howling/Drone sound

[BrassBandit]

Ok so this just started. When the truck is under load and I'm heavy into the throttle I get a howl, and a vibration, it sounds almost harmonic. As soon as I let go of the throttle it stops. I checked my torque on my tires just to be sure I wasn't about to lose one (been there done that). So now what should I start looking at.

1993 f350 idit
Zf5
Dually

 

[Thewespaul]

Look underneath with a flashlight and go over all the exhaust connections around the engine, you likely have a leak that only wails when you have a lot of drive pressure behind the turbo

 

[BrassBandit]

Look underneath with a flashlight and go over all the exhaust connections around the engine, you likely have a leak that only wails when you have a lot of drive pressure behind the turbo

I literally said it sounds like an exhaust leak to my helper ( I'm a welder) just yesterday but didn't want to throw my own guesses out there. I'll check it out Monday when I can get it in a garage.

 

[The_Josh_Bear]

A vibration under load makes me think a ujoint is starting to show its age.

But I also have a situation where in 1st or 2nd gear if I romp hard while towing my engine shifts enough to make some part of my(admittedly loose) exhaust clatter on the firewall. This makes a noise and vibration but no howling.

 

[BrassBandit]

A vibration under load makes me think a ujoint is starting to show its age.

But I also have a situation where in 1st or 2nd gear if I romp hard while towing my engine shifts enough to make some part of my(admittedly loose) exhaust clatter on the firewall. This makes a noise and vibration but no howling.

You can't feel the vibration in the steering just in the floor. if that helps at all

 

[renjaminfrankln]

Exhaust contacting the cab/firewall is my best guess. Look at the pipes going to/from the turbo and see where they could be contacting the cab when the engine is torqued in the mounts.

There isn't much clearance there to start with and when the cab mounts get old and sag, it reduces the clearance even further.

I had this issue with my truck and I would describe it almost exactly as you did. The exhaust/engine vibrations tend to resonate in the cab and cause a "harmonic" due to the direct metal/metal contact.

 

[BrassBandit]

Exhaust contacting the cab/firewall is my best guess. Look at the pipes going to/from the turbo and see where they could be contacting the cab when the engine is torqued in the mounts.

There isn't much clearance there to start with and when the cab mounts get old and sag, it reduces the clearance even further.

I had this issue with my truck and I would describe it almost exactly as you did. The exhaust/engine vibrations tend to resonate in the cab and cause a "harmonic" due to the direct metal/metal contact.

Harmonics is a good way to describe the noise

 

[ttman4]

Not there to hear or feel it but as Josh said, could be U-Joints. Also if you have a carrier bearing ck that too. Could be rear end maybe??? & as Wes & others said could be exhaust leaking or vibrating against something. If you getting vibration under load I'd look for all other stuff

Few yr ago I was helping a friend that had a howl under pull/load. Found carrier bearing wore out. Fixed that & still had howl, sounding like from Tran area. We jacked it up & kept cking things. Finally disconnected driveline & howl stopped. Turned out to be rearend howling.

Also turned out he had busted pass. side motor mount too.

 

[Conky]

sound like gears to me, how's the diff oil?
get your pinky in there

 

[BrassBandit]

Well I think I got it figured out. steady bearing is thrashed. I'll swap it out hopefully this week and report back

 

[BrassBandit]

All fixed up. Did the steady bearing last night and u joints while the drive shaft was out. thanks for all the suggestions