Heres one for ya! What do you think this noise is?

[mattymac]

I dont really claim to know alot but I feel im not stupid either. Check out this video clip of a 3rd gen dodge climbing a hill, and tell me what you think the noise is when he lets off the throttle. Then look at all the comments down below, mine is in there and I think its pretty easy to figure out which one is mine.





I guess thats what happens to a diesel guy who goes over to a ricer/gasser site all the time!



http://videos.streetfire.net/Comment/0/2DDCBCC0-B2EE-40FD-BB35-269D38E57861.htm

 

[ABossana]

That was an easy one... ... ... it had to be the muffler bearings.



haha j/k... ... ... ... ... ... ... ... . Blow off Valve for sure

 

[cojhl2]

Thats the wastegate and its hard on things to let that happen thats for sure.



If my boss caught me doing that on his 359 I'd be walking down the street talking to myself!!

 

[rbattelle]

I agree with mattmac - it's turbo bark. It has nothing to do with the wastegate.



-Ryan

 

[DWeiler]

Me too,turbo bark,my b1-2 sounded like that before the BD turboguard installed ,when it did bark,usually only one Bark,telling me to smarten -up

 

[rjohnson916]

Yeah it does not have a blow-off or diverter valve. My truck with just a K&N FIPK and the silencer ring still in makes the same sound when you are in snow, and suddenly let of the throttle.





-Ryan

 

[nickleinonen]

yep, bark. . [mine has not done it that bad though ]

 

[cojhl2]

I always thot they were the same. Someone enlighten me!!



Isn't it casued by too high presure in the intake stream without the necessary power required to keep the turbine to hold that pressure,, there fore causing added torque on the shaft.

 

[cojhl2]

OK,, I went to the book and I guess there isn't even a wastgate on these engines. (right?)



Anyway the more I think about it the wastegate allows a bypass of presssure above some value in the intake stream. (Right?)



So, when the power is abrubtly pulled off how couild there be too much pressure?



So I guess that bark as you call it is caused by the turbine seeing too much output pressure for the amount of avail energy to hold that pressure.



Thats what I always thought the noise is but somehow always related that to wastegate apparently incorrectly.



Is this all correct?? Appreciate your responses.



NTL its darn hard on the turbo according to all my professional driving friends and you dont let that happen. You are supposed to back off the fuel more slowly.



Waddya think?

 

[jwilliams3]

No, a releif in the INTAKE side would be a "blow-off valve".



A wastegate is a turbo speed/boost governing device. A wastegate can be set to open at a desired boost pressure and can regulate turbo speed and boost pressure.

The wastegate allows hot exhaust gas to bypass the turbine housing and wheel by dumping it directly into the exhaust pipe (or close to it).

Thus diverting exhaust flow away from the turbine which powers the turbo.

The (internal) wastegate is a trap door that is connected to a small lever that is connected to a rod that is connected to a diaphram that is pressure (boost pressure) activated.



What you hear on the video is turbo barkl. That truck was probably already at max boost with the turbo's wastegate fully open to begin with.

 

[CumminsPower98]

Reading the comments on that video makes me LOL. All those guys calling them selves Diesel techs and they can't even ID that noise, calling it waist gate and BOV. HAHAHAHA

 

[MCummings]

OK,, I went to the book and I guess there isn't even a wastgate on these engines. (right?)

Actually, they do. Since '94 Dodge/Cummins have come with Wastegates. In '04. 5 they went to a electronic style wastegate, and in '07 (with the 6. 7L) they got rid of Wastegates and are using VGT technology.

Anyway the more I think about it the wastegate allows a bypass of presssure above some value in the intake stream. (Right?)



So, when the power is abrubtly pulled off how couild there be too much pressure?

Because the drive pressure is removed to abrubtly and the turbine slows down faster than the motor can consume air.

So I guess that bark as you call it is caused by the turbine seeing too much output pressure for the amount of avail energy to hold that pressure.



Thats what I always thought the noise is but somehow always related that to wastegate apparently incorrectly.

It has to do with the compressor wheel trying to flow more air than the motor can consume.

NTL its darn hard on the turbo according to all my professional driving friends and you dont let that happen. You are supposed to back off the fuel more slowly.

It is hard on the turbo, but with a modded truck, accelerated turbo wear is generally not at the top of teh list for things to worry about.



It is hard on everything (Engine-drivetrain-suspension etc) to lift off power so quickly as to allow turbo bark to happen.







HTH,

Merrick

 

[cojhl2]

Thank you jwilliams3 and mcummins for your answers. I appreciate your time to explain it.



cumminspower98 I never pretended to be a diesel tech! I've driven diesel since the late 1940's starting as a kid. That does not mean I understood everything that is going on.



I dont think I deserve to be laughed at!!!!

 

[CumminsPower98]

No disrespect to anyone who truly didn't/doesn't know, I have no problem with that. I just thought it was funny for those who were claiming to be big Diesel techs and sounding like they knew it all but were dead wrong (talking about the comments on the site the video is on not this site). I sure am no Diesel tech either and lack much knowledge in the area but thanks to these forums I am learning a lot.

 

[cojhl2]

OhHo CumminsPower98,, my apologies for jumping to conclusions regarding your comment. I thought your comments were directly at me as I was the only one that said Wastegate on this forum. I did not realize there were other comments on the other forum.



Thinking this thru (which I obviosly did not on my Wastegate response) one has to conclude as we did here,, its back pressure thru the turbine. I always knew that but somehow equated that to wastegate,, dumass!!



And, you are right,, this forum is a wealth of knowledge. . For sure I know I am not to old to learn.



Thanks Cumminspower98 for your response. .

 

[EMD Diesel Power]

Its turbo bark... also known as compressor stall (for you jet-engine people out there).



Simple physics of high pressure (intake mainifold) flowing to low pressure (back into air intake)... through the stalled compressor turbine. In this case... the air is going backwards through the turbo and out into the airfilter housing.



As mentioned above, its really hard on components and its an easy way to bust a turbo shaft this way... . compressor wheel stalls... so does the exhaust wheel since they are connected via solid shaft. The stalls only last very briefly (less than a quarter-second in most cases). And quite often in a severe case such as the video, there will be multiple stalls in a very short time as the pressure bleeds back and equalizes until the demand for power is back up (more fuel, hotter exhaust gas).



Generally if its done on the road, it usually only barks once...

 

[WyattEarp]

Is the wastegate there for that purpose to relieve that built up pressure when sudden deacceleration occurs?

 

[jwilliams3]

No, the wastegate is there keep turbo speed turbo boost in check.

Also, it releives power robbing back pressure which can also decrease mileage.

 

[MMiller]

Man, my truck must obviously be a misfit, it does not have a BOV or a wastegate, and its made that noise before!!! :-laf I better take it to one of those "diesel techs" and have them work on it for me.



I really enjoyed the comment "ALL turbos have wastegates"..... I'd better go find the 'gate on my trucks.



Michael