15, 2010 at 10:06 PM.
Use a mechanics stethescope and pinpoint where the noise is comming from. Listen to it from underneath the car also to rule out bottom end problems. Oil pressure good or I assume you would have posted this....?? Unless some trash got in your lifters I can't imagine them giving up with so few miles. Doesn't sound exhaust leak related at all but I would check all your plug wires to make sure they are snapped on correctly. See if any pending codes are present and that might give you a clue....
Keep us posted.. Has me stumped but it is very hard to diagnose this stuff from an internet video....
One last ??? You mention a large cam so what are the cam specs, heads milled and HG gasket thickness? Was the PTV clearance checked....
Keep us posted.. Has me stumped but it is very hard to diagnose this stuff from an internet video....
One last ??? You mention a large cam so what are the cam specs, heads milled and HG gasket thickness? Was the PTV clearance checked....
Sounds to me like its coming from the top end. But seriously for starters how about removing the valve covers and making an inspection. If you fear its a bearing unplug each plug wire one by one and start the car. If it's a bearing the knocking will go away on the cylinder you unplugged due to no pressure on the bearing
Use a mechanics stethescope and pinpoint where the noise is comming from. Listen to it from underneath the car also to rule out bottom end problems. Oil pressure good or I assume you would have posted this....?? Unless some trash got in your lifters I can't imagine them giving up with so few miles. Doesn't sound exhaust leak related at all but I would check all your plug wires to make sure they are snapped on correctly. See if any pending codes are present and that might give you a clue....
Keep us posted.. Has me stumped but it is very hard to diagnose this stuff from an internet video....
One last ??? You mention a large cam so what are the cam specs, heads milled and HG gasket thickness? Was the PTV clearance checked....
Keep us posted.. Has me stumped but it is very hard to diagnose this stuff from an internet video....
One last ??? You mention a large cam so what are the cam specs, heads milled and HG gasket thickness? Was the PTV clearance checked....
Sounds to me like its coming from the top end. But seriously for starters how about removing the valve covers and making an inspection. If you fear its a bearing unplug each plug wire one by one and start the car. If it's a bearing the knocking will go away on the cylinder you unplugged due to no pressure on the bearing
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Launching!
Joined: Sep 2008
Posts: 234
Likes: 0
From: Ashland,VA
I hate to say it but sounds kinda like bottom end to me. If it were valvetrain related it would be half RPM speed. sounds like it is same as RPM speed at idle. Just my opinion. disconnect fuel injectors one by one and see which one changes it. I hope im wrong buddy really i do....
I hate to say it but sounds kinda like bottom end to me. If it were valvetrain related it would be half RPM speed. sounds like it is same as RPM speed at idle. Just my opinion. disconnect fuel injectors one by one and see which one changes it. I hope im wrong buddy really i do....
Launching!
Joined: Sep 2008
Posts: 234
Likes: 0
From: Ashland,VA
Remember, engine noises are generally synchronized to either engine speed (crankshaft, flywheel, connecting rods, balancer, or pistons and related components) or one-half engine speed (valve train noise such as rocker arms, valve lifters, and timing chain). Try to determine the rate at which the noise is occurring.
That is straight from GM Service Information for a 2000 Camaro LS1. Not trying to say your wrong or anything but just dont discount that it could be bottom end noise.....again i hope im wrong i would hate for that to happen.
Staging Lane
Joined: Aug 2009
Posts: 53
Likes: 0
From: Edmonton Alberta , Canada
Atleast from what i can tell in the video, the intake manifold is amplifying the sound, which if it were me, id start looking around up top. one would think if it were a rod bearing spun, or the like there would be some indicator , like lower than usual oil pressure etc.
Pull your valve covers and inspect each rocker arm. They should rotate FREELY on the bearings. There should be NO friction/tension.
I had 3 rocker arms fail on me and it made a similar noise
I had 3 rocker arms fail on me and it made a similar noise
Sounds like my car after it broke a small piece off the #7 ring land, but I see you have forged pistons.
It would be nice if you could take a look inside the bores without taking it apart. Good luck and let us know what you find.
It would be nice if you could take a look inside the bores without taking it apart. Good luck and let us know what you find.
UPDATE
Posted new vid...
I pulled the motor out this weekend and I have yet to find anything besides this....
About half of the lifters I am able to compress by hand with a pushrod. The other 8 are hard as rocks and wont move. I also pulled the bottom end apart and all the bearings look perfect. I only pulled the #8 piston out to inspect and it looks fine besides a little scoring on the friction coating on the skirt. cylinders look great, can still see the cross hatch pattern. No foreign objects anywhere, nothing broken. But 2 of the lifters have hairline cracks on the bottom next to the rollers. These came out of the drivers side.
Another question....all of my rocker arms make a crunching sound when moving the fulcrum up and down. Is that normal?? Will post pics of everything soon. Still haven't really found the source though unless those lifters are shot.
Posted new vid...
I pulled the motor out this weekend and I have yet to find anything besides this....
About half of the lifters I am able to compress by hand with a pushrod. The other 8 are hard as rocks and wont move. I also pulled the bottom end apart and all the bearings look perfect. I only pulled the #8 piston out to inspect and it looks fine besides a little scoring on the friction coating on the skirt. cylinders look great, can still see the cross hatch pattern. No foreign objects anywhere, nothing broken. But 2 of the lifters have hairline cracks on the bottom next to the rollers. These came out of the drivers side.
Another question....all of my rocker arms make a crunching sound when moving the fulcrum up and down. Is that normal?? Will post pics of everything soon. Still haven't really found the source though unless those lifters are shot.
