Buzball

Hello guys

Been having this problem for a while now it sounds like a wheel bearing and the noise is between 30-60mph and its really obvious

Wheel bearings are fine so put it down to front diff

Changed the front axel complete With a used unit with all hubs shafts and diff etc

Sounds exactly the same, What the heck could it be

Regards

JPXJMOAB

How's the fluid level?

Turbo X_J

Rear axle?

Buzball

Fluid fine noise coming from the front

Cherryokee

Hey Buzball,

Noises can be annoying and chasing-down source(s) can be a real pain. Like with any other vehicle problem, the devil is in the detail. If you want help from the experience-pool then it helps to reveal things like year, model, tires, power- and drive-train.

Despite all that, there are a few things to consider such-as "feel" and the load conditions under which the humming noise becomes noticeable. I had a '96 Ford that hummed but the humming came under part-throttle conditions and at a broader range of speeds. At first I thought it was a wheel, tire or drive-line issue but there was no corresponding "feel" other than a mild power-loss. In that case it turned out to be one of those air-intake resonators in the ductwork, after the air filter and leading to the throttle-body.

When cool it seemed to hum at a higher pitch but the tone would change as air and/or operating temperatures increased, becoming more like a low howl. I was a happy camper when I found the defective intake duct resonator by accident as I throttled the engine with no air filter (for a minute).

Now this is only one small example of how one assumption can mislead your diagnosis. The bottom-line is KISS - Keep It Stupid Simple. Don't be too quick to delve into major mechanical over nuisances like this. You may find something as silly as windage at 30-60mph is causing a loose flap at the corner of the weather blanket to vibrate and hum (like a gazoo), a plastic shroud in the engine compartment is not secured or, like in my Ford, an air intake resonator is failing (if your model has one).

Sorry for the long story but sometimes a dialog can spur the imagination, ya' know?

93_xjcherokee

Stop looking. Its the troll that lives in the back. I heard those things hum sometimes

dave1123

What type of tires do you have? Very often they humm at certain speeds.

I had a friend with a 69 Barracuda that had a loud whistle at 60 mph. Come to find out the front doors had a design fault where air flow made it act like an organ pipe! The factory cured it by installing a rubber flap in the door jamb to disrupt the air flow.

Buzball

Thanks

Can you tell me the correct oil for the front diff please?

JPXJMOAB

Run 80/90 up front with an open diff

dave1123

Ya know? I think I'm going to add this to my tagline;

"Tell us what you've got so we can tell you what you need!" MODEL-YEAR-ENGINE SIZE-T/CASE-LOCATION PLEASE!!!!!

93_xjcherokee

It should be a requirement to post a new thread. Kinda like on craigslist

dave1123

On the axle lube. I changed my rear axle bearings and went to 75W-140 Synthetic. I bought too much so I went to my dealer's service dept and asked if I could use it in the front diff as well. He said "Why not? It's good at low temps and has a friction modifier in it as well."

So that's what I'm running in my front diff and I actually think it's helped my fuel mileage.

SteveMongr

If you suspect a bearing in differential, pinion, transfer case, or wheels, an infra-red temperature gun can help diagnose it. Along with many other diagnostic uses.

Bugout4x4

Lol...Fluid Dynamics under operating conditions are not always investigated like they should be. I remember when Alcoa came out with the first Aluminum Wheels for big Rigs. They turned out to be shaped just right to create a vacuum at about 65 MPH and suck the little moon center hubcap right out of them! It took a while to figure what was happening to all the missing hubcaps, lol


I also remember when all the Chrysler Cop Cars had a very distinct loud whistle as they went by. Something to do with how the grill was made.

mtoskippy

Used the infra red thermo trick all over the wheel, diff and suspension. Puts the mind at ease.

As far as the hum. Could be the CV on the drive shaft? what's your caster? Front drive shaft may be in a bind.

I don't know if you all have heard of "chassis ears" but a friend of mine has a set and they are great for locating noises. Google them.