Knock Knock
02-13-2018, 06:56 PM
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Knock Knock Crap, it's LS7 lifters again..
I think...Video is below. The car is cold here. The noise to listen for sounds like a hollow knock. Almost like tires on a bridge. It's intermittent.
Car is a 2008 G8 GT 90k on engine, 50k on build.
Long story short, i heard this noise on my way home from a meeting this afternoon, and my stomach instantly sank.
The car hasn't had DOD for a while. It has a medium sized cam with LS7 lifters.
I checked the oil level when i got home, was about 1/2 a quart off, so i topped it off. I pulled both valve covers, none of the rocker arms have any excessive play.
It was a long trip home this afternoon (about an hour and a half), and even though i babied her, she didn't seem to notice. No loss of power or misfiring.
The noise goes away at around 2k RPM, and gets much quieter as the oil heats up.
So is it time to call CSP and go huge donkey dick cam?
I think...Video is below. The car is cold here. The noise to listen for sounds like a hollow knock. Almost like tires on a bridge. It's intermittent.
Car is a 2008 G8 GT 90k on engine, 50k on build.
Long story short, i heard this noise on my way home from a meeting this afternoon, and my stomach instantly sank.
The car hasn't had DOD for a while. It has a medium sized cam with LS7 lifters.
I checked the oil level when i got home, was about 1/2 a quart off, so i topped it off. I pulled both valve covers, none of the rocker arms have any excessive play.
It was a long trip home this afternoon (about an hour and a half), and even though i babied her, she didn't seem to notice. No loss of power or misfiring.
The noise goes away at around 2k RPM, and gets much quieter as the oil heats up.
So is it time to call CSP and go huge donkey dick cam?
Last edited by Segselah; 02-13-2018 at 07:03 PM.
02-13-2018, 07:21 PM
#2
Hmmmmm, hard to tell but it doesn't really sound like lifters to me. Sounds a little "deeper".
My LS2 developed a similar noise and I thought it was rockers/lifters as well.
Ended up being #6 rod bearing. It would sound so-so at idle, but by 2,000 rpm it started to get louder.
A good test is if you're driving and ease up on the throttle where you aren't accelerating or decelerating, more "neutral" with the throttle, a rod bearing typically gets louder. Under load or decel the rod stays in contact with the crank and doesn't knock as much.
Good luck
My LS2 developed a similar noise and I thought it was rockers/lifters as well.
Ended up being #6 rod bearing. It would sound so-so at idle, but by 2,000 rpm it started to get louder.
A good test is if you're driving and ease up on the throttle where you aren't accelerating or decelerating, more "neutral" with the throttle, a rod bearing typically gets louder. Under load or decel the rod stays in contact with the crank and doesn't knock as much.
Good luck
02-14-2018, 08:56 AM
#3
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Hmmmmm, hard to tell but it doesn't really sound like lifters to me. Sounds a little "deeper".
My LS2 developed a similar noise and I thought it was rockers/lifters as well.
Ended up being #6 rod bearing. It would sound so-so at idle, but by 2,000 rpm it started to get louder.
A good test is if you're driving and ease up on the throttle where you aren't accelerating or decelerating, more "neutral" with the throttle, a rod bearing typically gets louder. Under load or decel the rod stays in contact with the crank and doesn't knock as much.
Good luck
My LS2 developed a similar noise and I thought it was rockers/lifters as well.
Ended up being #6 rod bearing. It would sound so-so at idle, but by 2,000 rpm it started to get louder.
A good test is if you're driving and ease up on the throttle where you aren't accelerating or decelerating, more "neutral" with the throttle, a rod bearing typically gets louder. Under load or decel the rod stays in contact with the crank and doesn't knock as much.
Good luck
Bruh...if you're right...I give up, and there will be a knocking G8 for sale soon.
02-14-2018, 03:12 PM
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Alrighty, i had some time this afternoon to dig a bit more. And i learned a few things
1. It's not a pulley. I pulled the serpentine belt, sound is still there.
2. Did a motor flush, because it werks on da interwebs. Nada
Though i will say the drain plug was nice and clean when i took it out, no metal at all.
