Knocking/Ticking at low RPMs
This is a discussion on Knocking/Ticking at low RPMs within the General Help forums, part of the LSx Technical Help Section category; I am hearing a knocking/ticking sound that relates to RPM that is in the top side of the engine, sounds ...
05-31-2012, 06:46 AM #1
Knocking/Ticking at low RPMs (Vids included!)
I am hearing a knocking/ticking sound that relates to RPM that is in the top side of the engine, sounds like it is coming from very high up in the engine, halfway or towards the back of the intake almost. although it could just be resonating something from a head?
Weirdest part is that I do NOT hear it at idle and not at all at initial cold startup. I hear it after I rev up a little and then just let the throttle out after it has starting warming up. I only hear it on the decel in lower RPMs as well, but Its possible i only hear it at the lower rpms as the car is so loud, hard to tell on that part.
I already double checked all wires/connections/header bolts I could get to and all good there.
Took this video on cold startup, no noise at all.
P1010307.mp4 video by bryceslu - Photobucket
Then this video starts with the car halfway to OP temp.
P1010308.mp4 video by bryceslu - Photobucket
Again you can hear it when I let off the throttle as the RPMs are coming down.
The noise seems most audible around the 20-30 second range, probably have to turn up ur volume as there is a lot of ambient noise.
Again the weird part is the sound is not there at all at cold startup, even when revving. Also not at all at idle no matter what temp. And then seems to go away again at full OP temp, or it at least quiets down to where its basically inaudible.
Last edited by bryceslu; 05-31-2012 at 11:30 AM.
05-31-2012, 04:03 PM #2
I'm not sure what you have going on man, its something i would need to hear in person.. It does sound a little like what mine was doing. I ended up crushing a lifter and bending a push rod..
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Did you over rev it at all? How hard are you on the car, I know mine gets worked hard most of the time.
05-31-2012, 04:53 PM #3
You crushed a lifter and bent a rod...after it starting making noise? or thats what it was?
Its a street car for sure...but I get pretty high in the RPMs every so often having some fun. hey thats what these cars are for!
05-31-2012, 05:13 PM #4
Are you a manual or auto? If manual and you missed a shift or hit a high rev, you may have bent a pushrod or two. Fairly easy fix, and I'd recommend getting some hardened replacements.02 Z28/LS1 NBM - TIN CAN RACING
Full bolt on, weight reduction mods, dyno tuned by FROST = 330hp/342tq New PB = 12.74 @109
05-31-2012, 05:22 PM #5
How easy is it to pull out the rods? The reason Im leaning away from rod knock is its very high up in the engine and I would think the noise would be present at idle and when its running cold. Meaning I can rev it up even when its cold and there is 0 noise. I dont know. really odd
But if its easy enough to pull rods I could try that.
Anybody have a lifter issue? what did it sound like?
On a side note...could it be from switching oil? I always use PP but they didnt have that so I got P Ultra instead...I did change oil about 300 miles or so ago...cant say it started directly after but oviously fairly shortly.
Last edited by bryceslu; 05-31-2012 at 05:37 PM.
05-31-2012, 06:20 PM #6
Rods are not hard, pull coils off valve cover, remove valve cover which is four bolts each side, you will see the rockers, loosen rocker bolts then unscrew by hand and leave them in the rockers, pull the entire rockers with the bottom tray to keep everything lined up and place them on some clean cardboard or something so they don't fall apart and get mixed up, pull the rods out and replace with new ones, lube rod tips with grease, when you replace the rockers you will need a torque wrench and torque them to 22 foot lbs, now the haines manual says to rotate your crank to set the piston position before you torque the rockers down, but I have never done that and have always been good on mine, what I have always done is after I have torqued them all down the first time is pull the fuel pump fuse and crank the engine over a few times then go back and check each bolt again for proper torque and alignment on the springs, once it's all set right, then you can replace the valve cover, coils, oh and that fuel pump fuse.
Sounds short and sweet, but just take your time and make sure everything is back the way you found it. Also do some research on the install process and look at pictures of pushrod install just so you have an idea what your looking at before hand.
Last edited by tdevil55; 05-31-2012 at 08:04 PM.
06-03-2012, 10:44 AM #7
Agreed, rods are real easy to do. Also I crushed the lifter and bent a rod by missing a gear. (rev limiter was disabled)
I didn't have the noise before the over rev, and I only heard it on the deceleration of the motor. It sounded like it was coming from the header area, not so much the valve cover area. Which I found to be kinda odd seeing as its right there under the valve cover. But it was bent on the lifter side not the rocker side.
06-05-2012, 09:28 AM #8
I popped the valve covers off the other day and nothing visually out of the ordinary. I didnt take out rods as I didnt see an easy way I could get my torque wrench in there to torque them all back down and it would really seem bizarre to be a rod based on the higher tone of the noise than a rod would make and the infrequency that it happens.
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