flywheel or rod?
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flywheel or rod?
Can a broken flywheel sound like a rod knocking? I had a small tick before, but my start went out and and after I replaced it, it is knocking and rattling something awful. I pulled the inspection plate off but cant tell anything. It is a 6.8
Cargo Master
Joined: Jun 2008
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From: Stillwater, OK
by flywheel do you mean flexplate?
...and yes. If you somehow broke the flexplate and there is a piece that swings around and hits the block once per revolution it will sound similar to a rod, but you should be able to see something very out of place when you look at it.
If you managed to break a flywheel, be careful when you take the clutch off. The flyweel will fall out in separate pieces, but I don't think the truck would be operable with a broken flywheel. If it does start, the pressure from the clutch would probably not be sufficent to get moving without noticing a large amount of slippage. The sharp edges of the shattered flywheel would likely shred the friction material, and before long hot pieces of clutch and cast iron will release themselves from service and into flight.
...and yes. If you somehow broke the flexplate and there is a piece that swings around and hits the block once per revolution it will sound similar to a rod, but you should be able to see something very out of place when you look at it.
If you managed to break a flywheel, be careful when you take the clutch off. The flyweel will fall out in separate pieces, but I don't think the truck would be operable with a broken flywheel. If it does start, the pressure from the clutch would probably not be sufficent to get moving without noticing a large amount of slippage. The sharp edges of the shattered flywheel would likely shred the friction material, and before long hot pieces of clutch and cast iron will release themselves from service and into flight.
Cargo Master
Joined: Feb 2011
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From: Forest lake minnesota
I had a chevy once ( i really hate to admit that ) and it was an auto so it had a flex plate no flywheel , the flex plate cracked and it mad a knocking sound. Did you turn the engine over and listen to the flywheel ?
Senior User
Joined: Sep 2010
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its more likely that you have a LOOSE flexplate or flywheel.
it will sound like a rod knock but only show up at certain rpms or combinations of drive, park and reverse depending on how loose it is. and it will drive you crazy.
personal experience with another car.
to tighten it, get yourself a long pry bar and wedge it into the teeth of the flywheel then torque each bolt down as hard as you can.
im sure there is a torque spec for these bolts, but they are big enough that i'd just go for tight as you can comfortably get it.
if they are all tight, and its not broken (you will see it when spinning it around by hand with the battery disconnected to prevent any accidental starting) then you have a real problem
it will sound like a rod knock but only show up at certain rpms or combinations of drive, park and reverse depending on how loose it is. and it will drive you crazy.
personal experience with another car.
to tighten it, get yourself a long pry bar and wedge it into the teeth of the flywheel then torque each bolt down as hard as you can.
im sure there is a torque spec for these bolts, but they are big enough that i'd just go for tight as you can comfortably get it.
if they are all tight, and its not broken (you will see it when spinning it around by hand with the battery disconnected to prevent any accidental starting) then you have a real problem
Junior User
Joined: Jul 2010
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Sorry but I would have to go with a cracked flex plate....Generally you will find that they have cracked around the center hub of the plate and will definitely sound like a rod that has taken a dump and sometimes even worse....It is not uncommon to the 6.8L....Personally I would bet $5 on it being cracked....
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