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Discussion Starter #1
What usually causes this?

Thanks everyone
Will
 

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the classic 'knock' is from bearings going bad.


When does it do it?

How long does it last?

How loud is it?

Is it tinny or loud?
 

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Discussion Starter #3
My friend has it, its not me. Sorry for sounding like a newb but where are the bearings located in the engine?

Thanks
Will
 

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Umm, I think you're jumping the gun here. Most people think of spark knock first (detonation), which can be solved by adjusting the ignition timing or using colder spark plugs. There are also other things that can make a knocking sound, like piston slap... but that's not too common in 4.6's.
 

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yea.. 'knock' describes a lot of things.. someone people will call sparkknock a knock, though I think of it as more of a ping.. lifters can make noise.. timings chains/gears.. rocker arms, pushrods.. or as someone said 'classic knock' when a bearing spins or goes bad.. can be a gradually louder growing thing or a sudden onset. Really do need more descriptive information before even guessing what any 'knock' could be.
 

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Mom's 4.3L chebby blazer had a piston pin come loose and that knocked like crazy... but I warned her not to buy one... :leftright
 

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are you shure its a knock?? it could be the Injectors, also what gas is he running?, I know you might get a gas knock too if you use crappy gas.
 
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