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intermittent Knocking sound 06gpgt

b4black said:
I haven't watched the videos, but I had a nasty sound thst came and went like you describe. It was a cracked flexplate. There's an inspection plate under the transmission. That it off and look inside. You might see cracks at the "windows". Its a somewhat common problem.
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Yup I agree and I thought OP checked that our first before buying a new motor. Either way. Trans has to come out
 


you need to watch the vids, the knock simply stops. rod knock dont come and go. it knocks and gets worse and worse.

i could see a cold engine with a rod knock not knock till it warmed up, but this starts knocking and stops hot or cold.

same goes for a flex plate. cant see how it can just stop clanging. if its broken, its broken and will be heard. its also not going to fade away. watch the vids.


but a lifter........hmmmmmmmm
 
one can only hope its a lifter, the lesser of the other evils lol

and hes got good oil pressure.

what would really suck is if its a stuck lifter, and the cams rounding out little by little.
 
black06gt said:
Was kinda hard to see in there. Only thing I seen were a couple small lines coming down from the middle of it but I couldn't tell if they were cracks or not.
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You will only be able to see the end of the cracks, but mine went all the way around. Look at the picture below and see if the "small lines" match up with my cracks in the square windows. I'd hate to hear you tore the more all apart when it was just a flexplate.

My sounds came and went for sure. It was actually quieter with the belts off.


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To me it was obvious - at the the cracks, the metal was raw. I didn't do this, but someone suggested unbolting the torque converter and push it aside. Then start the motor and see if the noise is gone.

More reading on my problem (with a video of the noise my engine was making):
http://www.regalgs.org/topic/58610-death-rattle-is-this-terminal/
 

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will let you guys know what it is when i find it out. I had a ASE master tech guy i work with tell me its probably a collasped lifter or multiple lifters. gonna pull the Valve covers off tonight and check for movement on the rockers.
 


Lifter tick is just that - a tick. The knocking sound is one of the options mentioned. Flex plate. Broken lifter. Bearing.
 
time to pick your poison, rip the engine out, or the tranny.

you wont see the cracks, like posted in that other pick its hidden in the curved part and between the windows.


iirc someone once said you can bang the flex plate with a hammer and it should ring, if cracked it wont ring.
 


well after unbolting the tc it made a funny ring with a loose metalic sound. different than before. so im thinking pull the darn thing. if it ends up being that its cracked like its seeming like after this check then ill have it out to replace it and get going with what i wanted to do in the first place. (note) the knock came back after bolting it back up.
 
yeah, its broken for sure then. never seen one just stop knocking tho. very odd. any who. pick what one you want to pull.

the sound you heard when it was unbolted sounds like the tc was rubbing the flex.
 
After less than a year, my flexplate may be bad again. I'll be doing just what you did to find out (unbolting the TC). I rarely take my car to a mechanic, but for this I did. I don't have the time to pull a motor. $450 for labor to drop the trans.

I replaced it with a stock style $50 replacement (Pioneer brand from Rock Auto). After you open up the package, it has a picture and says if the new part cracks around the hub, it's not covered by the warranty. Now I wish I went with a Meziere.

ZZP seems to have the best deal:
http://zzperformance.com/3800/transmission-drivetrain/meziere-billet-flex-plate.html



I also used ARP bolts. Maybe the shop didn't use loctrite on them and they are loose. Next time, I think I'll buy new TTY GM bolts. (Most shops just reuse the old bolts!)
 


b4black said:
After less than a year, my flexplate may be bad again. I'll be doing just what you did to find out (unbolting the TC).
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I hope I'm not thread jacking, but since we same to have the same issue going on.....

I took a look this weekend. I don't see any cracks in the new flexplate. TC bolts were tight, the crank bolts look tight as well. No obvious looseness or wobbles. After unbolting the TC, it still makes noise off and on. Sounds bad!




I'm guessing it's cracked again. :( I don't know what else could be making the noise.
 
Yup mine still comes and goes. I havent had time to pull it apart yet but i do see some rust lines forming from the center of the flex plate like your picture shows. No cracks in the windows though. Its definetly louder at the bell housing area while under the car. If it turns out to be the flex plate (finger crossed) im going with the upgraded one from zzp. Sounds similar in your video to mine while under the car to. Although i could not duplicate it while the TC was unbolted. Only noise i got was when they came back together.
 
@b4black.....Did you ever notice a diference in noise that changed with the gear you were in? Park, reverse, neutral and drive.
 
No, not really. Seems to sound the same in park or gear. Only makes the sounds at idle. Any load and it's quiet. Last time it cracked, I would get a loud "buzz" or "flutter" when I let off the gas. But then that time, the crack went all the way around the hub.

When I had the torque converter unbolted, if I gave the flexplate a whack (like a cymbal), I could here two tones. I would expect to here only one if it were solid.

I ordered a Meziere flexplate yesterday.
 
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