Knock Update

[TxDoc]

Info - Engine Knock on Cold Start #01-06-01-028 [b/]

 

Engine Knock on Cold Start

 

1999-2002 Chevrolet and GMC C/K Pickup and Utility Models

 

2002 Cadillac Esclade (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) 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 noticable on the initial start-up when the temperature is below 10 degrees C (50 degreees 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 questoins or concerns, please advise your Area Service Manager.

 

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Info - Engine Knock on Cold Start #01-06-01-022

 

Information on Engine Knock on Cold Start

 

2001-2001 Chevorlet and GMC C/K Pickup and Utility Models with 6.0L engine (VIN U -- RPO LQ4)

 

Some of the above vehicles may exhibit an engine knock noise that begins in the first several thousand miles/kilometers of use. The knock noise is most often noticed durign initial star-up and typically disappears as the engine warms up. The noise is usually more noticeable on the initial start-up when the temperature is below 10 degrees C (50 degrees F) or if the vehicle has not been used for several days.

 

This noise may be caused by an interaction between the piston and cylinder wall. GM Powertrain Engineering, and an analysis of engines returned with this condition, has confirmed that the noise is not detrimental to the performance, reliability or durability of this engine. The noise does not have any effect on the longevity of any of the engine components.

 

**IMPORTANT**

 

AT THIS TIME, REPLACING THE ENGINE ASSEMBLY OR PISTONS WILL NOT ELIMINATE THIS NOISE.

 

Please share the information found on this bulletion with customers who inquire about this condition. In the event that have additional questoins of concerns, please advise them to contact Customer Assistance at the numbers listed below for further information.

 

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This has been an issue sence the first 4.8, 5.3, and 6.0 engines rolled out of the GM factory. As of right now there is no fix for this problem.