Matt S.

2014 GL450

When driving above about 70mph I hear and feel a faint rhythmic sound like a wom wom wom wom. Lower speeds I don't hear it at all. Speeding up from 70, it gets faster and stronger. It also may be more pronounced/stronger when steering left. Car rides fine. I'm wondering if this is a symptom of a bearing or hub or something else. I've checked for play by jacking it up and trying to wiggle the wheels in all directions. The problem has remained after a break job, 4 sway bar links, and set of tires. Long highway rides get very annoying.

Thank you

vesiadog

How many miles? Does the sound change when you slow down? Turning right or left?
Read up on wheel bearing noise..

acetaylor

Are all your windows closed including the sun roof and rear wing windows?

Matt S.

Yes.

vesiadog

I have changed 3 pairs of bearing in 164’s.
Front bearings are easier to troubleshoot than rears.
slowly swerving left and right while you are heading the noise .. it will change pitch and come and go.
How many miles on the car and are the bearings original?

Matt S.

75,000 miles and I believe they are original.

vesiadog

75k is definitely early for bearings to go out BUT I just changed a front pair on a GL550-X-164 chassis with 77k miles on it.

AKSwift

Just changed out a couple of wheel bearings at 85k. And one probably needed changing a few thousand earlier.

L&N Caravan

Some approaches that may help isolating the root cause:

- inflate tires to 48 psi on all tires
- find a roadway that has been paved smooth and without bumps, holes, turns. This eliminates sprung/ sprung body weight harmonics.
- starting at 40mph & stepping through to 80mph in 10mph increments, do the following:
- on flat, calm, and smooth road surface, move transmission into neutral (won’t hurt anything) while at desired speed increment and turn wheel left and right through gentle turns (aggressive turning of the wheel provides too many dynamic forces for isolating rhythmic vibration & noise).
- shifter can be moved back into drive without issue while moving (wait 2 seconds after shifting back into drive while fluid repressurizes within converter before depressing gas pedal) to obtain next speed increment target.
While at speed and in neutral, experiment with steering wheel input to isolate and then maximize noise. You will find it occurs mostly or all on one side, or equally on both. The front wheel bearings are made well and oversized.
When isolated, the rhythmic noise will start to reach a resonate frequency and may turn to a deep growl or grumble. You will know when you hear it.
Feel the vibration in the steering wheel and your seat to distinguish front from back bearings. The turns with accompanying noise will indicate left from right side.

Hope this helps and let us know what is learned.

Note: worn front lower a frame bushings may also contribute to a frequency resonance b/c of system dynamics. Check these as well in addition to wheel bearing. Salted roads, aggressive driving, or lots of off roading will exacerbate bushing wear/breakdown.

Note: most of the dynamic forces, hence bearing wear occurs in front b/c of weight distribution and body roll angle inputs. Rear wheels mostly just along for ride.
Pulling heavy trailers especially 2 wheeled only trailers may offset these guidelines a bit and skew bearing/bushing wear to the rear.