Scrape...scrape...scrape sound when turning left

2004, 92K miles. I've recently noticed that when I am turning left, I hear an intermittent scraping sound.

I've looked in both front fender wells and don't see anything unusual. The plastic fender liners are secure.

My first thought was that a warped disc rotor is making intermittent contact with the disc pads, but why would the noise only happen when the steering wheel is turned so that the car is moving to the left?

I'm expecting that a bearing failure would produce a squealing noise while a CV joint failure would be demonstrated by a clicking sound when power is applied and removed.

 

Hi J, I raised up one front wheel at a time and had the car IG-ON and in N so that I could rotate the wheel. No unusual noise, and I was not able to detect any play in the bearing.

However, I think that you are right that the bearing is starting to go bad, so I'll continue to drive the car and see how long it takes for the symptoms to worsen.

Hi Hobbit, I've had two traction batteries out of three Toyota hybrids replaced under warranty, so that is one clue that my driving conditions might be more adverse than the "normal" driver.

Regarding the struts, I would guess that for those Prius with more than 60K miles on the odometer, probably 50% or more have bad struts but the drivers either aren't aware of that or have decided to motor on, regardless. Given the four-digit dealer repair cost, I am not surprised that most owners will defer replacement as long as possible.

 

TSB SU007-06 describes the criteria recommended by Toyota. The advantage of this criteria is that it is very easy to determine the amount of fluid leakage down the body of the strut or shock. The dealer should use this criteria to determine whether you are eligible for service under warranty.

The disadvantage of this criteria is that it is not 100% accurate. A strut may have failed without showing visible fluid leakage. For example, the nitrogen gas may have leaked out although the oil has not yet leaked.

A strut or shock is a mechanical device, not an integrated circuit. Therefore, it will wear out gradually and as you say, can be "semi-bad" for a prolonged period of time.

How do you know whether your struts are good or bad? One way is to compare the ride of your car vs. a new Prius of the same generation (however this is no longer possible for 2G). It's hard to be sure without removing them, taking the coil spring off, and comparing the force required to compress, with a new part.

I have recently replaced my front struts. Although one had definitely failed while the other was at 25-30% compared to new, the ride feel is not that different with the new parts. The main difference is that little irregularities in the road are no longer felt.

 

My Prius now has 94K miles. The scrape-scrape noise is still very evident when turning at low speeds (either left or right), and the car makes kind of a wuba-wuba sound when driving at speed.

I had my wife drive the car slowly in a tight circle while I walked alongside, listening to the noise. It seemed to come more from the right front instead of the left front. Then I raised up the car, one side at a time, and rotated the front wheels by hand while the car was IG-ON and in N. The right side makes more noise, a steady grinding sound. I don't notice any play when pulling on the tires. I do not see any debris in the front brake caliper. The CV joint boots are intact, no grease leakage evident.

Given the above, I have decided that the right front hub is the source of the noise and needs to be replaced. The brake pads are at around 4-5 mm so I am going to replace the pads and the front rotors while I am at it.

Given some of the other recent posts where people have had trouble unstaking the axle hub nut, I am wondering whether anyone can recommend a good tool that they know will work on the Prius. If not, I'll see whether I can buy the Toyota SST 09930-00010. The nut is set back quite a bit so many axle shaft threads are exposed and subject to damage.

I already have a 12 point 30 mm socket which will work nicely on the axle hub nut since that is also 12 point.

 

Thanks, J. An excellent idea.

For future reference, here's the net pricing and part numbers for the parts that I just ordered from Champion Toyota, Houston:

43510-47011 Front hub $67.69

43246-47010 Bearing cover 2004 - 2009 $12.97

90080-17238 Axle nut 2000 - 2005 $4.99

43512-47030 Rotor 2004 - 2008 $153.38 (qty. 2)

04465-47050 Front pads 2004 - 2008 $40.27

90468-16017 Cotter pin 2004 - 2009 $0.68

Sub Total:$279.98
Tax$0.00
Shipping$24.64
Total:$304.62

 

Thanks for the comments. Yes, the pad wear is uneven, but not to the point where a pad is only 1 mm or less.

I'm going to replace the rotors because they are not that expensive. However I'll measure the thickness of the old rotors with a micrometer and report on that when I do the job.

I found out that the price of the SST is $45 plus shipping which seems like a lot to pay for a very small chisel. So I'm planning instead to buy a set of Craftsman punches of varying diameter for around $15. That should work well to unstake the axle hub nut.

My parts order is delayed a few days because the rotors are being ordered from the Toyota regional warehouse.

 

My parts order just shipped today from Houston, so I probably won't receive it until Tuesday next week. Might have time to work on the car the following weekend.

My current belief is that the RF hub is bad, I'll find out for sure when I remove it and compare to new.

I bought a 12-piece set of Craftsman tapered punches (incl three small chisels, two nail sets, and alignment tools) from Sears the other day, on sale for $20. Also bought a 3" diameter wire brush for $5 and a set of nut drivers (metric and SAE) for $20 - so I ended up spending a similar amount as the SST would have cost, but obtained more tools and utility for the price. The purpose of the wire brush is to eliminate rust that is likely to be present when I remove the brake discs.

Hopefully the set of punches will give me sufficient diameter choices so that I can gracefully unstake the hub nut without causing damage to the axleshaft.