Lifter noise 02 suburban or piston slap 47000 only after sitting over night cold start?

Answer 1

if you're asking which one is which it needs to be heard to determine , piston slap is more of a deep knocking sound and its usually heard when starting the vehicle after you have stop (red light ,stop sign)if you have a 2002 vehicle it may not be piston slap. lifter noise is more of a light tapping and is louder at the top of the engine.lifter noise its easy to get rid of simply change your oil or check oil level.keep it at recommended level.if after changing oil sound remains you may need a thicker oil.20/40

AnswerI've read some where that there is a valve that holds the oil in the head and when the valve is bad the oil flows back into the oil pan and when left overnite it starts up dry and until the oil pressure comes up there is a sometime loud knocking