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RIP Jason
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4,089 Posts
Discussion Starter #1
On my truck when its cold I have noticed a weird knocking sound. Sounds almost like a diseal truck. This continues untill it gets alittle warm or until I run out of time and need to go to school. The sound continues up to about 20mph then goes away and wont come back.
what the hell is wrong with my engine? :bawl:
 

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Drive It Like Ya Stole It
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6,656 Posts
Welcome to the world of GM engine knock. Search the subject as "engine knock" or "engine ping" You will get TONS of info.

Here it is broken down: when the 4.8, 5.3 and 6.0 (same block) was introd GM went to an aluminum block. They used their old manufactoring process to build them. There is a certain tolerence that has to be met to the pistons move horizonatally in the cyliners, and when they went to aluminum this tolerance was cut in half - but they kept the old manufactoring process that only was exact to the OLD tolerances. See the problem? Some trucks get it, some dont. They often claim its from carbon buildup but thats only a small percent of the truth - if the truth at all ins ome cases.
 

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3,518 Posts
Ok, your cylinders were bored too large from the factory. Your piston slaps around inside the cylinder, tearing up the cylinder walls and rings until the piston warms up and expands and makes up for the space. Another reason I'll never buy a new gm...
 

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RIP Jason
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4,089 Posts
Discussion Starter #10
Well everytime i start my damn engine....Looks like engine swap will happen sooner than I thought.
 

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internet bigot®
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4,016 Posts
i said TBI because those are the older motors that were being used in 98 and older. before they switched blocks... i wouldnt suggest doing a motor swap unless you want to drop in a 6.0.
 

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RIP Jason
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4,089 Posts
Discussion Starter #12
Yah...I'm thinking 6.0. I would like a 383 stroker but I'm sure that won't happen.
 

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RIP Jason
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4,089 Posts
Discussion Starter #15
I know the 6.0 is the same block but I would probably find a used block that doesn't have the problem. It's just very annoying leaving my school parking lot and the knocking sound going crazy. I can hear it over my damn 40 series!
 

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Umm, wrong, 96 and up are vortec, not tbi. So you could easily find a 96 or later 350 or 454 vortec. They were good and didn't knock, back when gm made a quality product...
 

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RIP Jason
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4,089 Posts
Discussion Starter #17
Well the new motors are great if they don't have the damn problem. I just wish they sounded like the old TBI's at low RPM. I love that rumble
 

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5.5MPG!!!!!!!All Day Long
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123 Posts
well.......if u want it fixed, it will take a long time and alot of footwork on ur part. i've working on this prob for 8 mos. and it also happens in the 8.1. first, is ur truck still under warranty. if it is u will need to take it to the dealer and get the paper trail started. u also need to research piston slap and know what ur talking abt when u deal with them. after abt 3 times to the dealer with the same problem and u getting more aware of what is actually going on inside ur motor they will refer u to gm customer service to get a case # started. continue to take ur truck to the dealer. they have to take it and log it each time. also, they will tell u its carbon and give u a tsb print out abt it. do what they recommend or have them decarbonize it.(it wont help) more paper trail." u had done what they said would fix it". they will then offer u the 100k mile warranty on ur motor. that is where i am. take that cause it covers the whole motor for 100k. eventually u will start burning more and more oil. go in for an oil consumption evaluation if u notice that u r burning oil and they will log it. then call and speak to an "avm" area vehicle manager that covers the dealers in ur area. he will be the one to make the call on a new motor. it takes alot of time and i am going thru it. if it is only on cold starts....they wont do anything about it.if it is every start they will. mine does it every start for abt 2-3 minutes. i am also really close to my new motor. i am meeting with the avm march 12. good luck. that is how to go abt doing it. its the correct way.....
 

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[>
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3,255 Posts
Hey Big D, just a question.

How much of this back and forth has to happen while you are still under warranty? That make any sence?
I mean, can you make your first Complaint under warranty, then keep doing what you are talking about after the warranty is out?
Just asking

BD
 

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RIP Jason
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Discussion Starter #20
Wish I was under warrenty...I just have to bite the built. Atleast it goes away but is still frustrating.
 
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