I have noticed this humming noise coming from what appears to be the front end - the type of noise, if you have been around cars as long as I have, easily attributable to either cupped tires or marginal wheel bearings.- I have lived with it for a while but it finally did became annoying.

- I balanced all tires and rotated them. The tires have probably about 4K miles on them and appear to be wearing out just fine - no cupping
- Even though there was no shimmy on the front wheels whatsoever, I did replace both front hubs with new units.
- Brakes are fairly new and are in great shape - I am running akebono pads
- Rear bearings have been replaced a while back (20 - 30K miles ago) and I am not suspecting them (for now)

This exercise made absolutely no improvement whatsoever.

The noise is drivetrain related - when accelerating, you do not seem to notice it. When you cruise at about 50mph, you can hear it. When you slow down to a stop, even w/o braking the noise is definitely pronounced. To eliminate engine noise, while cruising, I put the gear box in neutral to cut down the RPMs and the noise tracked the vehicle movement/speed.

One thing I did not check was the driveshaft - that's next on my list to check

Is there anything else that I am missing?

Thanks.

 

Are the tyres Jo NoName or a well-established make ? I had a terrible droning noise once on a Rover 75, and it was the Wanli tyres. The worst part was they seemed to be everlasting, but eventually I got rid even though they had plenty of tread left.

 

While you say the noise is at the front, it wouldn't hurt to inspect the differential to make sure all is good bearing wise. If nothing else it would cross another possible source off the list and add a little more piece of mind.

 

I am suspecting that the jurid (donut) flexible couplers at the ends of the driveshaft and/or the center bearing is causing this droning noise - I have not been driving the car very much but it is definitely getting worse. I know JEPC shows that the whole driveshaft would need to be replaced but my search indicates that some members may have done the replacement of the couples and the center driveshaft bearings?

What I cannot seem to find are the part numbers and a source for these couplers and driveshaft bearing. I would appreciate any relevant information/links as my search is not showing anything actionable.

Thanks!

 

Hi Lagonia,

Just to circle back to your original suspicions, don't rule out a front wheel bearing. In my experience, you can't test these integral hub bearings as you could on older Jags, by raising the car, grabbing a tire at 12:00 and 6:00 and trying to sense any movement in the bearing. You won't feel any. You also won't hear any unusual noises or sense any grit or resistance when you spin the tire. To test these bearings, you have to completely remove all mass loading. That means the wheel, brake caliper and brake rotor. And even then, you may have to do this on both sides to be able to tell that the bearing on one side is a little less smooth than the one on the other side.

I have had to go through this on several X350s. The good news is that excellent quality hubs are available from Detroit Axle for around $50 each or $85 for a pair, with free shipping. See their eBay listings.

Cheers,

Don

 

I know rear wheel bearings are a low failure rate,but that is exactly what I had in another car. I first noticed after flushing the differential with Mobil one lube. Thought it damaged a bearing. Knew it was rear. Fete about three rear flushes with OEM lube a friend listened as I drove by. He said definitely was rear heel bearing.
Have someone listen as you drive by. And take Don’s advice on the Detroit Axle hubs if needed. They are unbelievable for 85.00. Even has new speed sensors.

 

Thank you guys! Great minds think alike! That is the first thing I replaced (I mention this in my introductory post) and made zero difference- absolutely none. My plan is to do a thorough inspection this weekend but not sure what I will find out. I'd rather be prepared to just replace them - shotgunning, I know, but hey, the car has 157K miles on it. I've had bearings and u-joints fail on other cars at about 100K miles.

 

Be prepared for your old hubs to be seized in the vertical links due to galvanic corrosion between the steel hub and aluminum link. It can help to apply penetrating oil around the back side of the hub for a few days before you do the job. And when you install the new hubs, apply anti-seize compound to the body of the hub and bore in the link (ideally aluminum-based anti-seize (the silver-colored stuff), but copper-based works too).

Cheers,

Don

 

Thanks Don.

The front wheel hubs have already been replaced before starting this thread. Hubs are not the issue. I suspect my write-up may not have been clear enough.

Currently suspecting the jurid (donuts) attachments to the drive shaft ends or the center bearing.

Rear wheel bearings were replaced about 30K miles ago which, at that time, solved a grinding issue when veering to the left.