Odd Flutter Noise???

[GNielsen]

Hello Everyone! I'm a new member and this is my first posting! I have a 2003 3500 DRW HO with the 48RE Auto. I have 17500 miles on it and the only mod so far is a 4" DPP exhaust. I am getting an odd flutter noise that's coming from the passenger side, I'm thinking it has to be either the turbo or air intake but not really sure. It happens between shifts or if I put the pedal to the floor and then let off quick(i. e. mountain driving). I notice it especially when I'm pulling or when I'm heading up the mountains empty. I also hear it every once in a while driving around town too, it's just not as predictable. This is my third diesel and I've never noticed anything like this. Does anyone else get this noise or does anyone know what it could be?



Thanks for any help/advice!

 

[dieselpilot1969]

how about when you stand on it and it goes into overdrive, if so this is normal. it is the air backwashing through the turbo, otherwise known as chuffing. take the silencer ring out this should help!

 

[ttreibel]

There was a great write up in the last issue of the TDR about turbos and backwashing it's worth the read.



Backwashing has been known to break the turbo shaft however I haven't heard of one on an 03 yet. Cummins engineers recommend avoiding the situations that cause this.

 

[rmcnamee]

Is the noise people are talking about kind of like a light to moderate "howl" or "growl" when climbing a hill? Or maybe a "loud" PS pump? If so, mine has done it since day 1. I tried the silencer ring removal trick, which at first seemed to cure the problem, but then I realized it really didn't. How does Cummins say to avoid this condition? I don't try to make it happen, it just does it and I don't really "beat" on the truck.



I think if there is a possibility of breaking the turbo shaft, DC/Cummins should come up with a fix and recall all of the trucks and make the necessary repairs. After all, it's the least they (DC) could do, since I (as well as everyone else who bought a new 3G Ram) spent a lot of money to buy the truck and should get my moneys worth.



What TDR issue covered this topic... I'd like to read up on it a little. BTW, when did the last issue come out... I haven't seen one in the mailbox for quite some time now and I know my annual subscription isn't up yet.



Ryan

 

[GNielsen]

Tom... if you could post the issue number that explains backwashing that would be great... I'd like to get my hands on that issue and do some reading.



Backwashing sounds like my problem! It does occur when I stomp on it as it goes into overdrive, but as I noticed this morning it happens occasionally when just driving normal, accelerating lighlty! I've seen this problem before in other diesels but primarily only after modifying the air intake to be more free flowing without modifying the turbo or turbo housing!



I'm convinced that this occurs way too often on my truck so I'm headed over to my dealer later this morning to see what they say! If it's possible to break the turbo shaft, I'm possitive it won't be long before it happens! I do a lot of mountain driving and I also do a lot of heavy pulling, being an excavating contractor!



I'll let you know what I get out of the dealer! :-{}

 

[rmcnamee]

My questions is, why didn't the 2G 24V Cummins experience this condition.



GNielsen, let us know what happens at the dealer.



Ryan

 

[ttreibel]

Issue 41 the current one. Pages 22-27 Technical Topics "Revisting The Equation: Air + Fuel = Power" by Joe Donnelly



Everything you want to know and more.....



The 2nd Gens also do this the new engines with the common rail are so quiet you can hear it better now

 

[GWDiesel]

Flutter sound

Yes, I have the flutter sound only, loud! I am going to try a

Flowmaster muffler when the heat shield comes in the mail

you have to tilt the muffler to clear the frame,and I dont want

to melt the bed liner,plus 70 gal diesel on top of that. That

flutter sounds like I am trying to boil rice. GWD

 

[KWIKKURT]

Generally it is called "Barking the Turbo"



The engineering term is "Compressor surge or stall". It can occur occasionally with a stock CTD if the conditions are just right. Generally just letting of the throttle smoothly or not completely releasing it while speed shifting will eliminate the conditions that cause Barking. In real simple terms the compressor has more air / boost pressure than the engine will accept and the air flow "Backs up". This is compounded by letting up on the throttle or shifting to a higher gear and/or slowing down the rpm reducing the air flow thru the engine. It is even more common with high performance turbo chargers with larger compressor wheels.



The noise is caused by reversal of the airflow through the compressor. Quickly backing of the throttle or the "Kwik" reduction in engine rpm causes the turbine side wheel of the turbocharger to loose drive energy. The Compressor wheel then slows down. With the impeller decelerating, since it is dynamic rather than a positive displacement air compressor, it cannot maintain the head (high boost pressure) seen in the air intake, Intercooler and the turbo's compressor outlet and the air flow reverses through the compressor of the turbocharger. (Note: The turbo charger's wheels DO NOT Reverse rotation. ) The reversal of the airflow unloads the compressor impeller, shaft and turbine. Once the excess head has been dumped, the compressor pressurizes the intake system again, but if the turbocharger is still decelerating, its speed can fall to a point where it cannot maintain the head it has created, the flow reversal will occur again. This process can repeat itself over and over if the conditions are right. Each time this occurs you will hear a "Whoomp" or "Whoosh" or "Thump".



The repeated loading and unloading of the compressor wheel, Shaft and Turbine wheels can cause cyclic fatigue failures. This is not a good thing for most turbo chargers although their is at least one that will stand up to it.





Kurt.



Note: Much of the above terminology is borrowed from a post I read long ago from someone identified as "Rusty". It was the best explanation I had seen to date.

 

[GNielsen]

rmcnamee, sorry for the delay!



I finally got an answer from the dealer and it's the same old story! The mechanic said that he called DC and they didn't have a fix for what we are talking about. They also said that it wasn't detrimental and that it is just an annoyance!



I'm going to continue to keep an eye on this and I will be interested to see if it gets worse when I add an EDGE Comp once it becomes available!



KWIKKURT... thanks for the detailed explanation!