healey1968

So I've been battling a noisy rear wheel for the past 9 months (~5k miles). It hasen't exactly gotten worse, but now that I can put the top down, it's annoying the out of me.

First off, I'm trying to figure out one way or another if I'm working on a noisy tire (Michelin Pilot) or a wheel bearing (or something worse). I know for sure it's coming from the rear passenger area. I can hear it faintly from inside the cab and pronounced when driving next to a wall. Other people only hear it when we're driving next to a wall. The noise itself is a ... well, it's a whine. It's really between a loud 4x4 tire and a honest to goodness failing bearing. The noise takes a while to start, maybe after 2-3 miles of driving. Once it starts, it'll be there at any speed.

I've tried jacking up the car and checking for wheel play - which these isn't ANY. Spinning the wheel on a jack stand just sounds like the brake pads against the rotor - no bearing noise either. Even with this data, I'm still really leaning towards a bad bearing. Note: But why would the noise have not changed at all in 5000 miles of driving?!?!

1) What else can I do to narrow down the noise? Can I take the driver rear wheel and swap it with the pass rear wheel? Is there any uni-direction problem I need to worry about with the rims? This is only a temporary diagnoses thing. BTW, I have no spare to throw on there.

2) Assuming this is a bearing, should I do the job myself? I'd need to buy a B90 puller (or borrow one in Seattle). I've done a clutch and the other bearing, so I know how to turn a wrench. However, I do have limited garage space.

2a) If I pay somebody (Akers Porsche), how much should I be looking at? I saw a thread from 2006 saying $350 bucks. Is that still reasonable?

San Rensho

Swap the rear wheels left to right and if the sound moves to the left side, most likely the tire/wheel. If it stays on thye right side, then likely a bearing. Could possibly be a bad CV joint? Check the boots to see if they are ripped.

Don't leave the wheels swapped however. Since the tires are directional, they won't shed water in the wet and you could also piossibly have some handling problems, so take it easy with the tires swapped.

nick49

In a parking lot or twisty road quickly steer from right to left to right a few times like doing a slalom. The noise will change if it's a bearing, not if a tire.

redridge

lift the car up and wiggle the tire... if it has a play, then possible bad bearing, try spinning the wheel for noise as well .... I would change both bearings though.

function12

After driving the car touch the wheel studs. If they are hot you have a bad bearing or could dragging brake. They will be warm but not HOT. Be careful you can burn your finger. Could have something stuck between the pad and disc too.
Not the most scientific but it works.

machbx

I am running the same tires - they were just put on b4 I bought it - I actually had to get my step-dad in the car and drive - I could swear I had a bearing problem - 996 sounds like a dump truck or like I 4 x 4. Nope - and not only that - these tires are supposed to very well thought of - and less than 1k on them - I hate them - but they do handle good - I just hate the noise.

Van

I've been having rear bearing noise, too. I just ordered bearings from Suncoast and borrowed a SIR tool - but it will be a few weeks before I actually tackle the job.

healey1968

function12,

I've tried feeling the wheel for any heat after long drives (30 miles+). The wheel is always cool to the touch. I'll try swapping wheels tonight and see how that goes

function12

Not the wheel but the wheel botls (lug nuts).
When you swap the wheels before you take them off. Jack the car up and grab the tire at 12 and 6 and see if you get any movement. You should need get any.

Byprodriver

Insure all tires are at proper inflation psi. Stick your head Way underneath car to inspect tire for unusual wear pattern & exposed steel belts, nails etc. Now you are ready to feel the surface of the tread for irregular tread wear that you didn't notice visually. Since it is a Michelin tire, if the tread feels smooth the tire is unlikely to be causing the noise. If you feel roughness in the tread you can rotate the rear tires to confirm the suspected tire, this will cause no harm other than reduced water evacuation from the tires. I did not see your 996's mileage but of course the higher the mileage the better chance of having a worn bearing.
The usual suspect in these cases is inner edge tire wear caused by improper alignment.

Macster

Michelin tires are not as noisy as they wear/age as other brands, based on my experience running them on my Boxster.

