GM Drivetrain & Suspension Chassis | Transmission| Driveshaft | Gears/Rear End/Differential | Traction Aids

knocking/metal grinding noise from torque converter

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Old Mar 12, 2014 | 08:55 AM
  #11  
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Noise stays the same no matter what gear its in, whether it's moving or sitting still. Higher rpms it gets louder. I don't dare take it over 2000rpms.
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Old Mar 12, 2014 | 09:27 AM
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Sounds kind of similar to an issue I had...

Cold start rattle - YouTube


My issue turned out to be the starter shield being loose and contacting the flexplate.
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Old Mar 12, 2014 | 11:28 AM
  #13  
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Originally Posted by vipergtrdj
Noise stays the same no matter what gear its in, whether it's moving or sitting still. Higher rpms it gets louder. I don't dare take it over 2000rpms.
If the noise does not change at all, I think your issues might be somewhere else. Maybe a crack in the flexplate you did not see or a starter issue like mentioned above.

Chris
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Old Mar 12, 2014 | 12:21 PM
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I would think if it was inside the converter the piutch and rate of the sound would change directly with the engine RPM. does it just get louder with RPM?
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Old Mar 12, 2014 | 03:28 PM
  #15  
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Originally Posted by Vortec350ss
I would think if it was inside the converter the piutch and rate of the sound would change directly with the engine RPM. does it just get louder with RPM?
the noise changes with higher rpms. The pitch also changes too. sometimes its a banging/knocking and sometimes its a high pitch metal squeeling sound.
I thought about the starter and I've checked everything with that abd ita all good. When I originally had a shop look at it they said they unbolted the converter and pushed it away from the flywheel and started the truck and the noise was gone. So made me believe that something in the converter is bad.
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Old Mar 12, 2014 | 03:57 PM
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When you are in park idling in gear the turbine inside the converter is spinning freely with the rest of the converter. Very little if any slip between the 2. When you drop it in gear you apply the forward clutches which stops the turbine from turning. This is typically when a converter noise will be the worse. Since you do not hear a big difference leads me to believe the noise is not converter related. But if you disconnected it and the noise went away, then that points back to the converter. Going to be interesting.... Good luck

Chris
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Old Mar 13, 2014 | 07:16 PM
  #17  
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Hey Chris
Went to drive the truck to my shop so I could start tearing into it, and not even 300ft from my driveway I lost all moving power. I stopped and crawled underneath and saw that all the torque converter to flywheel bolts, specifically the heads of the bolts were gone. Somehow they were broke off. The threads of the bolts are still in the torque converter, but the heads are all gone. Kind of odd since the other week we rechecked it all and put loctite on the bolts, tightened to the correct lbs per the book, there was also no play in the TC and flywheel. Maybe a bent/bad flywheel? Any ideas what would cause it to shred the bolts like that?

Luckily it did not damage anything internally, took a small piece off the side of the oil pan but didn't puncture the pan at all. I also have a oil pan that I can swap out if I notice more damage.
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Old Mar 16, 2014 | 04:02 AM
  #18  
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Well, sounds like you found your noise.

...Could be as simple as a bolt tapping something it shouldn't....
You could have cracked the bolts without knowing it when you did your retighten.
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Old Mar 19, 2014 | 06:28 AM
  #19  
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Originally Posted by Suburbazine
Well, sounds like you found your noise.



You could have cracked the bolts without knowing it when you did your retighten.
Yeah. Once I pulled the transmission I did find the center of the flywheel was cracked as well.
A little off topic but I got the transmission rebuilt with the Monster in a box stuff and the person who put it all together is a local guy who rebuilds trannys. I was just curious, the input shaft spins and the output shaft is pretty hard to spin. That is normal, right ?
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Old Mar 19, 2014 | 08:59 AM
  #20  
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The output shaft wont spin if you are in park...
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