I have noticed that when I accelerate I have a noise from the engine similar to "shaking gravel in a can". I dissapears when I'm off throttle, or just crusing on the highway.


It will do this at any RPM, and I can only hear it with the windows up in cab. The rattle noise is not there at idle


Is this related to the pilot injection?


I've tried a lubricity additive without result.


Is this normal?


Thanks


Rob

Probably the pilot injection. It shuts off at around 2500rpm so I don't know why you say you hear it at any rpm.

I only hear it when I accelerate, doesn't matter what RPM I'm at, foot off, and its gone.


I thought pilot injection was supposed to make things quiet





Rob

My 6.0 powerstroke does the same thing, and I was also wondering what it was. It is just a clatter that you hear when you toe into the throttle. It goes away when you are off of the pedal. I don't think it is related to pilot injection. Edited by: sshaffer

My 6.0 powerstroke does the same thing, and I was also wondering what it was. It is just a clatter that you hear when you toe into the throttle. It goes away when you are off of the pedal. I don't think it is related to pilot injection.




Exactly,


What is it?





Rob

Check your exhaust pipe up close to the motor. There is a small bracket behind the wheel well that breaks away from the exhaust and it's so close together that it rattles. Mine does it while idling, during acceleration & deceleration. I have welded it 2 or 3 times, but the torque of the motor keeps breaking it. I have an '02 with 290,000 miles.


Mine

Mine,


You have 290k on your truck? Any rebuilds, mods, upgrades? I haven't heard of anybody with more miles than that on a Dmax.

Mine,


You have 290k on your truck? Any rebuilds, mods, upgrades? I haven't heard of anybody with more miles than that on a Dmax.

no, the real question is how many sets of injectors he has put in the truck.

Jim

Mine,


nope not the pipe, thats looks ok,





So no one knows what that is? Only one Dmax and one PS in the world make this noise?


Maybe a trip to the dealer is in order,





Rob

Mine,


You have 290k on your truck? Any rebuilds, mods, upgrades? I haven't heard of anybody with more miles than that on a Dmax.





That is allot of miles, but the most I've heard of is well over 400,000 on an 01. He has a company that hauls cars & trucks back and forth across the country. They keep their trucks running non stop. Unsure of exactly what maintenance issues he had, but it didn't seem that he had any real problems with the truck. It was stock if I remember correctly.

Rob


My truck has no mods. & is in the shop right now waitting for its second pump & 5th set of injectors.And if it didn't spend so much time at the shop I'd have about 340,000miles by now.Good luck with your promblem.





Mine

http://www.dieselplace.com/forum/smileys/Ouch.gif


5th set of injectors? I thought the replacements were supposed to cure the problem?


Dan

Thanks for the hijack





Rob

So, back on topic. We took a roadtrip to Austin last night. About an hour and 20 minutes one way.


Anyway, I noticed when I hit 2500RPM at 80 MPH, that my engine got noticably louder. Sounded "like a diesel engine" if you will. Drop below 2500 RPM at like 79MPH, and the engine quieted right down.


Is that the pilot injection turning off when I go faster?


Just like the noise that was mentioned, mine didn't do it when I cut the cruise control off or took my foot off the accelerator. I guess I need to research a little on this Pilot injection thing.


BTW, this is my first Diesel.

Alright - found out what it is...


http://www.duramaxdiesel.com/01_features/sub05.htm
<LI =disc>The sophistication and technology of the direct injection system components make the Duramax engine capable of employing a process known as "pilot injection."


<LI =disc>Pilot injection involves injecting a small amount of fuel into the cylinder prior to the main injection event. A complex process in the electronic controls selects the optimal time, duration and quantity of pilot injection, coupled with the main injection charges.


<LI =disc>The result — combustion starts on a smaller scale and builds subtly, but rapidly, for reduced noise/knock, less vibration and quieter and smoother warm-ups.
</LI>


Makes sense to me that when it cuts out at 2500RPM, that my engine gets louder, and "sounds more like a diesel" since it becomes a less subtle combustion process, and more like a typical single injection of fuel/air.

Corona said,


Anyway, I noticed when I hit 2500RPM at 80 MPH, that my engine got noticably louder. Sounded "like a diesel engine" if you will. Drop below 2500 RPM at like 79MPH, and the engine quieted right down.





