Bears4Sho

almost every time that i go to start my 2001 silverado 2500 HD ext cab there is a knocking sound for a minute or so and it goes away, even in the afternoon it does it again, its coming from somewhere in the engine does anyone have any suggestions on what they think it is.

rjeffery

Piston slap. Caused by improper lubrication upon start up. Almost every Silverado has it, so it's nothing to worry about.

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2002 1500 Ext. Cab 4.8L 2wd.
K&N FIPK, Cat Back Exhaust, Rancho RSX Shocks, Silverstar Headlights High & Low, Infinity Reference Door Speakers & 10" Dual Voice Coil Sub. 265/75/16 BFG AT/KO's, Spray-In Bed Liner, Hella FF75 Fog Lights, Hella FF75 Driving Lights.

silverado122775

It does not cause any harm to the engine either.

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2000 Silverado Z71, 5.3L, K&N GenII Air Intake, Y-pipe Exhaust (no muffler), Bosch Platnium +4 plugs.

Bears4Sho

thats cool thats its seems not to be anything to worry about, but is there any way to remedy the problem.

silverado122775

There are some things you can do. Search the Forum for "Piston Slap" and you will read about what some of the people did to help reduce the noise.
Some say certain plugs, others say different oil.

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2000 Silverado Z71, 5.3L, K&N GenII Air Intake, Y-pipe Exhaust (no muffler), Bosch Platnium +4 plugs.