Engine tap (top end)

Ok people. IS it just me or what? As most of you know, at 90K my truck had to have the engine replaced. Done deal, found a used engine with low mileage, swapped it in, ran fine. WELL now, I have about...105K on the truck and aprox. 65 - 75K on the engine. It has developed a tap, or knock (cant distinguish, sounds like both) in the top end of the engine, almost sounds like its in the drivers side head. It ONLY does this after it's warmed up, and its ANNOYING the crap out of me. I don't think it's a valve, but can't be sure yet. DOn't really know how to check it. I'm guessing it's a lifter, or pushrod. I DO NOT want to have to tear the top end down on this engine like I had to my old one. Is there any thing I can do to silence this sound? WOuld flushing the engine help, or maybe some oil additive? I've used nothing but Chevron 5w30 until my last oil change, then I swapped to Valvoline high mileage 5w30. It was doing it before the oil change, so that's not it.
Any ideas??

I'm very dissapointed with this Chevy. I've had 3 Ford's and had NO problems out of them, no matter how much hell I gave them. I try to baby this truck b/c it's the newest one I've ever had and its falling apart. Don't expect I'll buy another one.

is it the famed piston slap, or maybe a colapsed lifter, try flushing the oil system

I don't think it's piston slap, it sounds more like a lifter, or valve, but I'm not sure.

Have you thought about trying a can of Sea Foam or similar product?

try and narrow it down with the screwdriver/stethoscope trick, you said it happens after it warms up maybe you have a chunk of carbon thats giving you a preignition knock, maybe some top engine cleaner

ever thought maybe its has had enough of that nelson performance "hot" tune???

Ok people. IS it just me or what? As most of you know, at 90K my truck had to have the engine replaced. Done deal, found a used engine with low mileage, swapped it in, ran fine. WELL now, I have about...105K on the truck and aprox. 65 - 75K on the engine. It has developed a tap, or knock (cant distinguish, sounds like both) in the top end of the engine, almost sounds like its in the drivers side head. It ONLY does this after it's warmed up, and its ANNOYING the crap out of me. I don't think it's a valve, but can't be sure yet. DOn't really know how to check it. I'm guessing it's a lifter, or pushrod. I DO NOT want to have to tear the top end down on this engine like I had to my old one. Is there any thing I can do to silence this sound? WOuld flushing the engine help, or maybe some oil additive? I've used nothing but Chevron 5w30 until my last oil change, then I swapped to Valvoline high mileage 5w30. It was doing it before the oil change, so that's not it.
Any ideas??

I'm very dissapointed with this Chevy. I've had 3 Ford's and had NO problems out of them, no matter how much hell I gave them. I try to baby this truck b/c it's the newest one I've ever had and its falling apart. Don't expect I'll buy another one.

Do you have any logging hardware/software so you can send Allen a log of what's going on in the computer. It might have something to do with the tune, but I highly doubt it. Looks like you're about ready to make the 6.0L swap! :biggrin:

I think your right. If it goes like the other 5.3, theres no doubt thats what I'm gunna do!
It did something weird last night though. I was going to a call and at one intersection, just gave it hell...held it wide ass open...then realized I was doing 90 in a 35... all that aside, this morning, when I usually crank the truck up to let it warm up a little, the frickin sound was gone! What gives??

ever thought maybe its has had enough of that nelson performance "hot" tune???

Oh, I don't think its the tune either. :grinno: