LLY: 04 duramx leaking oil and knocking, please help

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04lly

New member
Sep 7, 2010
7
0
0
scottsdale, AZ
Hey my names geoff I have a 04 silverado 2500hd 6.6l lly, it has 120,000 miles on it. this past week i just got back from new mexico and i was pulling down my street and i noticed the truck was making a knocking noise when i let off the gas goin slow. but if i reved it up and went faster it would go away and sound fine. the next day i went out to look at it an started it up an it was still knocking, but if i raised the rpm's it would go away, and there was a trail of oil all down the bottom side of the truck that was coming from the flywheel cover i believe. I am just trying to see if anyone cal help me out with this i have no clue where to start. i scanned it and it threw a couple codes, they were p0299which i think is low boost, p0670 which is a glow plug control circuit an p0700 which im not sure what that one is i think just to tell the computer there is a problem if im wrong on any of these let me know. but if anyone has ideas or has had this happen before an could help me out i would appreciate it. i need my truck for work so i got to get this fixed soon.

thanks
 
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TrentNell

TrentNell

Finally underway !!!!!
Jul 7, 2008
7,543
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slc tuah
Need some more info before we can help , what was the fuel rail pressure ? is there any smoke white or black ? fuel in the oil ? is it a LLY or LB7 ? 2004 is usually LB7 but a few 2004.5's were LLy's . post more omore info and we will see what we can come up with .
 
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stacks04

Member
Nov 16, 2007
792
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16
Terryville,Ct
At idle around 5000psi or so or 30-40mpa. Other than the low rpm knock does it run okay at the same rpm? The fprv is common on the older trucks and will can increase fuel pressure to much but it usually is acompanied by a rough run condition.
 
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04lly

New member
Sep 7, 2010
7
0
0
scottsdale, AZ
ya as soon as i raise the rpms the knock goes away and it runs fine, but as soon as it drops down to idle its a loud knock again. an i smelled the oil on the ground and it is transmission fluid, so i got a couple problems. i scanned it again and it is saying p0090 and u0105. ill get a video up in a bit so you guys can hear what it sounds like.
 
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