Noisy rear wheel - bearing or tire?

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?

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.

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.

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.

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.

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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.

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.

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

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.

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.

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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.

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

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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

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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.

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

Thanks for all the replies guys. I got some time tonight to run out and swap the wheels (not easy to do, I live in the city). First off, the noise stayed on the passenger side after swapping the wheels. Pretty much no change at all. OK, so it's not just the tire itself. Now, I'll admit, I've know for a while that I could use an alignment (for other reasons). Looking at the rear tires, it's obvious that I have uneven wear, with the inside corner the most worn. I took some pictures, could upload them later tonight. Could this noise be caused by a bad alignment? I did the 9-12 test, pulling, pushing, etc. There is absolutely no play in the wheel at all. I forgot to check the lugs after my test drive - but I don't think they'll be hot. In the past, after 30 min+ drives, I've felt the brake drum, rim, *above* the lugs, etc for heat thinking that exact same thing. Noise = Friction = Heat. It's always been cool to the touch. I left the wheels swapped for now. I only did a 1/2 mile test drive, never got above 35mph and could hear the noise pretty much the whole time. I'm doubting the bearing right now (could change opinions tomorrow), thinking an alignment is in my future. Ben

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You are in denial! I did the same thing though, I even purchased a new set of tires. In the end, I replaced the right rear wheel bearing.

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Probably right...., but let's talk about the Porsche here - not the rest of my life On a more serious note, does anybody have the B90 bearing puller kit for loan? I see that Pelican also sells a kit (for $275) that is designed for these bearings. I'm more than happy to throw a deposit your way, but I'd rather not have a 1 time use tool laying around my garage. Ben

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Very unlikely alignment would cause the noise to instantly appear after you swapped tires. I agree with washington dc porsche: you are in denial. Wheel bearing. After having the wheel bearing taken care of, then have the car properly aligned due to the uneven tire wear. However... I guess if you are going to do an alignment anyway... you could do this first -- the bearing change should not affect alignment, didn't for my Boxster anyhow, but you need to double-check this is the case for your car. But I still believe there's a new wheel bearing in your car's future, immediate future. Sincerely, Macster.

yes... and you should replace both bearings. had a friend drive with bad bearings... warped the wheel carrier. Big money there....

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Ok, ok, I'm out of denial. Called up my local indy and he guessed $600+tax (impressed he would guess over the phone). Might as well buy myself a new toy and save some money in the process. So, I'm looking at the B90-P2 kit from Pelican. $275 seems steep, but I understand it's a good tool. However, after shipping for 35 bucks I started looking elsewhere. What about this kit here ? $333 and free shipping for the full master kit is hard to beat - especially as I might sell it afterwards (or loan it out to other locals). It should have the shoe to pull the hub, right? BTW: I did see some 928 owners who made their own puller out of PVC. I know it's inexpensive, but I'd rather avoid that route. Is there anyplace to get a rear bearing for less than ~$97?

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Sigh. I don't mean to come down too hard on you but come on? I paid $100 for the bearing 8 years ago. And the thing has lasted 150K miles (or more) and the other 3 are originals and have over 256K miles on them. Come on. How much under $97 do you think you're going to pay? just buy a genuine Porsche wheel bearing and install it properly and get the car back on the road. Sorry. I need a vacation. Sincerely, Macster.

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You want a *** !

My rear wheel bearing is probably going too, haven't really taken a look on how to replace it but last time I replaced the front wheel bearing on a Toyota, I removed the wheelhub/carrier and have a local shop remove and press in the new bearing. Is it possible to do the same on the 996? Thanks!

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Yes, it is possible. However, you'll mess up the alignment. The 996 WSM describes 2 ways of doing the project - with a press or with the bearing puller. Considering I don't have the shop space to buy a press, I'll stick with the puller idea for now. I guess considering I'm going to do an alignment after this, it's a wash either way. Actually, I did find a *** (***?) bearing at one of the online dealers for ~50 bucks. However, the specs on the page concerned me a little, so I just went with the pelicanparts one.

Hmmm....I'm on the fence on this one myself too. Local machine shop charged me $50 for bearing r&r but then again, 4 wheel alignment was recommended sometime ago by the dealership

If you tire is the Michilin Pilot sport with the v shaped tread pattern then is does get very noisy as it wears. I had a set and swiched to PS2s and things quieted down. Better than swapping wheels left to right is to have a friend with the same car and put his wheels on for a drive. In 5 miles you will have an answer.

You can also just check around and find a machine shop that can replace the bearing, just bring them the hub and the new bearing and its an easy job with a hydraulic press. I'm guessing it will be much cheaper than buying a set of tools you will only use once or twice.

