johnC5

Engine Experts: What is this noise? The noise is coming from the engine, and can be heard a few feet from the car with the hood closed:
http://www.brightland.com/cf/video/Z06Noise.wmv (Large: 1.1MB) http://www.brightland.com/cf/video/Z06Noise_small.wmv (Small: 732KB)

rrobert22

Does it make that noise with the clutch in? Mine makes that noise but only with the clutch let out. If its not that then it could be piston slap, or valve train. Not sure on that one. Good luck :cheers:

johnC5

The car does make the normal drivetrain noises with clutch in/out. The noise in the video is a different noise.

Initially, the noise appeared to occur when the engine was cold, intermittantly. Now the noise has increased, and is most audible when the engine is hot.

nfshotrod

Main/rod knock

vettman10

It sounds like rocker arm noise to me. The pitch and frequency is wrong for a main/rod bearing. And If your oil pressure has not decreased from what it was before the noise, then it is definately not a bottom end problem. When a main or rod bearing goes, so does the oil pressure. If it is a loose rocker arm, it could have been caused by a bent push rod, some of the rocker arm needle bearings missing (a known problem on the LS! engines), or a loosened rocker arm retaining bolt. But at any rate, it needs to be looked into immediately.

Dave00C5

:iagree: Get down low to the ground by the front tire and see if its louder down their and more of a metallic knocking. Sounds to tinny to be a rod or main.

johnC5

So the sound is not normal? Last dealer visit, it was pronounced normal. However, since that last dealer visit, the sound is now always there (it was intermittant before the last dealer visit).

Oil pressure has not changed.


[Modified by johnC5, 6:41 PM 2/18/2003]

johnC5

Interestingly, with the hood open, it's harder to hear. With the hood closed and a few feet away, it's easy to hear (as well as in the car). When down low, by the front tire, it is indeed louder.

Z06 Quin

Is your car stock or have you added headers?....or anything else....

have you over revved it?


[Modified by Z06 Quin, 9:18 PM 2/18/2003]

0vetteshop

???
Engine Knock or Lifter Noise (Replace O-Ring) #02-06-01-038 - (12/02/2002)
Engine Knock or Lifter Noise (Replace O-Ring)
2001-2002 Chevrolet Camaro

2001-2003 Chevrolet Corvette

2001-2002 Pontiac Firebird

2002-2003 Cadillac Escalade, Escalade EXT

2000-2003 Chevrolet Suburban, Tahoe

2001-2003 Chevrolet Silverado

2002-2003 Chevrolet Avalanche

2000-2003 GMC Yukon, Yukon XL

2001-2003 GMC Sierra

with 4.8L, 5.3L, 5.7L or 6.0L V8 Engine (VINs V, T, Z, G, S, N, U -- RPOs LR4, LM7, L59, LS1, LS6, LQ9, LQ4)

Condition
Some customers may comment on an engine tick noise. The distinguishing characteristic of this condition is that it likely will have been present since new, and is typically noticed within the first 161-322 km (100-200 mi). The noise may often be diagnosed as a collapsed lifter. Additionally, the noise may be present at cold start and appear to diminish and then return as the engine warms to operating temperature. This noise is different from other noises that may begin to occur at 3219-4828 km (2000-3000 mi).

Cause
The O-ring seal between the oil pump screen and the oil pump may be cut, causing aeration of the oil.

Correction
Inspect the O-ring seal and replace as necessary. Use the applicable part number listed below. Refer to the Engine Mechanical sub-section of the appropriate Service Manual.

Parts Information
Part Number
Description
Qty

12557752
Seal-O/Pmp (O-ring)

(F and Y Cars)
1

12563963
Seal-O/Pmp (O-ring)

(C/K Trucks)
1

johnC5

Car is stock. I have never over-revved the car. However, the car now has about 70 dealer driven miles on it. I noticed the noise after the last dealer visit (where 23 miles were added). But, the noise has always been there since day one, it just recently got much louder, and now does it all the time.

johnC5

C-5 TECH,

That sound like a good lead. Question: why did the noise recently get louder?
The car has ~7000 miles on it. One change that was done recently after an oil change: a switch from a K&N performance Gold Filter to a UPF-44 (which seemed to increase oil pressure).

Thanks for the tech info. I really appreciate it. :cheers:

BONESTOCKC5

Does it drive fine, good power? any check engine light? what is the oil temp when the coolant is into regular operating temp?...............................thes e things make all types of racket due to the valve train i.e. roller lifters and rockers. :)

BONESTOCKC5

Just listened to your video.. i'd say this is a rockerarm noise. Too fast to be a bearing noise. You need your valve lash set. :yesnod:

rcws6

Question, his car is either a 2001 or a 2002. Why would you already need this done if the car only has 7k miles :confused: . Mine seems to do the same, but once it warms up I can't hear it over the torque tube noise when you let the clutch out. Anyway, just curious because your solution (valve lash), is not a minor fix.

johnC5

BONESTOCKC5,

Oil temp is around 217 when fully warmed up. When in traffic, driven harder, 223. No lights, no codes.

rcws6,

Car is a 2002. There may also be an oil use issue (I'm checking into it).
A ticking/knocking noise has been present since day one. Initially, it sounded like all the lifters, with just one lifter making noise, and went away when warmed up. Now a single ticking/knocking noise is present when warmed up and does not go away (as in the video).

johnC5

First, car does not seem to be using oil. Black material appears to be coming from the road.

Second, dealer heard the noise. I showed them the TSB. The service manager stated that he was aware of the TSB, and the GM rep stated that the O-ring change will not fix the problem.

Is it possible to get a GM engineer to view my video?

BONESTOCKC5

Valve lash is set at factory, To get the most power from an engine with hyd. lifters they set them at zero lash ( however most engine builders set em at .015 to .030 down) Any way, they set them that way and some times its just "loose" enough to make a noise. I'll betcha if you check em one or two are loose. Also setting lash is not a huge deal. I am an ASE cert. master tech and an ASE master engine machinist. :D

johnC5

I had a solid lifter car in the past. Is the adjustment similar for the LS6? Does it simply involve removing the valve covers to get at the necessary elements?

vettman10

Valve lash on a LS1/6 is not adjustable. It's a machined tollerence that does not need periodic adjustment. So, if you have a loose lifter/rocker arm, its due to some type of mechanical failure. The only way to adjust the lash on this engine is with different length push rods or with shims. It should only need adjustment if the heads were machined or a small base circle cam was installed. If the noise is changing, then this is cause for concern - try a different dealer.