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

Sounds like rod knock - from the trans?

Thread Tools
 
Search this Thread
 
Old 05-07-2011, 07:29 PM
  #1  
TECH Enthusiast
Thread Starter
 
Glenn98ZM6's Avatar
 
Join Date: Nov 2001
Location: DFW, Texas
Posts: 702
Likes: 0
Received 0 Likes on 0 Posts
Default Sounds like rod knock - from the trans?

2001 2500HD 4x4 6.0ltr 4L80 crew cab

Got home from a long trip last week. Got outof the truck and heard what I thought was a valve train issue. Parked the truck and walked away for a week. Crawled under it while idling yesterday and the noise sounded like it was at the flywheel. The "knock" is constant at this point.
Put the truck inthe garage to investigate deaper today and at first it was constant at idle, but went away w/ some rpm's. Got under it today and it really sounds like it is coming from the trans. It also is not constant w/ the idle rpm. It will do it randomly now. Sometimes w/ more RPM, sometime not at all.
What in the trans could cause this?
My plan is to drop the dust cover and disconnect the converter from the flywheel and see if it still does it.
Old 05-07-2011, 07:36 PM
  #2  
TECH Fanatic
iTrader: (13)
 
mhotrodscooter's Avatar
 
Join Date: Apr 2010
Location: jennings,louisiana
Posts: 1,750
Likes: 0
Received 0 Likes on 0 Posts
Default

Sounds like this?


http://www.youtube.com/watch?v=kxbYh...e_gdata_player

This was a cracked flywheel.
Old 05-07-2011, 08:33 PM
  #3  
TECH Enthusiast
Thread Starter
 
Glenn98ZM6's Avatar
 
Join Date: Nov 2001
Location: DFW, Texas
Posts: 702
Likes: 0
Received 0 Likes on 0 Posts
Default

Sort of.
I got the cover off and rotoated the flywheel and I couldn't see any issues w/ it.

How in the hell do you get the converter bolts out?
Old 05-07-2011, 08:48 PM
  #4  
TECH Enthusiast
Thread Starter
 
Glenn98ZM6's Avatar
 
Join Date: Nov 2001
Location: DFW, Texas
Posts: 702
Likes: 0
Received 0 Likes on 0 Posts
Default

That vid has more of a scraping sound to it. Mine is more of a ticking.
Old 05-07-2011, 08:55 PM
  #5  
TECH Fanatic
iTrader: (13)
 
mhotrodscooter's Avatar
 
Join Date: Apr 2010
Location: jennings,louisiana
Posts: 1,750
Likes: 0
Received 0 Likes on 0 Posts
Default

I could only tell the flex plate was cracked by little hair line cracks in the round circles of flex plate.

You'll have to pull the starter to get to converter bolts
Old 05-07-2011, 09:24 PM
  #6  
TECH Fanatic
iTrader: (13)
 
mhotrodscooter's Avatar
 
Join Date: Apr 2010
Location: jennings,louisiana
Posts: 1,750
Likes: 0
Received 0 Likes on 0 Posts
Default

Flex plate
Old 05-07-2011, 09:48 PM
  #7  
TECH Enthusiast
Thread Starter
 
Glenn98ZM6's Avatar
 
Join Date: Nov 2001
Location: DFW, Texas
Posts: 702
Likes: 0
Received 0 Likes on 0 Posts
Default

I got the converter disconnected and it does not make the sound now. I guess it is external of the motor.

Who makes a good replacement?
Old 05-07-2011, 10:11 PM
  #8  
TECH Fanatic
iTrader: (13)
 
mhotrodscooter's Avatar
 
Join Date: Apr 2010
Location: jennings,louisiana
Posts: 1,750
Likes: 0
Received 0 Likes on 0 Posts
Default

Good replacement for what? Flexplate?
Old 05-07-2011, 10:42 PM
  #9  
11 Second Hall Moniter
iTrader: (22)
 
AKlowriderZ71's Avatar
 
Join Date: May 2008
Location: Wyoming
Posts: 11,651
Received 8 Likes on 8 Posts
Default

I'm starting to hear banjo's playing.....

I think you should check the flexplate.

Last edited by AKlowriderZ71; 05-07-2011 at 11:35 PM.
Old 05-07-2011, 10:51 PM
  #10  
TECH Enthusiast
Thread Starter
 
Glenn98ZM6's Avatar
 
Join Date: Nov 2001
Location: DFW, Texas
Posts: 702
Likes: 0
Received 0 Likes on 0 Posts
Default

Yes the flexplate.
I also was finally able to see the crack. I connected everything back up and the knock was back. I need to have it drivable so I can get it to my buddy's shop to use his lift and trans jack to swap the flexplate out.


Quick Reply: Sounds like rod knock - from the trans?



All times are GMT -5. The time now is 09:06 AM.