Noise with stethoscope while reving engine??

[truckins10]

Hey guy,
I had some KR that I thought I cured by turning the FP up, but one day Ill have alittle knock and the next alot. So I put a stethoscope to the block. I also get 2-4 KR at idle just reving the motor. It does it at about 2700-3100RPM and I can hear a chattering/slight tapping noise from my stethoscope if I put it on the block by the knock sensor. Anybody have any ideas what it might be??? Poss rod bearing, valve train??? Its definitly triggering false knock. If anyone has experienced something simulair to this I'd like some feedback. Thanks Fern Sy#477

 

[Maverick87]

check the converter bolts.

 

[Falco]

Something rubbing around. Do you have a stock setup? Check the downpipe isn't near to something, frame, tranny house. Check the converter cover bolts, and the converter's bolts too. Beside this if it comes from the back of the engine it could be something noisy in the valvetrain for example. Do you get the same noise when the engine is cold? If neither of the above, it's reported that the tranny (tc) can produce a noise, which the knock sensor could pick up.

Later,

 

[truckins10]

Falco, I found today that it is definitly coming from the passenger side rocker cover. And the scantool registers about 10KR when its making that noise. Ive probably been chasing a false KR problem the whole time. Whats my next step now??? Adjust the valves, see If I notice any broken valve springs or worn valve guides???? Thanks for the replys guys. Fern Sy#477

 

[Falco]

Yep. Pick up the valve cover, check it for loose rocker arms. You can also check for bad lifters, by pushing down the pushrods. Someone mentioned this method a while ago here. If no broken parts found, readjusting the valves could be an idea...

Later,

 

[truckins10]

UPDATE,
Took off the valve covers and dissasembled evry rocker on the pass side. Checked the rocker stud high,all good, checked the rockers and springs, all good. Then roled each pushrod on a flat surface, and sure enogh found one with a noticable bend while the others were perfect. Going to order one from GM tomarrow and try it. Those pushrods are dam close to the heads. N-E-ways, keep you guys updated. Thanks Fern Sy#477

 

[lSyclonel]

if that does not fix it. wich i hope it does.Check oil pressure with it knocks like that, is if it goes down. i had that problem.