Recently I've noticed a dull hum coming from the tranny? or rear end? It almost sounds like the new tire hum, or it being stuck in four high. Tires have 8 thoushand miles on them, and I don't think it is stuck in four wheel drive. It does it at all speeds. The pitch seems to get higher the faster I go. When driving on the highway at 65, if I put it in neutral, the sound isn't as loud, but as soon as I put it in gear and give it gas it becomes loud again. New tranny fluid 300 miles ago and new rear differental fluid 3000 miles ago. Any Ideas?
97 F150 Lariat 4x4
Tritan 4.6, Auto, 132K
White Super Cab
K&N Filter w/modified air box
265 70R 17's Open Country
Pioneer DEH-7600 (sweet)
4 - 3way 220w Pioneer 5 x 7's
When you changed the fluid, did you make sure to use the proper weight of synthetic oil? Also, have you checked the level recently? I know they don't put gaskets on some of the rear ends, and use silicone-- but if you don't let it cure enough, it will leak.
I'm thinking either rear end or wheel bearing, if it makes noise both in neutral and in gear.
Naturally, I don't claim to be a diagnostic guru, but my experience this fall showed me the humming can be a wheel bearing. The speed related humming worsened gradually at first. Then seemed to get worse by the week.
At the end i had the passenger side 4x4 hub assembly replaced. The resulting quiet was eerie at first.
You may be able to hear the front bearings while turning. They usually change pitch, or loudness when turning one way vs the other. Also, you may be able to feel the looseness/slop when the wheel is jacked up off the ground, and you rock the wheel back and forth. Turning it may also reveal some noise.
The bearings are not serviceable. You have to buy the hub/bearing assembly as a unit. I think I paid around $200-$270 at my Ford dealer. I don't recall the exact price. Not too hard to R&R. You will need a 36mm socket for the axle nut.
Hopefully, your rotors aren't frozen on to the hub. If they are, you will need a gas torch to heat it up. Heat only around the hub, not on the rotor surface. If you don't have heat, you'll likely have to break the rotor. Get a big hammer, like a 3 lb'er, and hit the outside of the rotor surface. HARD. A couple or 3 big hits should break the rotor along the top of the hat area. Don't even waste your time trying to tap the rotor loose form behind. If it's loose, you'll know it. If not, you'll be also investing in a new rotor.
Check the rear end my truck did the ame thing and I ended up replacing the pinion and carrier bearings $225.00 at NAPPA as for the rotors there junk,made in Mexico, replace them with the good ones made in the good old USA did that over the weekend along with the front wheel bearings $167.00 at the same store..........
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