Help Diagnose Engine Noise

[fourwheelinfool]

When I start my truck she greats me with "tlick tlick tlick". She keeps repeating that to herself until 1500 rpm or so. When I run up to 2000 rpm and let off the gas, I can hear it again as the truck jumps to a lower rev. This noise stays no matter how long I run the truck.

 

I also have noticed a very faint "whistle" noise coming from the engine at 650 rpm and will appear intermittantly up the higher revs until 2500 rpm. Don't know or have any idea what this is but I do know that it first appeared some time ago. It sounds like a very faint whistle, like if you were blowing air out your teeth. Whistle is the best way to describe what tone it has, but it does not sound "airy".

 

So last night I was probing around my truck with a short peice of tube and have determined two things:

 

1) The "tlick tlick tlick" seem to be louder on the passenger side through the wheel well.

2) That same sound is loudest at my tail pipe! If I put a hose to my ear and the other end at the exhaust I can clearly hear the noise, much better than elsewhere.

3) I have also noticed that the exhaust "whub whub whub" seems to be in exact timing with the "tlick tlick tlick".

 

Does this sound more like an exhaust problem rather than a piston slap problem or both? I didn't consider exhaust before because the "tlick" is not airy, it sounds like the back of a fingernail being tapped in a sliding fashion against a peice of steel.

 

Any thoughts?

[KB06YUKONXL]

Mine ticks until it hits 180 degrees then it stops......drives me crazy in the cold weather. The dealer said "That's normal...they all do that"

[tombstone]

I am having the same problem as the OP. I've been through two sets of lifters, a cam and an oil pump under warranty and the noise still prevails.

 

I've pulled off all belts to eliminate a belt/pulley/accessory problem only to be greeted with the ticking. I'm considering doing the GM top end cleaner next.