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-   -   LLY: 04 duramx leaking oil and knocking, please help (https://www.duramaxdiesels.com/forum/showthread.php?t=25907)

04lly 09-08-2010 09:22 AM

04 duramx leaking oil and knocking, please help
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.


TrentNell 09-08-2010 02:52 PM

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 .

04lly 09-08-2010 03:18 PM

is says lly in the post, but theres no white smoke just black, and ill have to get somethin to check the fuel rail pressure.

04lly 09-10-2010 12:18 PM

how much pressure should it be running?

stacks04 09-10-2010 12:49 PM

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.

DIESELMAFIAPER.LB7 09-10-2010 01:58 PM

Sounds like a rear main leak if Its at the back on the trans is the oil way full? hows oil pressure? Also a GM tech 2 will let you watch rail pressure

04lly 09-10-2010 04:14 PM

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.

05lly2500hd 09-12-2010 09:20 AM


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04lly 09-20-2010 05:52 PM

sorry guys, got caught up doing some stuff lately, heres the video link its not the best video but if you turn it up you can hear the knock.


jonathancasey19 09-20-2010 06:20 PM

whoaaa that sounds horrible.... i hope someone on here can help you out. sry ab the bad luck :(

05lly2500hd 09-20-2010 08:55 PM

OUCH! doesn't sound good...where you located? what's your oil pressure?

04lly 09-20-2010 09:13 PM

ya i know im hoping. im in scottsdale arizona, and i believe it was about 30 psi at idle.

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