LSInnovations

iTrader: (7)

A squeezing sound that sounded to me like a belt tensioner or slipping belt started today on C6 Z06 LS7 motor.

The car has 15k miles on it. It started where I could barely hear it and after a few miles it got alot louder where its constant now, hot or cold.

I pulled the valve covers. Checked all the pushrods and they are all great. No broken valve springs that I can see and rockers all good/tight.

The sound isnt grinding or anything, its just like in the video. When revving the motor the sound is minimal and on deceleration it is loud.

When driving the car, it has no loss of power, runs great. Under throttle you cant hear the noise really, its loud when decelerating and idling

Here is a video of it idling and revving it up. The sound is pretty clear and just like in person.

VIDEO:
http://www.youtube.com/watch?v=aCwZkZKa8W0

davidws6

iTrader: (36)

Sounds to me like you have a dry rocker arm. Probably the bearing on the rocker shaft or push rod. The way it sounds it's gotta be in the valve train on the upper end, something dry?

John B

iTrader: (10)

It doesn't quite sound like a belt but there's a real easy way to find out! Just take the belt off and fire it up....won't hurt a thing! Just make sure to get both belts!

Bink

could it be a pcv valve chirping .... seems too irregular for a rocker-but that might be it if its worn enough (wobble)??

gen3performance

iTrader: (9)

I thought maybe pcv valve too, but what about the dry sump system. Not to get off subject, but how does the pcv system work with crankcase vacuum?

LSInnovations

iTrader: (7)

The noise sounds like its coming from between the middle to back of the head. So I'm pretty definite its not from the front/belt area.

PCV?? hmmm i took that line on and off the valve cover when I pulled the valve cover. No difference.

Dry rocker arm...hmmm...all the pushrods poured alot of fluid out when I took them out.

This is the first LS7 I have taken apart. Do they come with the big 3/8" pushrods stock? It has large 3/8" pushrods in it that are tapered on the ends to factory sized....

-Joseph-

iTrader: (12)

Those are stock, they are also ~7.800" length.

LSInnovations

iTrader: (7)

Well wouldnt a easy way to check if its lack of oiling to just pour some oil onto the rockers under that valve cover and then start it back up?

ae13291

iTrader: (8)

would the dealer cover this kind of defect?? is your warrenty still active

LSInnovations

iTrader: (7)

Not looking to have a voided warranty due to the camshaft install etc in relation...

vtanju

iTrader: (2)

sounds like an exhaust leak to me, the squeaking noise is probably the exhaust system making vacuum. hope this helps.

volkan

98Camarod

iTrader: (43)

Damnit, I have the same noise, I thought you might have figured out what it was. I'm going to replace the cam retainer plate and hopefully that fixes it. Its an oiling issue. Hows your oil pressure once you are warmed up?

flyin ryan

iTrader: (1)

You might try a piece of rubber hose about 3/8" diameter or a little smaller.
Put one end in your ear and listen with the other end around the headers, plugs , rockers etc and I'll bet you will pick it up and be able to identify where its comming from.

Good luck with it.

UnitZ28

it's just an exhaust leak.. it's gonna be ok

LSInnovations

iTrader: (7)

Unbolted rockers/removed pushrods/coilpacks/ etc from entire side. Ran the motor only running on the passenger side.

This eliminates the possibility of it being an exhaust leak or valve train related. (Because no air is flowing out the exhaust with the valve train removed)

Basically im starting to think lifters or something else...


but the car did put down 560rwhp on the dyno yesterday ...not down on power.

Haans249

iTrader: (24)

Woa....that sounds like a trashed lifter man. You need to take it back to where ever you got the new cam installed, and have them pull the heads and check the lifters. Get a new set, as I'll bet 50 bucks you're gonna need them. What cam do you have in there? (duration/lift wise)

Adrian

LSInnovations

iTrader: (7)

I'll be doing whatever work is necessary when the problem is discovered. The installer won't be involved with the problem. Lifters is my guess too now.

Cam is a 23x/23x...

flyin ryan

iTrader: (1)

If you unbolted the rockers and removed the push rods why would you be thinking lifters ? j/c
Ryan

LSInnovations

iTrader: (7)

Because the lifters are pushed up but still slightly contact the cam shaft while the motor is running. Its enough to for the wheel to be spinning on the lifter as the vibration of the motor etc isnt going to keep the lifters up in the sleeves.

The noise is about 75% less with all the valvetrain removed but is still audible. Which leads me to suspect lifters.

Haans249

iTrader: (24)

I wasn't implying that it was the installers fault, just thought it would be an easy way to get the job done if you trusted the installer. **** happens you know. Ryan made a valid point, with the lifters not having any load and still making the noise, but anything is possible. I would do what he suggested, and some rubber hose (small diameter) and see if you can get the exact pinpoint of where the noise is coming from. Another good tool is a long screwdriver, just put the handle to your ear and touch it in places you think the noise is coming from, thats a good way to pinpoint the area as well.

Keep us updated!
Adrian