Rear wheel squealing
 

When I did the test drive on my 1999 boxster base there was a very annoying squeal coming from the drivers side rear tire. It was independent of applying the brakes and cornering. The seller said he had his Porsche mechanics look at it and couldn’t find any problem. When I picked it up a week later no squeal at all and nothing since I got it home. I had new tires put on. Nothing on the drive home from the tire shop. Then last week I picked my daughter up from school and it started faintly as I was leaving the school and by time I got home from a 15 minute drive it was incredibly loud. Metal on metal squeal. Again nothing to do with the brakes or cornering. I took it out this morning for a quick drive around the block and no squeal.
When it got loud the last time I drove it, it wasn’t a consistent squeal it had a bit of a in and out wobble squeal as the tire rotated. I haven’t tried to pull up on the emergency brake yet. The only consistent element to this was the outside temperature. Both times it was squealing it was high 70’s. When I drove the car with no squealing it was high 60’s low 70’s.

I once had a pebble caught between the dust shield and the rotor. Your symptoms sound very similar.

I had a similar high pitch squeal coming from the right rear several years ago. Couldn’t get a firm diagnosis on source of noise. Ended up replacing the wheel bearing and that took care of the problem.

Brakes or bearing. The come and go makes me think bearing. Easy fix if you stop driving it[emoji316]


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Could also be the bearing. If it is, you'd most likely have play in the wheel.

Thanks for all your suggestions, it makes me wonder if it is something in the dust shield or the bearing needs to be replaced why the former owners mechanics couldn’t find the problem. Would a wheel bearing be intermittent like this? Both suggestions make sense to me.

Play? You mean rocking it side to side... back and forth. Wobbly? Thanks!

There are a couple symptoms of a bad wheel bearing. The most common is a moaning sound related to speed. The other is play in the wheel, but you'd have to jack it up to check for it. Sometime the play isn't there, but usually the noise is.

Most recently I had a wheel bearing go bad in my Subaru with no symptoms at all, except it failed PA annual inspection. The mechanic pointed out to me that the wheel is wobbly. I had to see it for myself. It had play up and down as well as left-right. It wasn't the ball joint, nor the tie rod. He was actually surprised that when he test-drove it he didn't hear anything.

Yeah, my money is still on a pebble between the dust shield & the rotor. It could be the bearing, but you'd think the mechanic would have noticed it. It probably never occurred to him to look for a pebble.

One possible reason the noise is intermittent could be that when you go in reverse, it dislodges the pebble, and then over time it find its way back to that prefect place where the rotor rubs against it and causes the heat shield to basically harmonize and make the squealing sound.

The pebble theory makes the most sense to me I would think the mechanics would’ve spotted a bad wheel bearing when it was on the lift. I’ve had bad wheel bearings before on other cars and I’ve always noticed that they get louder when you corner. The sound didn’t change when I zig-zagged or cornered. Plus I would think a wheel bearing would be consistently noisy. This only has happened twice and I driven it about 10 times now around the neighborhood.

Yeah, and it doesn't cost you anything to look for a pebble. My wife's car had a pebble and I was amazed how polished the side against the rotor was! It looked like a tiny piece of a granite countertop.

Since you haven't heard it the last 10 times you drove it, maybe the stone ground itself down so small that it fell out. I wouldn't worry about it until it happens again. And if it does, drive in reverse for a while and see what happens. Then jack up the car and look for it. And while you're there you can check the wheel for any play.

Great suggestion. Thanks!

if there is a pebble caught somewhere you should easily be able to see score marks on the rotating part. If you don't see anything on the outer or inner brake rotor surface, it may be all the way on the inside surface of the strut carrier adjacent to the outer CV joint

and on the bearing, I have had two fail through the years, both times a rear. The first one was immediate, constant wailing noise, varied with speed. I knew what it was, waited three days to get the bearing and it was fixed in a day.
The next made the same noise...sometimes. it went away several times, then returned. I already had a spare bearing so we swapped it, sure 'nuff...bad bearing that you could feel in your hand, but no wobble and intermittent sound.
Go figure. varying noise with speed would be an indicator of either fault.
Point is, if you eliminate the pebble theory, that is your next likely spot, given the limited info we have here.

I agree, the previous owner thought it might be a bearing. Any idea what it would cost to fix at an independent shop?

I think the bearing is about 50 bucks...you need a shop to remove knuckle and press it in, so a couple of hours and an alignment. I think everything was about 400 bucks, although another shop quoted me 700. That was the day they lost my business. If you don't supply the bearing, they will rape you on that...both shops let me bring my own, otherwise the bearing would have been 250 parts.

I'm talking S model, the bearings might be different for the 1999 base

I’ll get it upon a jack later this week and check the bearing. If it is the bearing I should have play in the wheel correct? Also when I spin the wheel by hand I should hear something? Maybe the previous owner knew about the wheel bearing and didn’t want to spend the $400+ on the repair since he was selling it.

First question: Not always.
Second question: Not always.

to replace the rear bearings, if you remove first the half shaft you don't have to remove the hub carrier, this way you don't risk damaging the ball joint rubber booth and you will not require an alignment..

So when I get the car on a jack and check to see if there is any play in the wheel and/ or if there is any noise when spinning the wheel and I find I don’t have any play or noise I could still have a bad bearing? How do you know if you have a bad bearing if there are no signs?

