LS7 engine noise! Need help!
02-12-2019, 12:07 AM
#1
Teching In
Thread Starter
Join Date: Feb 2019
Posts: 5
Likes: 0
Received 0 Likes
on
0 Posts
LS7 engine noise! Need help! 
My 2008 Z06 developed a noise recently I can't seem to figure out. Removed the valve covers and all the rockers and pushrods are fine, engine still makes the noise with the belt removed. Oil pressure seems fine. It sound does get faster with the speed of the engine (when revving it). It's a high pitched knock/tap sound. I'm almost 100% certain it's not a lower end sound. Seems to be more from the top end. I'm thinking possibly a bad lifter? What do you guy think??? Any help is highly appreciated.
02-12-2019, 03:50 PM
#4
ModSquad
iTrader: (6)
If it were mine, I’d pull the oil filter and inspect the filter element for any debris. If it checks out, pre-fill a new one, and install. Your probably aware of the LS7’s issues, being valve guides out of spec, which usually leads to a dropped valve, and the coating on the Ti rods flaking off at the rod shoulders. I don’t think either of the issues is affecting what you’ve got going on here. Hard to diagnose over the internet, but I wouldn’t drive it until it was fixed.
02-12-2019, 05:11 PM
#5
Teching In
Thread Starter
Join Date: Feb 2019
Posts: 5
Likes: 0
Received 0 Likes
on
0 Posts
If it were mine, I’d pull the oil filter and inspect the filter element for any debris. If it checks out, pre-fill a new one, and install. Your probably aware of the LS7’s issues, being valve guides out of spec, which usually leads to a dropped valve, and the coating on the Ti rods flaking off at the rod shoulders. I don’t think either of the issues is affecting what you’ve got going on here. Hard to diagnose over the internet, but I wouldn’t drive it until it was fixed.
02-12-2019, 08:17 PM
#7
If the first heads failed @ 20k, you are now 35k
past that. Did you replace the heads with same?
Can you take an old timing light, and use it to flash compare the frequency of the sound? This could help you identify if upper or lower end.
You could pull each injector connector one by one to see if it is on one cylinder only.
I found a cracked flexplate once on an old 454, made sound you are saying, was nearly impossible to find.
Runs smooth, but I’d still do a compression and leak down on all 8 holes to try and figure it out.
past that. Did you replace the heads with same?
Can you take an old timing light, and use it to flash compare the frequency of the sound? This could help you identify if upper or lower end.
You could pull each injector connector one by one to see if it is on one cylinder only.
I found a cracked flexplate once on an old 454, made sound you are saying, was nearly impossible to find.
Runs smooth, but I’d still do a compression and leak down on all 8 holes to try and figure it out.
Trending Topics
02-12-2019, 09:50 PM
#9
Teching In
Thread Starter
Join Date: Feb 2019
Posts: 5
Likes: 0
Received 0 Likes
on
0 Posts
If the first heads failed @ 20k, you are now 35k
past that. Did you replace the heads with same?
Can you take an old timing light, and use it to flash compare the frequency of the sound? This could help you identify if upper or lower end.
You could pull each injector connector one by one to see if it is on one cylinder only.
I found a cracked flexplate once on an old 454, made sound you are saying, was nearly impossible to find.
Runs smooth, but I’d still do a compression and leak down on all 8 holes to try and figure it out.
past that. Did you replace the heads with same?
Can you take an old timing light, and use it to flash compare the frequency of the sound? This could help you identify if upper or lower end.
You could pull each injector connector one by one to see if it is on one cylinder only.
I found a cracked flexplate once on an old 454, made sound you are saying, was nearly impossible to find.
Runs smooth, but I’d still do a compression and leak down on all 8 holes to try and figure it out.
To me the sound is the same as the revolutions of the engine not the valvetrain which I think would be 1/2 the speed?
We also pulled each plug wire individually with the car on and the noise never changed.
Oil pressure seems good, 50-70 cold and gets no lower than 30 hot
Car runs super smooth and normal. It almost seems like something is just swinging around and hitting something with each revolution. No idea
02-15-2019, 08:47 PM
#10
11 Second Club
iTrader: (3)
"It almost seems like something is just swinging around and hitting something with each revolution."
That's what it sounds like to me also. Not that I'd want to keep running it to diagnose the problem out of fear it's something internal but you may need to invest in an engine stethoscope but before I did anything else I'd verify that all your pulley's are tight and clear/free of obstructions.
That's what it sounds like to me also. Not that I'd want to keep running it to diagnose the problem out of fear it's something internal but you may need to invest in an engine stethoscope but before I did anything else I'd verify that all your pulley's are tight and clear/free of obstructions.
