Odd intermittent howl from shifter area under boost. Links to video clips within.

Hello again. I hope everyone is well. 2005 VNL Cummins ISX Eaton Fuller 13 speed. Had my mechanic change my shifter bushing as the OEM bushing was shot with a ton of play a few weeks ago. After it was changed I noticed this howl very low volume once in a while but didn't think much of it. It shifts very well with no odd shakes, vibrations or shifting from normal. Recently this noise has become louder and it comes and goes. It really happens in low range but does happen in high range when pulling. It only happens when under boost like pulling through the gears. If you keep the rpms low you don't hear it. It was real loud one night recently pulling Monteagle westbound in 12th with a 10,000 pound load. It comes right up from the shifter location. My mechanic says there are no moving parts under there but I know what I hear. He checked fluid levels and everything seems fine under the truck. He thinks it may be an output shaft worn. He did cut the air lines to the shifter when doing the bushing change and connected them with fittings. Perhaps it is an air leak under there? Has anyone ever experienced this? Any ideas of what it may be? Thanks.

https://youtu.be/WdC68CaCyzU

https://youtu.be/j7XSWb_Bolo

 

Ok will do. I believe the valve was changed just a couple years ago but I'll have it checked out also. Will have fluid checked again. On today's trip the noise was random again and really seemed like it was perhaps coming from right under the shift handle. Like l said l only hear it when accelerating and it is really loud. Thanks for the suggestions, any others?

 

Thanks but l am pretty sure it isn't road noise. You can hear in the videos it is almost a screeching scream once again only under boost.

Fluid levels are full. Looks like tailshaft bearing on the back of transmission is worn and loose with play. Could that be causing this noise? Thanks!

 

Will do. Actually just had EGR Cooler and valve changed a couple months ago when the oil cooler failed. Thanks will check.