3. I have a pretty torque converter (Circle D). It's a shame it's all covered up.
I pulled off the inspection circle to try and wiggle the converter a little (Alex and CSP thought it may be a loose converter bolt). She's all nice a solid from what i could feel.
Before i did the motor flush, i pulled the drivers side valve cover, took off all the rockers and sprayed carb cleaner on the lifters. Fun job i suppose, made me feel all manly. I made sure to do it in the driveway so my haughty neighbors could all see how mechanically inclined I am.
So I'm back at square one. I took a few more videos. The first really shows how loud i can be at idle. That video was while the motor flush was doing its thing...or not...
the second video i said damn the torpedoes and if i blow the welds on the intake, then the mad scientist and I will have to over night some parts from Japan and rebuild the bitch.
But in the second video you can tell how it goes away after some light work. I only took it up to 2k RPM, and it quieted up a lot.
Side note, oil pressure is fat and happy. Never saw anything below 49 psi.
On to the good stuff!
Yes there is some smoke coming off the header. Oil dripped on them while i was taking out the pushrods. No worries.
This is after the motor flush etc. Sorry for the potato camera, my oily fat fingers smudged the lens.
It certainly doesn't get any louder with RPM. In fact it seems to like it. So I dont know what to think.
I have an appointment for the 26th to go up to CSP and have them dig around a little. I guess she'll sit until then. You think it's safe enough to drive up there (about an hour).
1. It's not a pulley. I pulled the serpentine belt, sound is still there.
2. Did a motor flush, because it werks on da interwebs. Nada
Though i will say the drain plug was nice and clean when i took it out, no metal at all.
3. I have a pretty torque converter (Circle D). It's a shame it's all covered up.
I pulled off the inspection circle to try and wiggle the converter a little (Alex and CSP thought it may be a loose converter bolt). She's all nice a solid from what i could feel.
Before i did the motor flush, i pulled the drivers side valve cover, took off all the rockers and sprayed carb cleaner on the lifters. Fun job i suppose, made me feel all manly. I made sure to do it in the driveway so my haughty neighbors could all see how mechanically inclined I am.
So I'm back at square one. I took a few more videos. The first really shows how loud i can be at idle. That video was while the motor flush was doing its thing...or not...
the second video i said damn the torpedoes and if i blow the welds on the intake, then the mad scientist and I will have to over night some parts from Japan and rebuild the bitch.
But in the second video you can tell how it goes away after some light work. I only took it up to 2k RPM, and it quieted up a lot.
Side note, oil pressure is fat and happy. Never saw anything below 49 psi.
On to the good stuff!
Yes there is some smoke coming off the header. Oil dripped on them while i was taking out the pushrods. No worries.
This is after the motor flush etc. Sorry for the potato camera, my oily fat fingers smudged the lens.
It certainly doesn't get any louder with RPM. In fact it seems to like it. So I dont know what to think.
I have an appointment for the 26th to go up to CSP and have them dig around a little. I guess she'll sit until then. You think it's safe enough to drive up there (about an hour).
02-14-2018, 05:13 PM
#6
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Was your trans ever tuned for that torque converter? It could be your thrust bearing... At least, for your sake, I hope it isn't. Too much pressure in the torque converter will cause it to push hard (too hard) into the flexplate, which can smoke a thrust bearing.
It's easy to check. Just attach a dial indicator somewhere in the front of your engine so that the needle sits on your damper. Push it back and forth and see how much movement you have. You may have to pry on it a little (A LITTLE) to get it to move. It SHOULD move. Just not more than about .008". If it's more, it still probably won't knock, as some have said they had .015" and no noises.
It would be similar in symptoms to a thrust bearing, (the center bearing for your crankshaft #3) as in at idle the crank can "walk around" and rub a little like that. But as soon as you get some pressure to the TC, it pushed forward and stops it from moving back and forth.
It's worth checking, and free, unless you have to buy a dial indicator. They are about $40 at harbor freight.
It's easy to check. Just attach a dial indicator somewhere in the front of your engine so that the needle sits on your damper. Push it back and forth and see how much movement you have. You may have to pry on it a little (A LITTLE) to get it to move. It SHOULD move. Just not more than about .008". If it's more, it still probably won't knock, as some have said they had .015" and no noises.
