Knocking sound ??

[Cam @ M&M Racing]

I have a 2004.5 LLY with the PPE, Silverline exhaust, and S&B intake. I have the PPE on power level 3. I pull a 40' 15,000# trailer. The temp gauge is staying at or below 180 not pulling the trailer. I have noticed my engine knocks at around 2000 rpm's. It sounds like it needs a valve adjustment. I have not replaced the fuel filter yet but it is next on the list. Any experience with this? Clogged injectors?? If you punch the throttle, it will still rip! Thanks, Cam

[deadsquirrel]

could just be the pilot injection cycle going off... kind of sounds rattley

[Cam @ M&M Racing]

If I am on a gentle incline holding at 2000 rpm's, it will continue to rattle until I accelerate or let off the throttle. If it were one of my 4 stroke motorcycle engines, it would be a loose cam chain or valves needing adjusting.........

[onesmokinduramax]

Originally Posted by Cam @ M&M Racing

I have a 2004.5 LLY with the PPE, Silverline exhaust, and S&B intake. I have the PPE on power level 3. I pull a 40' 15,000# trailer. The temp gauge is staying at or below 180 not pulling the trailer. I have noticed my engine knocks at around 2000 rpm's. It sounds like it needs a valve adjustment. I have not replaced the fuel filter yet but it is next on the list. Any experience with this? Clogged injectors?? If you punch the throttle, it will still rip! Thanks, Cam

Mine is doin this to im not sure what it could be.

[2005lly]

MIne seems to do the same from time to time, I talked to one of the guys at the performance shop where I get my parts from and he said it could be just junk fuel. My truck did it the other day and I put in a whole bunch of fuel conditioner and suspected that it could've been junk fuel or because my wife let the tank level go just below 1/4 tank i suspect some condensation could accumulated in the tank, went and filled the truck up and added some conditioner and it went away. It's been -30c or better here for the last couple of weeks. Mine seems to go away if you either let off the throttle or slowly ease through it. Hope this helps.

[Cam @ M&M Racing]

I use my truck for long hauls so I typically run the truck until the fuel light comes on and then fill up. I changed the fuel filter and saw quite a bit of junk, water, dirt, etc.... Is there a particular brand of fuel conditioner/injector cleaner people recommend? Thanks, Cam

[2005lly]

I'm using gen 49d right now and it seems to do the trick I've also heard of howes too. I'm using the gen 49d and I'm happy with it.

[DuramaxDudeLLY]

I've seen the same issue in my 04.5...Junk fuel is my belief too. I add a little Lucas Oil injector treatment when this problem arises and it typically clears it up. If nothing else other diesel additives will help. Diesel Power Magazine had a really good article about the (low) quality of fuel that has entered the market. I thin it was in the Sept. or Oct. '07 issue. Just beware of filling up at stations which likely don't sell much diesel, such as suburb type stations which cater primairly to TDI Jetta's and ancient MB 300TD's. I try to always fill up at a truck stop where a) the hoses are bigger, and b) they move a lot of diesel on a daily basis (fuel doesn't have much of a chance to go bad). But, junk fuel or not the ol' DMAX still kicks the pants off my buddies 'Stroke.

[duramaxin14]

Mine does it all the time. Its just the advancement in pilot injection causeing my rattle

[Cam @ M&M Racing]

It was fuel. Put good fuel and injector cleaner in it and the noise went away. Thanks, Cam