perspicat1
New member
I have a 4WD 4Runner with 160K miles. Ever since about 40K miles, it's been making a high-pitched noise. Here are some details about the noise:
* The noise seems to come from beneath the truck, possibly the transaxle area, or from the right front or rear wheel. It's difficult to localize.
* The noise only comes on when the car is moving at about 30 MPH or faster. Sometimes, the noise can only be heard when the car is coasting, at other times it can be heard continuously.
* However, the noise doesn't come on all the time. Sometimes, the car can go for days or weeks without the noise, and sometimes, the noise comes up right away. The weird thing is, sometimes, the noise would not be heard for a while. Then I would stop at a red light, and when the light turns green, the noise comes up when I start driving! There doesn't seem to be any rhyme or reason.
* The noise can be soft, like a bird chirping, or it can be howling very loud. Again, no rhyme or reason.
* External temperature or humidity doesn't seem to be a factor. The noise can come and go whenever it feels.
At first, I was very concerned about the noise. But no one has been able to diagnose it. I am thinking that if it's caused by something being worn out, then surely whatever that thing is would have been long destroyed by now, after more than 100K miles since the noise first appeared. Yet the car is rock solid on the road, has normal acceleration and cornering, no sign of anything loose or about to come apart.
Has anyone come across anything like this? Any idea what is bothering my 4Runner? (Why can't cars speak English?!) I have a feeling that it has to do with the 4WD system. But what? Oil levels seem OK. But every so often, when I disengage the 4WD system, it takes a few tries before the system disengages.
Any suggestion? Thanks in advance!
* The noise seems to come from beneath the truck, possibly the transaxle area, or from the right front or rear wheel. It's difficult to localize.
* The noise only comes on when the car is moving at about 30 MPH or faster. Sometimes, the noise can only be heard when the car is coasting, at other times it can be heard continuously.
* However, the noise doesn't come on all the time. Sometimes, the car can go for days or weeks without the noise, and sometimes, the noise comes up right away. The weird thing is, sometimes, the noise would not be heard for a while. Then I would stop at a red light, and when the light turns green, the noise comes up when I start driving! There doesn't seem to be any rhyme or reason.
* The noise can be soft, like a bird chirping, or it can be howling very loud. Again, no rhyme or reason.
* External temperature or humidity doesn't seem to be a factor. The noise can come and go whenever it feels.
At first, I was very concerned about the noise. But no one has been able to diagnose it. I am thinking that if it's caused by something being worn out, then surely whatever that thing is would have been long destroyed by now, after more than 100K miles since the noise first appeared. Yet the car is rock solid on the road, has normal acceleration and cornering, no sign of anything loose or about to come apart.
Has anyone come across anything like this? Any idea what is bothering my 4Runner? (Why can't cars speak English?!) I have a feeling that it has to do with the 4WD system. But what? Oil levels seem OK. But every so often, when I disengage the 4WD system, it takes a few tries before the system disengages.
Any suggestion? Thanks in advance!