Engine Knock - Rod or Flexplate/Flywheel?

[Greg571]

2001 Silverado 1500 HD with 6.0 liter motor.  Has run strong for many years, and not treated like a work truck. Oil changed every 4K to 5k.  Started up and my son head a bang noise and then the knock.  Shut it off.  I then started it, heard the knock.  Pulled off plug wires one at a time and heard no change in the knock.  Hoping it’s the flexplate and not a rod or spun bearing.......can anyone help or make a suggestion??

[davester]

what can anyone say?  it could be all kinds of things.  maybe pull off the cover for the torque converter (there's one if it's a 4l80e, don't know about the 4l60e), and shine a flashlight in there to see if the flexplate looks broken.

[CamGTP]

A spun rod bearing would make glitter in the oil. If the dipstick is still clean, it's not going to a rod/main bearing.

[Brian715]

How's the oil pressure? If its still good less likely to be a rod or main bearing

[swathdiver]

Probably a cracked Flex Plate.  Time to crawl under...

[Greg571]

Guys, thanks much for the input.  Cracked flex plate is quite a bit cheaper than a crate motor. Going to have it checked by a pro on Wednesday.  Got my fingers crossed.  Not a job I can do.....Oil looks clean and pressure is good.  I don’t have the inspection cover on the bell housing though.   Thought about pulling  the starter and plastic shield to take a look....

Edited February 2, 2020 by Greg571

[swathdiver]

16 hours ago, Greg571 said:

Guys, thanks much for the input.  Cracked flex plate is quite a bit cheaper than a crate motor. Going to have it checked by a pro on Wednesday.  Got my fingers crossed.  Not a job I can do.....Oil looks clean and pressure is good.  I don’t have the inspection cover on the bell housing though.   Thought about pulling  the starter and plastic shield to take a look....

Do it, remember the words of Ronaldus Magnus, "doveryay, no proveryay", Trust but verify!

 

Put a wrench on those flex plate bolts and see if they are tight too.  A loose one will make the it sound like the engine is coming apart.

[Gary Hitt]

Did you get the problem resolved? Was it the flywheel?

[davester]

...almost 5 year old thread and the o.p. hasn't logged onto the site since then.  You aren't going to get a response from that user.