Drivetrain noise on deceleration.

[Lapper]

Hi folks,

I just purchased a 1972 K20 4x4 4 speed fleetside longbox the other day, and am "enjoying" the process of importing it into Canada. I'll post my import experience once it is complete in another thread.

The vehicle made the cross-state trip across Washington, but makes a kind of howling sound when decelerating. Imagine someone saying "WHOOOoooo" and you have the idea. Now I am left with the task of diagnosing said sound. When I push in the clutch, the noise goes away, so I guess that rules out the engine and front axle. That leaves the transmission, transfer case and rear axle as possible suspects. It is louder at higher speeds.

Any troubleshooting tips would be greatly appreciated.

Thanks.

[Voodooracer]

Without being there I will throw my 2 cents in and say maybe being a 4 speed and 4x4 sounds like a low gear in the rearend. My truck would roar on deacceleration until I shifted into N at the traps.

[jamon8]

pinion bearing

[st1x10]

Rearend bearing. What speeds does it happen? Does turning the wheel effect it? Almost positive it will be in the rear though.

[bryanw1968]

I'm going to have to go with rear end on this one. Check to see if the yoke bolt holding the crush bearing in place has come loose.

Also, if the rear end ring and pinion gears are not set up correctly it will howl.

Good luck,
B

[Lapper]

Thanks for replies!

I was planning on raising the gearing in the front and rear anyway, for mileage purposes, but now it sounds like I can kill two birds with one stone. I'm relieved that the cause isn't likely to be transmission.