"knocking" noise

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Jan 3, 2002 | 10:08 AM

millersnva1

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"knocking" noise

Occassionally, when starting the truck (4.6 L expy) there is a "knocking" sound coming from the engine. It quits after 10 or so seconds. Sounds too deep to be a tappet, but I'm not sure. Truck runs fine otherwise (except for a possible 4x4 problem. see post below)
TIA
tony

Jan 3, 2002 | 10:58 AM

buzzard

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Sounds like piston slap. Do a search in the 4.6/5.4L engine forum.

Jan 4, 2002 | 08:58 AM

millersnva1

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"knocking" noise

Thanks for the reference. I'm worried about the references to replacing the engine, but is it necessary? How long will can this issue ride before it becomes chronic?
tm

Jan 4, 2002 | 02:58 PM

buzzard

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"knocking" noise

Some argue that it doesn't hurt a thing while others won't tolerate it. I would fall into the latter category if mine were acting up.

Jan 5, 2002 | 11:12 PM

Electric1

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"knocking" noise

I'm not so sure this noise is a piston slap, I have the same problem, it knocks once every 100 startups or so, overnight setting cold only, not everytime, in a diesel engine the knock is created by injectors that are pissing straight instead of atomizing, or possibly injector that has leaked off and laid alot of fuel on the piston, it sounds deep but goes away and runs good. Have not gotten to the bottom of it.
Maybe our knocks are different? Electric1