2000TransAmWS6

iTrader: (12)

my truck is a 5.3L and about 2 weeks ago it started knocking on start-up. the reason that i don't think that it is piston slap, is because my TA has piston slap, and always has (and i know what it sounds like). with this 5.3 it has never made noise when it was cold until recently, and also the sound is alot louder.
after about 2 minutes the knock will go away, and all is fine until the truck sits for a couple of hours.

the truck has 151k miles on it, but other than this still runs fine.

i can't seem to pin-point where the sound is coming from.
i was wondering if it was a lifter.

any help would be appreciated!
Thanks.

01WS6/tamu

iTrader: (37)

Probably has a wristpin etc starting to head south. I had a 5.3 in the shop with a similar problem and found a cracked piston when I did an autopsy. Put in a new gm engine and was quiet as a church mouse. I'd use the opportunity to step up to a 6.0 and call it a day.

2000TransAmWS6

iTrader: (12)

6.0... thats what i was thinking

anyone else have any ideas?

2000TransAmWS6

iTrader: (12)

something that i forgot to note, the truck has been slowly losing coolant with no signs of coolant on the driveway.

Z Fury

iTrader: (1)

That is usually a sign of an internal engine problem. 6L LQ9 time. I'm leaning that way myself for my truck.

01WS6/tamu

iTrader: (37)

There is a gm service bulletin that gm released for the coolant loss issue. It is porosity in the cylinder heads. The coolant leaks internal to the engine in the valve cover area but it is in small amounts so it evaporates off with engine heat before it is detectable.