i guess that chevy heard a knocking sound coming from my engine. they have had the truck for 3 days now and they cant seem to find out where its coming from. now they are calling gm to help them out. anyone got any ideas. i personally havent heard this "sound".

Hello, I have a 2005 Chevey Duramax 2500 and ever since I bought it new there is a ticking niose coming from the engine. I notice it more at low speeds when the tach is showing below 2000 rpms. it goes away if the tach is above 2000. I will notice it again at crusing speeds when the tach is between 1600 and 1900 rpms. I have taken it to the chevy dealer and they have placed sensors through out the engine compartment and have not been able to determine where the noise is coming from. do you have any ideas. they even had me try a additive to see if thet would help. no such luck. let me know thanks.