Diesel World


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I have a 2007 Chevy 2500HD that is pro­duc­ing a drone/vi­bra­tion that can be heard and felt. All this seems to worsen at free­way speeds. I have in­stalled new mo­tor mounts and a trans­mis­sion mount with no change. It sounds like a diesel with a straight pipe on it. This truck has ac­cu­mu­lated 50,000 miles and is all stock.

I checked the ex­haust sys­tem and found no part of it touch­ing a chas­sis or pow­er­train com­po­nent. I can feel the vi­bra­tion in the front tires, the ex­haust sys­tem and the body, but when I touch the frame rail it’s a very light vi­bra­tion. The drone seems to be com­ing from high on the en­gine and is more pro­nounced at the top of the shift points. I can also feel the vi­bra­tion in the air fil­ter box. Has any­one ex­pe­ri­enced any­thing like this?

Mike Mog Via Email

Du­ra­max’s have drone is­sues with many after­mar­ket ex­hausts. The noise usu­ally hap­pens at a cer­tain fixed RPM and the fix of­ten means a new ex­haust sys­tem must be in­stalled. How­ever, if you’re cer­tain it’s not the ex­haust, have you elim­i­nated the front wheel bear­ings as a pos­si­ble cause of the dron­ing sound?

Through the years that I’ve owned diesel pick­ups I’ve had two that nearly drove me to the brink due to a hard-to-di­ag­nose dron­ing sound. The drone seemed to be re­lated to en­gine speed, which caused me to be­lieve the an­noy­ance was re­lated to the en­gine. In both cases, a bad front wheel bear­ing was even­tu­ally dis­cov­ered to be the root cause of the an­noy­ing sound.

What fi­nally shed some light on the wheel bear­ing is­sue in one case was that I no­ticed the sound would nearly dis­ap­pear when in a grad­ual right hand curve at free­way speeds. The right side of the truck would un­load ever so slightly in the turn, tak­ing pres­sure off the right-side wheel bear­ing. The right front wheel bear­ing had ap­par­ently been af­fected by an 18-inchdeep wa­ter cross­ing I had driven in a few months be­fore. Wa­ter must have seeped into the wheel bear­ing assem­bly and pit­ted the sur­faces. Why the sounds seemed to be re­lated to en­gine speed re­mains a

mys­tery, though some have sug­gested that the noise pro­duced by the bad bear­ing was res­onat­ing with the en­gine and cab struc­ture, which pro­duced har­mon­ics at var­i­ous speeds. Sounds com­pli­cated, but I do know the an­noy­ing sounds com­pletely dis­ap­peared after chang­ing the pit­ted wheel bear­ing assem­bly.

I re­placed the front wheel bear­ing hub as­sem­blies in my 2001 GMC a cou­ple of years ago for largely the same rea­son.

The bear­ing in one hub assem­bly was bad enough to cre­ate a “fairy dust” of steel par­ti­cles that ac­cu­mu­lated on the A-arm and brake ro­tor. Also, there was move­ment in the front wheel/tire when it was lifted off the ground. The source of the drone was ob­vi­ous at that point. Gen­uine OE re­place­ment Timken brand hub bear­ing as­sem­blies were avail­able from Ama­zon with free ship­ping for about $140 each at that time.

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