370s & BHAF

[Reddog1]

I installed both the 370s & BHAF yesterdayOo. . They were the only change.



Now, under hard acceleration, when I let off the go pedal, I get what sounds like a loud rubbing sound on the front passenger side of the truck. It sounds like a metal to metal rubbing of the pads and rotor, but I am not touching the brakes.



I had my tires rotated two weeks ago, and was advised that my front brakes had about 10% wear left.



Any thoughts.





Wayne

 

[Cooker]

You could be barking the turbo but that is not a metal to metal rubbing sound, it is more that a woosh/cough of air. Does it only happen under hard acceleration?

 

[moparguy]

Reddog, I'd pull the hose off the turbo and check the blades for sign of metal to metal contact. Also work the shaft up and down and see if the clearance feels excessive.



How many miles on your truck/turbo?



RJR

 

[Reddog1]

Thanks for the response guys.



It makes the noise when I let off quick after hard acceleration. Does not do it everytime. I did not have the noise when I only had the 3K GSK and #10 plate in.



I noticed today a similar noise (not as loud or long) when the engine died. When I installed the injectors, I lost about 200 RPM at idle. Currently, it idles about 700 RPM. I will address that Monday.



I have about 130000 miles on the truck.



I just put about $700 in the “tune-up” . I am scheduled to have the transmission “serviced” (about $4000) on the 15th. I don’t think my wife would accept a “I need $1200 to service the turbo dear”.



I will check the turbo Monday.



Please explain "barking the turbo".





Wayne

 

[Bhale]

Mine will bark when i let off the pedal real fast after having it to the floor for a few seconds or more (read max boost here). Also, the higher the rpm the eaiser it is to do and the louder the bark. Try to avoid yanking your foot off the pedal.



Brian

 

[Reddog1]

bhale - It could very well be what you are describing. Definately after I let off the pedal real fast after having it to the floor.



I am reluctant to push it now because I have a stock transmission. After I have the transmission "serviced", mabe I can push a little harder.



If it is the turbo bark, is it a serious problem? Other than the foot, what is the cure?



The speed of the boost is amazing. Hits 30 - 32 real quick.





Wayne

 

[lawdog]

When mine did that it freaked me out (started after wastgate froze up and started boosting to 30 psi (unintentional)) I talked to a friend of mine who works in the DIesel Lab at DCX he checked out the truck and discovered the frozen up wastegate and said the nose is the turbo "Cavitating", which happens when you suddenly cut the throttle at high boost. Not that big of a deal, but I try to not lety mine do it,

 

[Deezul1]

Turbo barking is to be avoided unless you want a new turbo. It happens when you let off abruptly under high boost and WILL damage the turbo eventually.

 

[Amianthus]

Barking is a condition that results when the engine has no need for more air (when you let off the throttle), but there is still an air charge on the intake side of the engine. When you hit the throttle for a high fueling run, the turbo is spinning super fast. When you let off the throttle, the engine RPM falls off and the drive pressure falls off the exhaust side of the turbo quite quickly. However, the turbo is still spinning making pressure. The engine has no need for this pressure so it has to go somehwere. Normally, it would go through the engine. But because the drive pressure is gone, the path of least resistance is back out the turbo. So the pressure is forced through the turbo compressor the wrong way, hence the noise you are hearing. This is not a good condition to be in because it super stresses components in the turbocharger and will eventually cause failure. Clear as mud?

 

[Reddog1]

I appreciate the input. I don’t recall seeing this discussed before.



Is this condition relatively rare?



Amianthus – a very understandable reply, thanks.



I hope (I think ) what you guys are describing is what I hear. I have only heard it two or three times. This would be a bad time to tell the wife I need to “service” the turbo.





Wayne

 

[Deezul1]

Barking seems to be more of a problem with higher boost. I dont recall my stocker ever barking but that was a long time ago too. Prolly after 25lbs boost or so it could be more of a problem.