Hi guys I have a 2001 silverado with 208,xxx miles its been a great truck. It has had some noises for a long time 50,xxx miles ago is around when they started.
when i start it and its cold it has a knock to it and I hear this is common on 99-02 5.3's I was wondering if anyone has stopped the problem or has a solution?
I use 1 quart of lucas oil stabilizer every oil change and that helps. I am going to try an engine flush that worked well on moms car next oil change.
any oil additive or other suggestions? thanks

 

Just ole pistol slap.. just keep driving, theres really no cheap easy fix.

 

I dont know if your noise is the same as the noise I had...
I bought an 05 with 135xxx on a 5.3, on start up and here and there while driving. It sound more like a stuck lifter then a knock. I used lucus and 20/50 royal purple and it worked for about 6 to 8 monthes. Then I started losing oil pressure every once in a while when it was cold. Over time evey once in a while turned into every time it was cold and at idle and here and there while cold. I know the "O" ring on the oil pick up tube is a rather common failure but I went ahead and got a GM preformance high volume oil pump. I installed my self and the parts cost me less then 200 from summit. Now its a month later no more tick at all and no more oil problems. I dont know if this will help or if it is just a clearance issue in an older motor, hard to say for sure without seeing/hearing your truck.

 

my 5.3 with 162k sounds like a diesel when I start it up and for about the first 2 minutes it's running before it stops. If your sound is like that and goes away, then its likely the GM piston slap and not an issue to worry about.

My oil pressure is 'good' and I'm unaware of any other mechanical issues, so if your noise doesn't go away, or it doesn't sound like a diesel, then maybe it isn't piston slap.