Jonblarc7

Today cursing down the Hwy today at 75 mph my truck started knock really loud. I thought sh$@ it's about to go, it was loud enough for my wife to ask what is that noise and never pay attention to stuff like that. As soon as I heard it I let of the gas and it went away. Then when I gave gas again it came back. I was right at my exit and I need gas so I pulled in to the closes one and left it running while I filled up and popped the hood.

But it sounded fine by then. Even when I revved it there was no knock. So I drove it home down the Hwy with out it happen again.


What could have made that sound. That was directly related to the RPMs. Then just stop, you think something bad is going on and it's going to come back and I'm going to lose my 6.2. It's an 08 6.2 Denali with 140k on the clock. With headers and a custom tune.

Jonblarc7

The only thing I notice different about the truck lately is when I start it rattles loud like the exhaust is hitting something but stops after the first 2 second and doesn't come back until the next time I crank it.

Do you think maybe something isn't getting oil when I first crank it. Then the oil supply returns.

FFDP

iTrader: (2)

Lifters will do that for sure.

Jonblarc7

I would have to pull the heads to check that??

Should I drain the oil to see if there is any metal shavings?

Three6GMC

iTrader: (11)

I had that issue once but it was right after filling up. No load ran fine but under a load like coming up a hill would knock real bad. Ended up finding out the store I got fuel from had a bunch of diesel in its gas tanks. Smelt like a weed eater at idle. Drained the tank and refilled with good 93 and truck ran fine again.

Mconcha

iTrader: (1)

I had identical symptoms right before my lifters went. Happened on the highway too and my wife had a similar reaction, which she never does. Must be a lifter-highway-wife conundrum.

Hopefully..it's just the fuel like Three6GMC said.

madmann26

iTrader: (7)

Yes, you have to pull the heads off. Dunno about the oil.

Jonblarc7

Well lets just hope it's gas. I was on E went it happen, but man it just didn't sound good. And when it's got louder as I gave it gas I thought man I'm going to have to figure out my option for a rebuild.

If you had a 6.2 that let go what would you do to rebuild it that is budget friendly. Stroke it or buy a new block. Or just find a junk yard 6.2 because it's good enough. I pull a pretty big boat a lot with this truck.

Mconcha

iTrader: (1)

Depends...How long do you plan on keeping the truck? Did you have plans of doing future mods before this happened?

If you LOVE the truck and have no other issues, I'd go straight for a crate ls3 ($5,800), swap your accessories and intake over, tune, then be done and back on the road. Then sell the l92 "as is" and get some money back.
Maybe it's a terrible idea but I'm a simple man and like the idea of having a brand new engine with a warranty and no hassles.

Jonblarc7

The plan is to drop a Stock 48 boost friendly cam in it, my Christmas present from the wife that is boost friendly. Then boost it next year but if the engine lets go, there go the funds for boost.