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EG6
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k started hearing a knocking noise in the #4 cycl. if i pull the spark plug from that cycl. it stops... sounds like a hammer hitting it.. metal to metal... could it be a spun berring
 

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Brokedick Millionaire
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k started hearing a knocking noise in the #4 cycl. if i pull the spark plug from that cycl. it stops... sounds like a hammer hitting it.. metal to metal... could it be a spun berring
perfect why to check it........

KNOCK KNOCK......
 

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See above...
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Okay, so I know what a spun bearing is and what causes denotation...but what causes or what is rod knock?
 

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http://zhome.com/ZCMnL/PICS/detonation/detonation.html

Abnormal combustion, more commonly known as knock or detonation, has been the limiting factor in internal combustion engine power generation since the discovery of the otto cycle itself. To tune an engine for maximum power, you need to understand this undesirable yet ever-present problem.

Abnormal combustion manifests in many different ways. To the typical enthusiast, all abnormalities are referred to as knock or detonation. In practice, though, when the undesired flame front is initiated and how it is propagated define the cause and, in turn, the appropriate cure.

Abnormal combustion got the nickname knock from the noise that is transmitted from the colliding of the multiple flame fronts and the increased cylinder pressure that causes the piston, connecting rod and bearings to resonate. Any sort of abnormality in the combustion process has serious consequences in the power output, longevity and emissions generation of an engine.




CAUSES OF PRE-IGNITION

Carbon deposits form a heat barrier and can be a contributing factor to preignition. Other causes include: An overheated spark plug (too hot a heat range for the application). Glowing carbon deposits on a hot exhaust valve (which may mean the valve is running too hot because of poor seating, a weak valve spring or insufficient valve lash).

A sharp edge in the combustion chamber or on top of a piston (rounding sharp edges with a grinder can eliminate this cause).

Sharp edges on valves that were reground improperly (not enough margin left on the edges).

A lean fuel mixture.

Low coolant level, slipping fan clutch, inoperative electric cooling fan or other cooling system problem that causes the engine to run hotter than normal.
 

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Worst Mechanic Ever!
EG
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KNOCK is detonation.

ROD KNOCK is a bent rod that ready to slam through your block.

theres an extra word there, makes a difference.
 

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KNOCK is detonation.

ROD KNOCK is a bent rod that ready to slam through your block.

theres an extra word there, makes a difference.

rod is likely not bent. the bearing is trashed, possibly spun and way loose causing the rod to knock on the crank. clank clank clank

fyi, if its that bad, the rod and likely crank should be replaced. replacing the bearing only will not fix the problem.
m.
 

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Brokedick Millionaire
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Rod Knock is NOT a spun bearing.

Just a bad bearing.

My Z6 had rod and crank knock, but never spun a bearing.

a "spun bearing" is wear it has worn enough OR got hot enough to seize and the alignment tabs failed to fold of the bearing halves in position.

in short, either way your fucked!
 
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