2002 transaxle noise diagnosis

2002 transaxle noise question/diagnosis

My 2002 Prius needed tires about 10,000 miles ago and I knew that. The rear ones were kind of scalloped and started making a wierd hum and I replaced em and rotated front to back. Hum went away.

Now I have fairly new tires on the front, and the ones in back aren't new but aren't bad.

There is a hum in the front that just didn't seem like road noise.

I replaced the old trans fluid with Toyota ATF WS fluid, cleaned the pan etc. The old fluid wasn't too bad looking and there was not all that much sludge. I bought this Prius at 180,000 and it is currently at 216,000. It had been very well maintained but I know enough to be aggressive with trans fluid changing.

The hum is still there, seems to be in front, but get this: -at highway speed, the hum is certainly noticeable, but changes when I swerve a little or go around a curve. This would indicate to me either a tire, or maybe a wheel bearing, maaayyyybe a halfshaft (don't even know if my Prius has halfshafts, <G>), but if the transaxle motor windings (?) are humming prior to failure, the hum seems unlikely to react this way to curves and gentle swerves.

The only engine code is the cat converter, and I have thought about just cutting the cat convertor out and replacing it with a straight pipe to the muffler. But that is a whole 'nuther thread!

Any thoughts?

-Joe

 

I can't decide if I should worry or not. Is there anything else I can do? I suppose I could put new tires on again and see if it goes away. I really hope my transaxle lasts forever but I know it's just a mechanical device so after 216,000 miles I shouldn't be surprised...

 

Thanks Bob,

I am very comfortable measuring voltage. I have done it before with needles through the insulation then a little silicone over the hole when I'm done. But I don't know where these sensors are on the transaxle, or what the normal voltage is. I will look for info about that.

I would feel a whole lot better to know that the temps were normal or at least within limits.

Thanks, Joe

 

I looked at both cv boots on the wheels, but not the inside ones. In my experience, the inner boots last soooo much longer than the outer ones, and when the outer boots fail, the usual response is to replace the entire half-shaft.

Wheel bearings are on the short list, but after an hour or so at highway speeds, all 4 wheel hubs feel the same temperature to my hand. I know, an inaccurate cowboy test for wheel bearings, but I have used that cowboy test before with good results.

Next: lift it up and give those halfshafts a good shake. Then find an empty parkinglot and give them the hard turn test and see if I feel anything wacky.

And I am still planning to check the transaxle temps as soon as I can find the info. And if I can't find any info, I will poke around and just guess which sensors they are, and measure the warmed-up voltage from them. Even if I don't know the normal reading, if one is way higher than the other, why, that would be a bad sign, no?

You guys are the best!

 

wow- the price for halfshafts from O'reilly's is around $80 or so after the core return.

I am wondering if it is a wheel bearing instead. How can I tell which noise is which?

 

ok, I replace everything from the antenna down, and see if the noise goes away.

Any OTHER ideas?

 

I think it is a wheel bearing, although I have NEVER had a wheel bearing do this, and I have been driving the s*** out of frontwheel drive cars for years. CV joints, yes; bearings, no.

And every cv problem has been easily confirmable with a tight circle in a parking lot. This odd hum with my Prius does absolutely nothing different with that parkinglot test, which gives me the idea that the CV joints might be (probably are) fine.

I am considering buying a new bearing/hub assembly for the side I suspect (drivers side) and then just a bearing for the other side, and remove/re-press it into the old hub assembly from the driver's side. That way I can replace the driver's side quick and easy, and swap bearings at my leisure so I'll be ready to do the same trick on the passenger side.

I guess I will check back here again in a few days and see if this still sounds like an OK idea.

-Thanks in advance,

-You're welcome, Mister "Only Reader",

-Joe

 

Hmmm, it doesn't seem to vary as much with braking as it does with swerving.

For example, if I am going 35-40mph and make a pronounced turn the the right, say, around a highway cloverleaf, thie sound is very pronounced and seems to increase with loading the left front wheel. The same move (but to the left) seems to reduce the sound.

I will have to experiment some with the hard braking question- but I haven't noticed any and I think I would have.

-Joe

 

post script:

I pulled the brake off and cut little lines around the axlenut dent, using a small cutoff wheel on a dremel tool. Then driving a filed-down screwdriver in there popped it right out and the nut came off easily with no damage whatsoever. I suppose I could have re-used it but a new one was about $6 from the toyota dealer.

Disconnected battery before I took the brake off. Pressed it down a bit with a c-clamp and put new pads on while I had it off- the inboard one had come apart a little and was pretty super thin.

Anyway, I rented a hub puller to get the thing off, and took the whole mess to a machine shop. They pressed out the old bearing and put the new one in for me, charging $42 to do that.

Then I put the other set of pads on the other brake.

Problem solved. Noise gone. Yaaaaay!

oh yeah- cause of noise in the oem sealed bearing? I took it apart, found hardly any grease, and 200+k miles had worn a little groove in the race.