Alright, all of the tools (B90 puller, bearing splitter & 3/4 drive breaker bar) and the new bearing have all showed up. I'm planning on tackling this job over the weekend with a friend. Any last minute advice (besides don't do it ). One of the few concerns I have is getting the half shaft itself out. I'd like to avoid removing any bolts from the suspension. After disconnecting it from the transmission, will it pull in towards the center of the car (fit under the transmission)? None of the guides touch on this part of the job - I can't remember how much clearance there was when I was doing my clutch.

Update here: Spent some time over the weekend pulling the bearing off the car. Unfortunately, the B90 puller cracked with the bearing ~1/4 inch out of hub (after beautifully pulling the spindle out). I resorted to the backup plan - fully pulled the carrier off the car and brought it over to the local indy. I'll let them push the old bearing out, push the new one in and mount the spindle. Now - the problem is timing. I doubt I'll have a chance to work on this for the next week or so. While I'm waiting, are there any other parts I should replace while I'm in there? The sway bar bushings look ok and the brakes have lots of life left. I did have to drill out one of the screws holding the rotor down, so I'm going to get a couple new ones. BTW: I'm still waiting to hear back from PelicanParts about either replacing/refunding the puller. I'm not going to fault the tool design until I hear back from the indy how hard it is to get the bearing out with a press. Ben

Im assuming your gonna need to bleed the brakes. Need new caliper bolts, hell... paint the calipers red while for at it.

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Very very tempted.... My friend helping me was pushing ferrari yellow. Actually, one other question. Is there anyway for me to bench test the CV joints in the axle (on the off chance that my wheel bearing wasn't making the noise in the first place)? Ben

Yes, you can open the CV joints up, clean them up well, and do a visual inspection - looking for any pitting. At the end of this video I show some examples: You Tube

Thanks Van. I did my own bench test on the CV joints... felt for any play or noise. I'm not sure if this 'test' is worth anything, but my CV joints are solid as a rock. I doubt they're the problem. Aker's Porsche in Seattle was more than helpful getting the old bearing out of the carrier and the new one in. PelicanParts on the other hand has been a PITA with getting an exchange for the bearing puller. I'm really disappointed with their service dept. A quick inspection of the old bearing showed..... nothing. No pitting on the *****, nor on the races. The guys at Akers agreed, but I know this wouldn't be the first cosmetically good bearing that was making noise. One thing I am thinking about. My axle nut didn't feel like 340 ft lb tight. I know my hands & back aren't a tuned torque wrench, but it came off much easier than I expected. I wonder if that was the problem all along. Anyways, I got out to the garage today, put the hub into the carrier/bearing assembly and put everything back together. My Pittsburg T40 wrench broke, which delayed me for a bit - but otherwise it was a very straightforward job. Went to go start the car up for a test drive and..... dead battery I guess I'll have to find out tomorrow if the fix worked or not - now out to the fireworks. Ben

Figured I'd post a follow up here - now that the problem is solved. It looks like I guessed wrong initially with the rear bearing. After putting it back in, the noise was still there. I decided to take it over for an alignment next to see what they would say. Overall my toe was over 6mm out (total) in the front) and other values were all over the place - I'm very glad I got this done. Once I left the alignment shop the noise changed from a high pitch hum to a 'whomp whomp whomp'. With a little help from a friend we quickly pinpointed it to the front wheel. Well, the front bearing is much easier to do than the rear. I was even able to do it all on the car and didn't have to touch the spring pearches (every diy I looked at either removed the spring completly or took the hub off the car). Now that both jobs are done the car is silent going down the road! If anybody wants I can post some pictures I took and a mini diy of doing the front bearing with the hub staying on the car. Ben

While tinkering try inspecting the transmission mounts. There's one on top you can not tell is broken till dropping the engine like I found out while putting a new engine in. Being broken it allows the trans and engine to ride out of specs. Car sure tracks in turns better just because of the mount replacement. I'm thinking the broken mount was allowing some bad geometry which can add noise from the rear tires and such. Good luck.

Had this same issue, just got the 996 looked at my a certified tech and looks like both my rear wheel bearings need to be replaced. The labor is $$$

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Just curious, do you track your car often and do you run any wide wheels or spacers?

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No no and no lol. Completely stock and daily driven . Im glad it happened now then later though. Rather bite the bullets for things now that down the road.

Mine has a lot of noise from the rear tires on the highway. I am pretty sure it is the tires Michelin AS/3. The noise changes a lot depending on the road surface. On grooved concrete (as most freeways are here) really noisy. On smooth asphalt, reasonably quite. I can't wait until those f@#$%ing tires wear out so I can replace them

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Thanks for posting this video, I found it very informative.