OS Vortec 5300 ?

[GlennBrittain]

I realize this is off the subject of this board, however I feel like there are members that this post applies to. I recently had two problems with my wife’s 2003 Z71 Tahoe, with a Vortec 5300 Flex Fuel. The first problem was the four wheel drive went out, no light on the dash to indicate what state the drive was in either. The part (module 4.563) was $275.28, and the labor was 229.50 to install it. I did purchase an extended warranty which covered all but the first $100.00. Needles to say I ordered a shop manual.
The second problem was a knocking sound when first started. This was explained as a carbon build up on the pistons. I was charged $6.74 for a can of carburetor cleaner and $79.95 to pull the plugs and put the cleaner directly into the cylinders.
Has anyone had a similar problem with the knocking or heard of this problem, not sure if I trust this dealers service department.
If anyone has a similar problem with their 4WD, they can contact me, via email for replacement info, I should have the shop manual soon.