knocking only when cold started. on a cold day
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Supreme Member
Joined: Dec 2004
Posts: 1,204
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From: chicago IL
Car: 91 formula
Engine: 350 tuned port. bolt ons
Transmission: 700r4
Axle/Gears: 3.73
knocking only when cold started. on a cold day
ok this is my friends 1988 firebird. When he starts the engine you hear a knocking like its the valvetrain or something. it goes away after about 30 seconds. it only happen when it below 40 Degree out. any idea? it a 5.0L fuel injection engine all stock with only 30k miles on it. thanks.
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Joined: Oct 2010
Posts: 22
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From: Erie, Pa
Car: 1987 Iroc Camaro
Engine: 383 GMPP TPI
Transmission: 5 Speed Manual
Axle/Gears: 10 Bolt 4:10 Eaton Posi Moser Axles
Re: knocking only when cold started. on a cold day
It's most likely piston slap, small blocks are notorious for it. The clearance between the piston and the cylinder wall allows the pistons to "slap" the cylinder wall making a knocking noise. Once the pistons warm up they expand and the noise goes away. Nothing to worry about, just try to avoid racing the engine when it's cold.
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