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Here is the latest bulletin on the topic. My brother, best friend, my two uncles and I all own newer Silverados. My one uncle has a newer 2002 that does not have the problem. Everyone else does. One GM mechanic told me that it is the lightweight, short skirt design of the piston. It is short enought to twist slightly and slap, especially when carbon build up and the engine is a little cooler. It is a really bad design because if there is a real problem like a bend rod, crooked lifter bent valve or the like, you would just be told that it was a normal sound and you'll just have to live with it. I've got 80,000 on my truck and it still runs fine. I would be interested in hearing from someone that there engine blewup because of that problem.
Engine Knock on Cold Start
1999-2002 Chevrolet and GMC C/K Pickup and Utility Models
2002 Cadillac Escalade (2WD)
with 4.8L, 5.3L or 6.0L Engine (VINs V, T, U -- RPOs LR4, LM7, LQ4)
Some of the above vehicles may exhibit an engine knock noise that begins in the first 19,000-24,000 km (12,000-15,000 mi) of use. The knock noise is most often noticed during initial start-up and typically disappears within the first 5-30 seconds (may last longer in extreme cold temperatures). The noise is usually more noticeable on the initial start-up when the temperature is below 10°C (50°F) and may be more pronounced on the first cold start following a long trip.
This noise may be caused by an interaction between carbon that has formed on the piston, the piston motion and the cylinder wall. GM Powertrain Engineering, and an analysis of engines with this condition, has confirmed that the noise is not detrimental to the performance, reliability or durability of the engine. THIS NOISE DOES NOT HAVE ANY EFFECT ON THE LONGEVITY OF ANY OF THE ENGINE COMPONENTS.
Important
At this time, attempts to repair this condition by replacing the engine assembly or pistons is not recommended.
Please share the information found in this bulletin with customers who inquire about this condition. In the event they have additional questions or concerns, please advise your Area Service Manager.
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