i am not sure what else it can be, well it's been about 7 mos since the (miss down shift) and ever since then i cant get rid of this valve train nosie,

7 mos ago

the chevy dealer had in installed 2 new push rods to replace the ones that had bent, (dirvers side)

1 month and 500 miles later of normal driveing,

2 more push rods to replace bent ones (passenger side)


and now not more then 1000 miles since the last 2 push rods
the sound is still here on a scale of 1 to 10 it's a (2-3) not real bad but i know not good.

so i said the hell with it and me and a buddy took off my valve covers
to see that nothing was wrong all the push rods are good, rockers are fine, rocker stand's, and of course they where all tight....?

so why do i still have the nosie could it be a bent valve, bad cam Lob'

all stock valve train 17000 miles on car 00 frc...

:confused:


thank's


[Modified by torched you, 7:46 PM 2/24/2004]

 

Spin the engine over with the rockers installed, and see if all of the rockers seem to move the same amount. It should be fairly obvious if you have a flat love or broken lifter. Also, if a valve is bent, it probably won't seat all the way, and should leave some "slack" in the pushrod-rocker-lifter when off of the cam lobe.

Also, if you haven't, I would pull all of the pushrods, and "roll" them on a piece of glass to make sure they are perfectly straight. They could look straight installed, but actually be slightly bent.

 

any one?

 

David is right - pop the push rods out of there and roll them on the glass if that is what you suspect

 

ttt

 

i shoud have been more clear in my post, i removed all the rocker arm's and push rods and the rocker stand's and checked them, everything checked out good :confused:

i just cant put my finger on it i know there is some gap somewhere in the valve train but where, ?

is there a tool that i can use to check the valve travel, cuase i did spin the engine with the valve covers off and everything seem'ed ok

thank's

 

Are you 100% positive it is a valve train noise? As you know noises resonate very well through the block. Have you given it a leak down test (bad seal) or compression test (ring issue). Do you have a stethascope, that may help really pin point the noise. Other thoughts are a spun or hammered bearing, an oil pump shaft problem. How far did it over rev? Could you be getting timing chain slap from a streched chain?

The next easy thing to do is take the serp belt off and run the car for a few minutes, just to eliminate the accessories as a problem (not too long, do not want to over heat it).


[Modified by Ragtop_Rob, 7:05 AM 2/26/2004]

 

Could it be a collapsed lifter? they can be hard to find. :rolleyes:

 

are you getting any misfire codes?

 

Hmm. Dad and I have both missed shifts in his car and we haven't heard any of these noises coming from it. You must have really revved the crap out of the engine.

 

[QUOTE]Are you 100% positive it is a valve train noise

well i,am 99.9 % sure its comeing from under the drivers side valve cover when you frist start the car it's engine sounds great after about 5-10 min. idleing then you start hearing it and it even does it under a load so that tells me it's not a bareing.

now back to the miss (up/down shift) i was going in to 4th from 3rd@109mph, mind you and i pulled 2nd gear the rev limiter dont do s@#* when you pull the wrong gear.

and you m6 guy's you only get about 77-78mph max in 2nd @6100rpm with stock gear so i whent about 31mph over in 2nd gear what that comes out to in rpm i dont know but i know it's high

and if you seen the push rods that came out that head it's a wonder that the car still ran.

and there are no type of code's comeing up at all,

im gonna order some LPE rocker arm stand's (billet steel) not cast alum like the stockers . and some new stock rocker arm's and a good set of after market push rods and see what she sound's like after that i'am hopeing its not a lifter i sure dont wanna take my head off lol.

thanks everyone for your comment's ps will post after new part's

 

Compression test - If you've got a bent valve it won't seat properly, so a comparison with other compression in surrounding cylinders should give it away

 

Definitely do a compression test. I missed a shift late this summer and it just wasn't running smooth. I could feel the miss. I first pulled the plugs and the #7 plug was black. Did a compression test and had 210-215psi on all cylinders except #7 which had 105psi. Pulled the head and both valves were bent.

(side note) This was with my previous set of 5.3L Absolute Speed Stage-2 heads and the G5X2 cam, NOT my new set of Patriots. I was running a pretty close PTV clearance and just floated the valves on that cylinder.


[Modified by MTWallet, 11:47 PM 2/27/2004]