Engine noise when cold.

[rob56]

HI TO ALL ONCE AGAIN. ON MY YUCON 03 KNOCKING NOISE FROM ENGINE AND MISSING SOUND FROM tail pipe. once warm its fine.

 

[04white-z71]

Broken manifold bolts.

 

[nuc_meltdown]

Piston slap. It's normal.

 

[Physh1]

Probably a broken exhaust manifold bolt or two. Common on these trucks. When cold exhuast may leak out from between the manifold & the block. Take a look at your manifolds & see if you notice any bolt heads missing.

Piston slap shouldn't cause a missing sound out of the exhaust. While another common issue, that goes away after a minute or so, it shouldn't be causing the symptoms you've got.

Cameron

 

[boozer]

Probably a broken exhaust manifold bolt or two. Common on these trucks. When cold exhuast may leak out from between the manifold & the block. Take a look at your manifolds & see if you notice any bolt heads missing.

Piston slap shouldn't cause a missing sound out of the exhaust. While another common issue, that goes away after a minute or so, it shouldn't be causing the symptoms you've got.

Cameron

Piston slap, sounds like **** but normal for the vortec