This is what I understand happens when the pilot injection shuts down at 2500 rpm, and I've heard that before, But what I hear is a clatter, (only when the windows are up) when I throttle up, when I get off the pedal its gone, I just wondered if it was normal, or does every engine clatter when on the throttle.





Thanks


Rob

Rob,


So, are you hearing two different distinct sounds then?


1) being the high speed "cack-cack-cack-cack" diesel engine sounds


2) the clatter noise?


Or, is it only the clatter noise at high RPM?

Corona


Its only one sound, Sort of reminds me of gravel in a coffe can, clatter like,


I can't really hear it with the windows down but at any speed when I give it some throttle the "clatter" starts, foot off the pedal and it stops. Its not there at idle only under power.


It even reminds me of when a gas engine runs on when you turn the key off just before it quits,


I dunno, maybe I'm http://www.dieselplace.com/forum/smileys/Wacko.gif





Rob

strange. Only thing I can recommend is taking the service manager on a drive with you and a technician to show them what it is like.


If they say it's normal, have them get a new Diesel off the lot and prove it to you.

04ROB,


Did you ever get any resolution to your problem? I have what sounds like the same thing. Driving on the freeway I hear the rattle. Sounds like a gasser knock. Ease off the pedal a little and it goes away, back on the pedal and there it is again. It is pretty annoying.


It sounds just like when the Pilot injection cuts out at 2500 rpm but I hear it way below 2500. For me its most noticeable around 2000 rpm / 65mph but I can hear it below that. I just had my ECM re-flashed and that seemed to lessen it but its still there.


Dealer showed me a TSB (PI01845A) and says its 'burst rattle'. TSB doesn't say what 'burst rattle' is and dealer can't explain what it is. Posted in the Tech forum to see if anyone knows.


If this is normal I'm o.k. with it but I just need to find out one way or the other.

MMW


Nope, never found out what it is, I've learned to tune it out, Basically its a light rattle noise when the engine is under load (acceleration) and dissapears when crusing or the speed catch's up with the pedal.


Its not pilot injection shutting off, unless the pilot injection shuts off when you hit the pedal, But I've heard the pilot injecton shut down at around 2500 rpm and its different,


I build engines so I am ear tuned for noises, roll up your windows give it some throttle on the highway and see if you can hear it. it then dissapears when the speed catch's up to the throttle position.


Rob

mine does the same thing

Just a theory but as you are increasing speed the computer may not be able to time the pilot injection 100% correctly so there may be some more "diesel chatter" while accelerating? Just a thought. Mine does the same thing.

isnt this all related to the fuel knock at 1800 rpm problem that a lot of are having - mine will rattle and knock like crazy from 1600-1800 rpms and drives me f'n nuts - going in next week to have it fixed

lakingslayer,


I was thingking the same thing that it might be the pilot injection cutting out but i thought it only cut out at 2500 rpm because the revs were too high to be able to time the pilot injection correctly. At 2000 rpm and below it should have no problem keeping up so I don't see why it would cut out.


Anyway, after 2500 when the pilot injection cust out it does sound different than the rattle/knock.


Let us know if you have any luck with the dealer. I took mine in and got nowhere. They said they replaced the egr solenoid and that fixed it. I told them when I picked up the truck that I doubted that was it. The service manager went and got a tsb and showed me that GM referred to it as 'burst rattle' so they are aware of it, too bad no one at the dealer was able to explain exactly what it was. The tsb said to tell teh customer to use a couple of tanks 'f 'good quality name brand fuel' and it would probably go away'. Right.


I'll go back and go for a ride with the diesel tech to make sure he knows what I'm talking about and see what he says. I hate having to talk through service managers.

lakingslayer,


I was thingking the same thing that it might be the pilot injection cutting out but i thought it only cut out at 2500 rpm because the revs were too high to be able to time the pilot injection correctly. At 2000 rpm and below it should have no problem keeping up so I don't see why it would cut out.


I'm not saying it cuts out but maybe it misses the sweet spot when it squirts the fuel in before the main fuel dump into the cylinder on acceleration.

When I accelerate it isn't as loud as it is after the 2500rpm cut out. That is why I thought of this as being a possible cause. I could be totally out in left field here.

Mine did it too before the TTS Tow Tune was installed. Seems to have went away since then.


It's nothing to worry about, IMO. They all do it.


Just wait until you hear the Hurricane Fan of Death, that noise will make you http://www.dieselplace.com/forum/smileys/Dead.gif