Wheel bearing diagnosis

[Musikmann]

Hello Friends,

I have used the search function, found/read some threads on bad wheel bearings, but cannot find how we diagnose they are bad.

Symptoms: I have a mild noise and slight vibration in the front end that is most noticeable when driving in a straight line. It doesn't vary with the speed, but is more noticeable below 40 MPH. This is a 1991 V6 LE with 118,000 original miles.

Solution: I took it to a Toyota dealer who I can trust and they ruled out alignment and wheel bearings. Thinking I might have a bad tire, I took it to Goodyear for my lifetime free rotation/balance (bought the tires there 12,000 miles ago) who test drove it and the guy "thought" I had a bad left front wheel bearing. They have a "free alignment check" which I had done and when up in the air they discovered a split CV joint boot on the right axle.

OF COURSE, they said it needed an alignment and showed me the printout from their nice Hunter machine. I had that done that day, and they ordered the 1/2 axle. I went back, and they r/r the axle. During the axle job the tech discovered one of the old bolts was loose and thought the new axle with properly tightened bolt might fix it. We mutually decided to skip the wheel bearing for now, and they said to bring it back if the noise became worse.

Question: The noise/vibration is still there but seems a little better. What do you guys advise as my next step? I thought a definitive diagnosis of both front wheel bearings is in order, but what about the other parts of the front suspension? Control arms, sway bars, bushings, etc?

Thanks in advance!

[Musikmann]

My apologies. I finally found the following answer by TBayToyotaBoy but my symptoms are not the same and much less severe that the OP reported. In fact all of the wheel bearing threads I found reported much worse symptoms than mine. My best guess at this point is that mine might be going bad but not enough to replace unless/until they get worse.

Bad Wheel Bearing on 91 V6??

Are there any others who care to comment? If so, thanks.

[txturbo]

Bad wheel bearing noise will change with speed. Its a roaring sound kinda like a bowling ball rolling on a bowling lane. Does it only make the noise when moving or does it also make the noise when sitting still with the motor running? Is it manual or automatic tranmission? You could try jacking the front wheels off the ground and running it in drive to see if the noise is still there. It could be a rear wheel bearing.

[Musikmann]

Thanks for the reply.

I just drove the car again and discovered I gave some misleading information earlier. I do not notice it at idle before I start driving. I start to notice it when I get to 15-20 mph and I would describe it as a pulsation that increases in frequency with vehicle speed. To me though, nothing like a rumble of a bowling ball rolling on a lane. I also feel a slight vibration in the steering wheel that corresponds in frequency to the sound. It is an automatic transmission.

I'm sorry that my description is not better. After the Toyota dealer said it was not a bearing that's what made me think it might be a bad tire and that's why I had Goodyear rotate/balance them. The Toyota service manager said the tech used a stethoscope but I doubt he checked all 4 wheels and as far I know the Goodyear guy only came to his conclusion based on a short test drive. He also said it might be the left front bearing.

I don't have a good jack or jack stands but some friends do and I'll act on your suggestion.

I hope this helps.

[txturbo]

It could also be a bad differential bearing inside the transmission. first try jacking both wheels off the ground to make sure its coming from the front. Then jack up one wheel at a time and run it to narrow it down to which side is making the noise.

[Musikmann]

OK, I'll jack it up and see what I find out. I sure hope it's not in the transmission.

[Doctor J]

Do the following test:
Drive at 42..45 mph with o/d on, then swith the o/d off.
If noise changes in tone [howl to whining], it comes from transmission bearings and gears.
on my car I have similar "bent axle" noise that changes to the higher pitch when I switch o/d off and the engine rpm are going up [4to 3 gear ].This noise is most noticeable at light throttle [floating condition];
HOWEVER, if this noise is not RPM sensetive, try to apply brakes lightly; if this changes the noise , remove and inspect front brake pads for cracks and separation [had this problem on my late 79 supra]

[Musikmann]

Doctor J,

Thanks for the advice, I'll try what you suggested. I replaced front rotors/pads with OEM but don't remember how long ago or at what mileage. I can look that up if it seems relevant. Since that time, I replaced rear rotors/pads too, also with OEM.