The only wheel bearing trouble I had was after I replaced a set of very worn and very very noisy Pirelli tires (now this is a tire that gets noisy as it wears/ages) the shop manager reported after a short test drive he believed a wheel bearing was noisy. He was not sure which end let alone which side, though he believed it was a rear bearing.

I said just replace both but he balked mentioning the cost.

So, I took the car out and heard what could have been a wheel bearing, since the new tires were obviously contributing very little to the noise level of the car.

My guess had the driver's side rear wheel as the suspected one and this may have agreed with the manager, though as I mentioned above he didn't know or wasn't saying at any rate which bearing he suspected.

Anyhow, the bearing was replaced: $100 for parts (this was back in 04 or 05 now), and I forget the labor but the total cost came to close to $500.

The good news was we were right, guessed right anyhow, and the bearing replaced was the bad bearing. The other 3 bearings are the original bearings and now have over 256K miles on them. The replacement bearing probably has over 150K miles on it.

What does this mean for you?

Couple of things. If the tires, or tire is worn out or close to needing replacement replace the worn tires. Chances are unless the bearing gets real bad you won't hear it until the tires are replaced and the new tires quiet the car.

I'm not a fan of continuing to drive one of these cars with a suspected bad bearing.

Before you replace the tires, though, check the tires for signs of abnormal wear. My 996 Turbo developed a noise that had me thinking wheel bearings but the source of the noise turned out to be a bit of mis-alignment (accidently pulled too far into a parking space and the fronts tires bumped into a low curb which was enough.. the car was barely moving)..

Anyhow, this was enough to knock the alignment out -- which I strive to keep in spec -- and this mis-alignment had the front tires cupping and howling to a bothersome level as I drove down the road at speeds above 70mph.

When the Porsche service manage relayed what a senior tech who test drove my car reported that the alignment out the SM demo'd to me the tire wear.

One could feel the tread surface and detect the cupping. It was rather noticable and as someone who spent a lot of time in a tire store when I was young (my dad ran a Goodyear tire store for some years) I was ashamed to have missed this obvious clue.

The alignment wasn't out that much either for I wanted to get the car aligned but the SM said the tech said it wasn't that bad and the alignment could wait until I replaced the tires.

I drove the car home -- nearly 2K miles -- with the alignment out but had the car aligned once I got home to quiet the car which the alignment did. Front (and rear) tire life didn't seem to be that much affected by the alignment but it was off and like the tech said it would be. (Mainly front toe.)

If you can feel the tires showing signs of cupping or some other abnormal wear after you replace the tires have the car treated to a proper alignment.

If the tires are still servicable haven't worn too unevenly have the car aligned. The alignment results may not be as good as they would be if the tires were all new or at least worn evenly but it will be better than leaving the car as it is.

And if my experience with my car is any indication the alignment will have the car quiet again, provided of course, that the alignment was contributing to the noise.

Oh, about the Boxster and its bad bearing: The wheel with the bad bearing exhibited no excessive or abnormal play. As best as the shop owner and I could tell all 4 wheels/bearings felt the same and there were no other signs of any bearing troubles. The only symptom/sign of a possible bad bearing was the noise and this was masked by the worn tires and only really made itself known once the worn tires were replaced.

Can't help you if you want to do this job yourself. Takes special equipment though probably not that expensive to come by but unless one's going to replace bearings on a regular basis... my recommendation is to have a reputable shop do the job.

Sincerely,

Macster.

Gretch

Having been through a bad wheel bearing I can say that this procedure is not a reliable method to determine a bad bearing.

machbx

Thx! This is *very* helpful to me - my step-dad is a 30+year goodyear man - from looking at my wheels - road rash - and I don't know when that happened - makes sense in having it looked at again since he was certain that it's the tires - and certain that I want to keep this brand/tire on my c4

washington dc porsche

Ditto.

I came to rennlist knowing that the noise didn't occur when turning right but other than that the noise was constant.

I tried all of the tricks mentioned in this thread and none applied to my situation. My cost was $650 for one rear bearing changed at an Indy.

porsches996

Best way to know...transfer weight and wheel stud hot to the touch...you can't miss it.

Robert