2nd Gen Non-Engine/Transmission My truck sounds like a helicopter

[Qualey]

Last friday we replaced the turbo downpipe with a 4" unit and removed the resonator. All this flows into a BD muffler and tailsection (4" pipe/5"tip). At exactly 2000 rpms (4:10 gears) the engine emits a pulsating sound that sounds exactly like the blades of a chopper. Any higher or lower and its gone. I thought maybe my exhaust manifold bolts were loose, as this is a reoccuring problem on my 99 model, but they are fine. If there is anything I can do to get rid of the noise without putting the resonator back in, I would like to do so, but otherwise I don't mind too bad. I assume its just the result of changing the airflow characteristics and want to be sure its nothing harmful to the truck. Silencer ring is still in the turbo.



Matt

 

[Ron Bissett]

You can try adding a 1' x1"x1" angle banding , clamping welding or other methods along the pipe as others have done to stop the vibrating of the pipe that caused the noise. some use other size than above test to find what will work before any welding is done clamps can be removed along with bands . Hope this helps ,Ron in Louisville KY.

 

[Peterbilt379CJ]

What you might be hearing is the waste gate blowing off.

is this happening just going down the road at 2000rpm or under a load at20000rpm?

 

[Qualey]

Peterbilt379CJ



It happens cruising unloaded in all gears, but is much more pronounced when loaded.



thanks for the help



Matt

 

[Peterbilt379CJ]

you might be hearing your wastegate blow off. Under a heavy load mine makes a huffing noise.



my 600hp cat in my peterbilt now when that wastegate blows off you should hear that thing. sounds like a hole in the side of the motor.



or yourwastegate might be malfunctioninjg

 

[monkfarm]

whirring noise

I have a whirring noise when you get right up to the exhaust pipe only when I have the jacobs brake on. But according to your signature, you don't have one (an exhaust brake).