It would be similar in symptoms to a thrust bearing, (the center bearing for your crankshaft #3) as in at idle the crank can "walk around" and rub a little like that. But as soon as you get some pressure to the TC, it pushed forward and stops it from moving back and forth.
It's worth checking, and free, unless you have to buy a dial indicator. They are about $40 at harbor freight.
02-15-2018, 10:08 AM
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Was your trans ever tuned for that torque converter? It could be your thrust bearing... At least, for your sake, I hope it isn't. Too much pressure in the torque converter will cause it to push hard (too hard) into the flexplate, which can smoke a thrust bearing.
It's easy to check. Just attach a dial indicator somewhere in the front of your engine so that the needle sits on your damper. Push it back and forth and see how much movement you have. You may have to pry on it a little (A LITTLE) to get it to move. It SHOULD move. Just not more than about .008". If it's more, it still probably won't knock, as some have said they had .015" and no noises.
It would be similar in symptoms to a thrust bearing, (the center bearing for your crankshaft #3) as in at idle the crank can "walk around" and rub a little like that. But as soon as you get some pressure to the TC, it pushed forward and stops it from moving back and forth.
It's worth checking, and free, unless you have to buy a dial indicator. They are about $40 at harbor freight.
It's easy to check. Just attach a dial indicator somewhere in the front of your engine so that the needle sits on your damper. Push it back and forth and see how much movement you have. You may have to pry on it a little (A LITTLE) to get it to move. It SHOULD move. Just not more than about .008". If it's more, it still probably won't knock, as some have said they had .015" and no noises.
It would be similar in symptoms to a thrust bearing, (the center bearing for your crankshaft #3) as in at idle the crank can "walk around" and rub a little like that. But as soon as you get some pressure to the TC, it pushed forward and stops it from moving back and forth.
It's worth checking, and free, unless you have to buy a dial indicator. They are about $40 at harbor freight.
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02-15-2018, 10:32 AM
#8
TECH Fanatic
Yep, car was built by RPM who did all the engine work and installed the converter at same time. Since then I've also had it returned at Complete Street Performance who did a trans tune as well. I can't imagine having all the work i have done and a 3200 stall without a tune, that must run like crap.
02-15-2018, 11:58 AM
#9
Staging Lane
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Oh, and to the above question about oil. I've only ever used 5w-40 T6 in it. Though the oil change yesterday was a 0w-40, but meh.
02-16-2018, 12:54 PM
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Welp. Today is a good day. My wife stayed home from work so I got some time to poke around some more. I THINK she's fixed.
Have a listen.
Sounds fat, dumb, and lopey to me.
The only thing i found this morning was an exhaust leak at the axle backs. The gaskets were blown, and the bolts were loose. So i picked up some new gaskets and went all Arnold tight on the bolts. Exhaust leak fixed and knocking cleared up.
So, from what i can figure. The exhaust leak was pinging through the exhaust system and amplifying it. I have an appointment with CSP on the 26th, that I'll keep for the time being. But I'll drive it around some this week, the weather should be nice, and see if she starts acting up anymore.
Stupid cars...i shoulda bought a Kia.
Have a listen.
Sounds fat, dumb, and lopey to me.
The only thing i found this morning was an exhaust leak at the axle backs. The gaskets were blown, and the bolts were loose. So i picked up some new gaskets and went all Arnold tight on the bolts. Exhaust leak fixed and knocking cleared up.
So, from what i can figure. The exhaust leak was pinging through the exhaust system and amplifying it. I have an appointment with CSP on the 26th, that I'll keep for the time being. But I'll drive it around some this week, the weather should be nice, and see if she starts acting up anymore.
Stupid cars...i shoulda bought a Kia.
02-22-2018, 09:49 AM
#12
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No, unless it needs a rebuild. The car already has a CSP tune in it.
And, as i kinda thought. I was all too good to be true, and she's knocking again. I have no idea what's wrong with this hunk of crap. So, she'll sit until Monday morning when i go see the doc.
03-04-2018, 06:14 PM
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Noticed the sound was louder when you moved over to the passenger side of the engine.