Overfilled 5.3L Tahoe oil - started knocking on cold starts

[doublebase]

Honestly, I'd find it strange if I didn't hear some sort of knocking from a 2008 5.3 with over 250,000 miles on it!

Whatever you did to get it that far - with everything original - is good work by you.

 

[pacem]

when overnight cold, it taps for about 9-10 seconds, I timed it.
When warm, doesn't tap at all.
I don't understand how a filter can drain given it's mounted vertically under the engine and is therefore full of oil at all times.

 

[carviewsonic]

Sounds exactly like the piston slap my '04 Chev 5.3 company truck developed at around 250,000 kms or 150,000 miles. Soft knocking sound only when cold for about 30 - 60 seconds. That truck stayed in the fleet as a crew truck for a few more years and probably another 100,000 kms after I was assigned a new one.

 

[ZeeOSix]

when overnight cold, it taps for about 9-10 seconds, I timed it.
When warm, doesn't tap at all.
I don't understand how a filter can drain given it's mounted vertically under the engine and is therefore full of oil at all times.

The oil galleries above the oil filter can still drain down if the filter ADBV is leaking. All oil located above the oil level in the sump wants to drain back down to the sump from gravity, regardless of the filter mount orientation.