Turbo noise on throttle backoff or trans shift

[DSorenson]

I was wondering if anyone has run into a situation where a rushing or exhaust resonance noise is heard from within the cab coming from the general direction of the turbo when either the throttle is abruptly backed off or when the shifts to a higher gear, particularly when shifting to overdrive while under load? If I had to guess at something it sounds like boost air bleeding off in someway that is creating this strange noise. Could there be a torn hose(s) that I should be looking for?



Thanks!



Don

 

[JEstes]

First off, a few questions: 1. Do you have a boost guage? 2. Do you have any "bombs" (modifications)?



A torn boot usually results in ALOT of smoking, and noise all of the time. There's a chance you are "barking" the turbo, but I'll bet you're just hearing the wastegate opening. That's where the boost guage/bombs questions come in.

 

[Cattletrkr]

Dad's '03 does that. I don't drive it enough to know exactlywhen it does it. It's been doing it for 3 years or so... since he got it and it's not gotten any worse.

Do you have an "open element" air filter?

 

[PBrauer]

Is it definately a new sound or a semi-familiar sound that seems to be getting louder?



Check your exhaust manifold gaskets. Climb up in there as far/close as you can with a small inspection mirror and a flashlight. Look hard for any carbon "stains" around the gaskets. Try to look all the way around each one (deliberately) with the mirror and look especially hard at #6 and #1. Another trick is to use a small digital camera, macro mode, and take extreme close up photo's. I suspect you'll find some leaks.



The sound you're hearing is probably air being sucked into the leaking gasket(s) by the inertia of the turbine. I just went through this. It started as a rushing air sound but progressed to an awful screech when backing out of high boost. I could also hear the rushing air sound following mid-power upshifts but I thought it had something to do with my new intake.



The gaskets are made from three very thin sheets of metal. There isn't any soft material in there. Don't try to find loose pieces... you won't find any. Just look for the signs of gases blowing out. If you find a small leak it's probably OK to simply retorque the studs but if it's been leaking badly or for a long time then there might be too much carbon in/on the sheets to seal it back up.



In the end it was far easier for me to replace my gaskets than I expected it to be. I wouldn't be surprised if a shop familiar with the 5. 9 billed the job for two hours or less. The gaskets aren't all that expensive if you get them from Cummins. Some of the vendors here at TDR also sell them.



If you find leaks, it's nothing to freak out about but it should be addressed reasonably soon. My manifold was fine but others have reported warpage after putting it off for too long. I never lost enough boost to consider that a symptom. Don't let a shop convince you that everything is fine just because your boost seems normal. I was leaking pretty bad but could still make nearly 40psi (mostly stock).

 

[Forrest Nearing]

definately look for cracked/slipped boots. a boost leak can cause what your'e describing due to overspinning the turbo. also verify that your wastegate is operating properly

 

[DSorenson]

1. Do you have a boost guage? No
2. Do you have any "bombs" (modifications)? No

The truck is new to me - purchased it about a month ago - so it could of had modifications that were removed by the dealer.

 

[DSorenson]

Do you have an "open element" air filter? No

Everything is standard OEM, as far as I know...

 

[DSorenson]

Is it definately a new sound or a semi-familiar sound that seems to be getting louder? The sound definitely isn't supposed to be there. I haven't had the truck long enough to know if it's getting worse, but typically when you purchase a vehicle used it was traded in for a reason, and this could be it (or part of "it"). We were driving around up in the mountains (I live in Denver) and the sound was worse at high altitude (9kft), which might make since since the ambient pressure there is a bit lower than here at home.

I will definitely look at the exhaust manifold per your suggestion and report back.

Thanks!
Don

 

[DSorenson]

Everything seems to check out with regard to inspecting the hoses and exhaust manifold gaskets. With a wench I can definitely move the waste gate linkage back and forth, though it seemed a bit sticky when I first moved it (I simply took an appropriately sized open-end wrench placed it on the bellcrank that attaches to the actuator push-rod and gently rotated it back and forth).

I test drove it again today and all seems to be OK, no unexpected sounds. Even with the passenger window down while pulling up a hill along side tall curb to echo the sound back into the cab. You can distinctly here the turbo spool up and down, but no harsh resonating or vibration noise. Yesterday when I noticed the noise we had been driving for nearly 300 miles, has anyone ever had a problem with a waste gate sticking shut?

Don

 

[JVolpe]

Fill out your signature, easier to know what exact truck configuration.



Sounds like turbo bark by the definition of when it happens. A lot of trucks do bark the turbo, but most are modded in some way. A TC/Trans upgrade for an auto seams to be the most common mod that will bark a turbo.



On the 04. 5 and up with the electonic controlled wastegate there have been some posts on the solenoid sticking.



It is not normal on stock trucks and not necessarily good for stock turbos, but I barked my stock turbo a lot with the same circumstances; let off accelerator quickly while excellerating or when TC locks up while hard or WOT.

 

[Forrest Nearing]

Everything seems to check out with regard to inspecting the hoses and exhaust manifold gaskets. With a wench I can definitely move the waste gate linkage back and forth, though it seemed a bit sticky when I first moved it (I simply took an appropriately sized open-end wrench placed it on the bellcrank that attaches to the actuator push-rod and gently rotated it back and forth).



I test drove it again today and all seems to be OK, no unexpected sounds. Even with the passenger window down while pulling up a hill along side tall curb to echo the sound back into the cab. You can distinctly here the turbo spool up and down, but no harsh resonating or vibration noise. Yesterday when I noticed the noise we had been driving for nearly 300 miles, has anyone ever had a problem with a waste gate sticking shut?



Don

if the wastegate diaphraghm is torn/blown, you won't get any wastegate actuation, and the turbine will turn considerably faster

 

[WoodChuck]

Mine started making a noise similar to what you are describing after I changed my exhaust and intake.

 

[AMassaro]

Sounds like regular ole barking the turbo. My opinion is you'll just have to learn to drive around it.

 

[AHughes]

SOUNDS LIKE TURBO HUFFING. WHEN BACKING OFF RAPIDLY I'LL DO THAT. TRY LETTING OFF THE FUEL PEDAL SLOWLY AND SEE IF IT DOES IT? ALSO AS OTHER HAVE INDICATED CHECK YOUR TURBO DUCTING BOOTS FOR TIGHTNESS AND SOME MIGHT HAVE SLIPPED OUT FROM UNDER THE CLAMPS. GET SOME SILICONE BOOTS AND CLAMPS FROM RIP AT SOURCE AUTOMOTIVE IN PORTLAND WEB SITE IS Source Automotive -- Main. AHughes, Sisters, oregon

 

[WoodChuck]

Mine made the noise this morning getting on the freeway going into 4th and lock up without letting up on the throttle pedal,
maybe 20% power.