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I minimized mine by switching to Mobil-1 High Mileage 5W-30. Synthetic oil and has more zinc additive than the regular M-1 synth. Didn't completely eliminate the slap during cold weather, but I have to be listening for it to notice.
That is exactly what my Z71's 5.3L does, then as soon as the coolant temp starts to move above the 160*F mark the noise just stops.
Car goes in for a Rank hi-stall converter either Thursday or first of next week depending on delivery date(never put a car in the shop on a Friday....something goes wrong and it sits 2 days with nothing being done)....
I will have it checked out while there but sounds like piston slap based on most of the posts on this thread...Thanks for all the replys..
One thing I forgot to mention...the click/knock get louder when I put the car in gear (auto)........
The piston slap gets louder with more engine load. Mine does it too. Also my 06 Silverado w/5.3 I used to have did it too. Just let it warm up for a couple minutes before you drive it, putting a load on it when the slapping is going on will just make it worse over time, although I've never heard of any ruined engines because of "the old piston slap". Post your question on a site such as ls1tech and you'll get plenty of responses sayin its piston slap.
In the early production run of the LS-series engine, some engines encountered abnormal amounts of 'piston slap' - a problem caused by too much clearance between the cylinder bore and the piston.[11] 'Piston slap' sometimes sounds more like a knock or the sound of a diesel engine running. It is typically worse when the engine is cold and lessens as the engine reaches operating temperature. The noise of 'piston slap' often is louder when listening for it below the oil pan.
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I have a 2000 Silverado with a 5.3L engine that I bought new that now has 124,xxx miiles and it started the piston slap at ~50,xxx miles. It never burns/uses oil in its 5000 mile oil changes with Mobil 1 but in cold weather sounds like a diesel engine for about 2 minutes while idling.
Though it may not be the OP's actual issue, it sounds a lot like it.
For anyone wanting more information on GM's Piston Slap:
I have an 80 does something like this but I already know what mine is.....leaking exhaust gasket, You might try getting a 2 foot small hose put one end in your ear, take the other end around your exhaust manifolds if you come to a place where it gets louder...you have found it!!
I have an 80 does something like this but I already know what mine is.....leaking exhaust gasket, You might try getting a 2 foot small hose put one end in your ear, take the other end around your exhaust manifolds if you come to a place where it gets louder...you have found it!!
you have an exhaust leak.
op [and i] have piston slap.