Just recently, I've begun to notice a humming sound during deceleration in my 05 V8 4x4. It most resembles the kind of resistant sound that occurs when you shift down in a manual to slow the vehicle. If I just roll around the neighborhood with the windows down, I don't hear any kind of noises and I experience no vibrations and the vehicle seems to be shifting smoothly. It has just over 100k on it and the oil has been regularly changed. Any ideas?
Humming sound when coasting-decelerating (05 V8 4x4)
- Thread starter BzJeep
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When I got my 4runner, I drove it off the lot and had to drive back to them the following week because of a very much louder noise like this. It was my differential (I have only 2wd :[ so the back one, naturally), specifically the bearings in it. They needed replacement... So I went back to the dealer and they fortunately did it for free, since I had bought the car so recently. Sure was a pain to wait for it though, with only an occasional backup car..
I'm not saying for sure it's your differential, but it's likely. Try just replacing the dif oil first and drive around with it for a few (around 100) miles; that's what we tried first at the dealer's mechanic.
Unfortunately, I haven't narrowed down the issue yet. When I took the vehicle in for S/E at the Toyota dealer, I had one of the techs drive it around briefly so I could show him the noise and he was convinced it was the tires... which I just had replaced and since it was making the same sound before I replaced the tires, I know it's definitely not the tires.
Once I have some money, I will try replacing the differential fluid.
Once I have some money, I will try replacing the differential fluid.
nevada
Senior Member
likely a differential bearing. usually its the rear.
shouldn't be too hard to locate with a stethoscope. or even a long screwdriver.
get it up on jackstands and have someone work the throttle.
run it in gear until you can hear the sound.
then using place the handle of the screwdriver to your ear, and carefully place it on different spots on the rearend until you hear it, at its loudest.
you will be able to hear it everywhere, so check different locations that line up with the different bearings.
BUT...its doesn't really matter WHICH specific bearing it is, so long as you can determine the general area. front diff, rear diff etc.
you'll change all the differential bearings when you have it fixed.
shouldn't be too hard to locate with a stethoscope. or even a long screwdriver.
get it up on jackstands and have someone work the throttle.
run it in gear until you can hear the sound.
then using place the handle of the screwdriver to your ear, and carefully place it on different spots on the rearend until you hear it, at its loudest.
you will be able to hear it everywhere, so check different locations that line up with the different bearings.
BUT...its doesn't really matter WHICH specific bearing it is, so long as you can determine the general area. front diff, rear diff etc.
you'll change all the differential bearings when you have it fixed.
nevada
Senior Member
im not sure what you mean by the whole thing? are you talking about the entire rear axle?
if its the differential, as I suspect, it has to come out.
pulling the 3rd, and replacing the bearings would likely be cheaper than replacing the entire axle.
BUT, I have seen some rear axles go for pretty cheap, and the labor wouldn't be too bad. you could probably id it yourself.
the only problem with that, you have no idea what condition the bearings/gears/differential are in with the used unit.
Toyota 3rds are some of the easiest to replace bearings and set up. having your rebuilt shouldn't be too expensive.
Excuse me for being a bit vague!
I was questioning as to whether replacing the bearings would require the same amount of labor as replacing the entire differential itself.
Also, I am pretty confident that the noise is coming from the front-end rather than the rear-end at this point, which concerns me a bit more as it's an independent setup which I am not at all familiar with coming from Jeep 4x4s.
Either way, when I have some time, perhaps over the holidays, I will try out what you suggested to see if I can pinpoint the noise.
Thanks again.
I was questioning as to whether replacing the bearings would require the same amount of labor as replacing the entire differential itself.
Also, I am pretty confident that the noise is coming from the front-end rather than the rear-end at this point, which concerns me a bit more as it's an independent setup which I am not at all familiar with coming from Jeep 4x4s.
Either way, when I have some time, perhaps over the holidays, I will try out what you suggested to see if I can pinpoint the noise.
Thanks again.
