I've got a 2003 LL8 that's developed a knock. Sounds like one piston. Knocks for 1 second when cold. Not at all until warmed up to operating temperature. Never run on low oil pressure but the owner states he did run it a few quarts low on oil. These hold 7 quarts by the way. Owner added 3 quarts but maintains a diligent viewer of gauges and at no time ran lower than 45 PSI at idle. Owner drives the vehicle like a granny because of poor gas mileage. Knock developed at around 80,070 miles and has not gotten worse. The engine idles smoothly performance is not effected. No smoke out the tailpipe.
My backyard mechanic interpretation is a wrist pin bearing or rod bearing around the journal is out of tolerance. If you accelerate there is minimal noise until you back off the throttle slightly and minimize torque then the knock increases until drivetrain drag puts torque back on the crank and the knock then diminishes.
My proposed repair is to replace all 6 pistons sets from the crank up including rings.
Question is; is their a decent publication that will show me nut and bolt torque specification? I have the tools and the experience in pushrod type
4 cyl motors to do this work but am a bit concerned of the DOHC and VVT. Plus all aluminum construction. Also if the rings are new will I have to score the cylinders so the new rings seat properly? I do intend to mic the crank journals to see if they are in-spec.Any advice will be appreciated.