Tracking down an engine sound
Towed a travel trailer for the first time last week and noticed a new sound that I've probably dismissed before..
When going between 70-75mph under load the truck gives a groan / droan sound that resonates through the cab.. Go above or below this and it's gone. Not sure how else to describe it.. If I let off the pedal the sound goes away immediately.. It happens in 5th and 6th gear too, so it's not directly related to RPM. Now that I know what to listen for, it does exist when not towing too at the exact same speeds.
Rev'ing the engine to the same RPM's in other gears at different speeds doesn't give this result. It definitely sounds like it's in the engine bay/tranny area as it resonates through the cab. So I don't think it would be a differential or transfer case?
Could this possibly be the torque convertor when it's locked out? I'm not sure how to tell when the TC is even locked out to be honest..
Thanks in advance!
At first I was wondering if it's something turbo related, but it happens whether psi is near 20 and also when it's at 10ish.. so that's where I'm thinking it might be transmission area..
Will try to see if I can record it.. will be hard since I'm not towing to have the sound happen for an extended period of time..
Thanks!
Always has been that way.
I have a farm tractor that does the same thing, at the right load.
I notice them both doing it every time I hear it, but pay no attention to it, I'm convinced it's normal.
I should add, I have hearing aids and it's the type of low tone sound I can hear easily, with or with out
the aids, when others don't hear it.