Yes you could possibly still have a bad bearing even if you find no excessive play or noise when checking it. The sign is the increasing noise when you drive it. As you drive it could be heating up melting lube out, you get friction and expansion of parts, tolerances become less noise starts and increases.
I would first eliminate all other possibilities.
Make sure the noise is coming from where you think it is.!!!!!!!
If you have eliminated the pebble possibility look for other likely causes.
Brake pad wear indicators? bent backing plate? something rubbing on the axle? loose mounting bolts at axle to transmission.? If you eliminate every other possibility
what are you left with.????

You have to listen carefully as bearing noises can be hard to ID, usually they rumble under load, like if you turning hard to the right, you should hear a sound change on the left wheel..

Hopefully what I am trying to explain makes any sense..

Totally makes sense. If I can’t find anything I will go over to my local Porsche mechanic and see what they can find.

I do have one question, how dangerous is it to drive if the sound is so intermittent and it goes from no sound to the horrible squealing sound? I’d like it be be doing it when I take it to the shop.
I got to think if the bearing is compromised it should get hot and eventually come apart.

"Horrible squealing" is a clue. But your Horrible squealing could be my "Hmmm that does sound right" wheel bearings don't usually come apart they seize up.

When I have an issue with an automobile that I think is serious. (more so with engine or trans issues). I think long and hard before I drive or even start the car. (If engine related). Why???? Because all the moving parts are inter related one simple issue can become a blown engine or trans.

If what your hearing, seeing ,feeling, smelling, thinking, is wheel bearing, then you have to make a judgment call. drive to the shop or not.

how far is it? hiway or city streets? you can try it. If it starts to squeal pull over feel the hub for heat. let it cool down if hot. try again. Or you may just make it no problem;)
What ever happens let us know what you find. that helps us all learn.:D

If the tell tail signs of a bad wheel bearing are not there (play in the wheel, noise when you spin it on a jack) would the wheel at least be hot after a drive?

If it is the wheel bearing, and there's no play in the wheel, it sounds like it's in the VERY early stage of failing. I've driven daily with bad wheel bearings for months after I first noticed any noise, and it was making constant noise. Like Blue62 said, they generally don't come apart. They CAN come apart, but if they do, they have to get pretty bad before they go.. If I were you I'd first check for a pebble. If there's no pebble I'd keep driving it until the noise becomes more predictable before taking it to a mechanic.

This is a funny vid. I've never seen wheel bearing so bad that a driver in a DIFFERENT car can hear it!

https://www.youtube.com/watch?v=_lzd0gTwreQ

If it was squealing during the drive and you check the hub for heat I would think yes it would be hot or at least warm depending how far you drove it while acting up.

My question is..... are you 100% certain the noise is coming from the rear wheel?????
After all I assume you are inside the car when you hear it.

Could it be something else????? Water pump? power steering pump? Idler pully? Alternator? All those things are right behind your seats. sound travels.

take it for a drive and get it to squeal. see if you can tell if the sound changes with different engine RPM. see if the sound changes with different road speed.
If you have a standard transmission see if the sound changes with clutch pedal in versus out while moving.

The last time I drove it and it was louder than usual I thought it was definitely the wheel making the noise. It certainly modulated with rotation speed of the wheel but didn’t change when the brakes were apply or when I went around corners. It was so loud I thought for sure it would still be doing it the next day. But nothing when I drove it. I will be home tomorrow and will drive it and hopefully get it to do it again. I’d like to get this resolved before I take any kind of trip.

Keep us updated. Always interested in outcomes.

Will do. I appreciate all input

Something nobody has mentioned is the emergency drum brakes. If one of the shoes gets worn down to the rivets, or the return spring breaks, or ..., you can get the most horrible noises from them.

That is a good point

+1 excellent point. WRS, if the noise comes back, you may want to fiddle with the e-brake handle while coasting to see if the noise changes. I didn't even think about the shoes, I didn't realize they had drum e-brakes. (Porsche newbie) Actually, even if it's not making noise now, you can pull up on the e-brake handle momentarily WHILE HOLDING THE RELEASE BUTTON when coasting, and if the shoes are worn to the rivets you'll hear them.

An easy way to test your theory, is to drive it and slowly pulling the parking brake level to see if the noise returns..

there are two interesting things about this noise problem from the rear wheel.
(if it is the rear wheel)???
1. It was checked out by Porsche mechanics and no problem found. ……….
2. Comes and goes.
The E-brake idea is something I wasn't thinking of, good call.
I would think a half decent mechanic would have checked it though.
It is something the OP can check in the way described and perhaps find the problem or check it off the diagnosis list.
keep us posted;)

Over time, I replaced all 4 bearings on my 2000 Box S during ownership. A couple presented themselves in typical fashion and were easily identified. Two others were very subtle....no unusual noises while turning one way versus the other and no play felt by pulling on the tire. Anyway, all issues were solved by new wheel bearings, with all work happening after 100K miles.''

This car only has 39k. The emergency brake theory makes the most sense. The noise was not effected by my braking. I too think a good mechanic would have checked this. I thinking the previous owner knew about it and didn’t want to spend the money to fix it. If the emergency brakes need to be fixed I’m assuming they would do both? If so is this as much as a wheel bearing?

With 39k on the car the E-brake should have very little wear on the shoes if any. and should not be a problem. E-brakes are not usually used to stop a moving car.
I only set my E-brake after I am parked. So mine should never wear.
Now if someone drove with it applied or partly applied or abused it in some way that's different.
But testing it is easy: slowly apply it while moving if there is a problem with it you will know it.

Now that I see you only have 39k on the car I wouldn't think e-brake or wheel bearings would be a problem.
But being a 1999 that means it sat for extended periods of time. lots of strange things happen to cars that sit for long periods of time. My 2000S with 47000 when I bought it last July had no rubber left in the motor mount, rotted out mostly from not being driven.