HELP: Abnormal Humming Sound increasing w/ speed
 

:confused: I have a 2000 Porsche Boxster S with 18k on it, "Pre-Owned Ceritified" with about 8000k since I picked it up from Porsche. Just recently I noticed that with increased speed, comes a lounder humming sound that appears to be comming from the engine compartment or the back of the car. This sound is seperate from an accleration engine noise and remains constant when you lay off the gas completely. It is especially noticeable with the top up & seems to almost contain this annoying higher-pitched humming. For example, when accelerating to 70mph on the freeway, the sound gets louder and louder...when rolling at this speed with no gas applied, it still makes this sound. It only occurs when moving, and the faster the more humming. Therefore, you cannot here this humming when you start the car or at rolling speeds. It is not unbearable, but definitely noticeable and abnormal.

The car has 17 months left on the warranty it isn't a problem to bring it in an get it serviced. I'm curious if anyone has any ideas as to what the problem might be before I go to those lengths. Thank you!

Is the sound more mechanical sounding or more of a natural sounding hum?

The first thought that comes do mine, since its a low mileage car, is the tires, is your Boxster equiped with aggressive rain tires or even snow tires?

It does sound like tires. There could be several reasons for this.

First, the tires are worn. If they are still the factory tires, I'd be surprised if they had much tread at 26K miles.

Second, the tires were rotated on the rear and are now facing the wrong direction since they are not made to be rotated. This means that you might have treads facing the wrong way and causing the humming.

Lastly, some tires get louder as they wear - even with quite a bit of tread left.

Thank you both for your prompt response and assistance! The tires are a soft summer variety, type: Continental Sport Contact 2's. They haven't been rotated and appear to be on the correct sides. There still is quite a bit of central tread, with the side tread somewhat worn towards the very outer edge of the sidewall.

As for natural sounding, it def does not sound "natural" but neither mechanical, as might be the case if it was a grinding sound. It definitely was not originally there.

After hearing your thoughts, I will pay attention to the tires to see if they are the culprit. On the other hand, when I lower my head towards the rear interior carpet above the glove right in front of the engine, the sound seems louder?

I'll let you know what I come up with after closer observation when driving.

Thank you! :)

I would be interested to see what you found out. I have a 2001 Boxster S with around 15K miles on it. I've had the same issue with a lower pitched humming noise. The higher the speed, the louder it gets. I took it to a Porsche Specialy shop and they said it was bad bearings on both rear wheels. I had them replaced ($$$) and it seemed for a while like it was better, but now it's back. : (

Please let me know if you ever found a solution. Maybe it is just the tires....

Tires could be cupped or out of round. Also, possibly the beginnings of a wheel bearing failure!

Hi- I JUST went through this... It was litteraly as you described it.
People said it was my tires as well, Its not- it the wheel bearings. Mine was covered under warranty- and when it was fixed, I couldn’t believe how long It had been getting louder... the car seems Lexus quiet now.

Good luck!

Subgraphic-I'm here in SD too with an '02 S. How many miles were on your Box when the bearings went? Was it fixed under CPO? I may have the same problem-or it's tire noise...

Thanks!

One thing to note... those tires have been unmounted and swapped to the other side. The Boxster wears out the INNER edge of the tire, not the outer edge as you described. Some people have the tires unmounted and swapped to the other side so the rotation is still correct, but now the inner edge is one the outside. Gives you a bit more tire life.

On the other hand, I just put new BF Goodrich Geforce tires on mine, and I still have what I thought was tire noise coming from the rear. I may have wheel bearing starting to go as well. I'll wait until I get my lift if they have to be changed.

How much does it cost to replace the wheel bearing in the left front/driver's side wheel? I found the wheel bearing to be fairly cheap, only $70.00 but I'm not sure of the labor cost. Anyone know?

I had an accident LAST OCTOBER and they fixed my car though my insurance's shop that was NOT a Porsche specialist. I told them as soon as I brought it in to pease check the wheel bearing becasue that's where most of the impact was. The left front bumper and wheel/tire hit a gaurd rail doing about 30mph. They said they would only change it, if it was needed. I said, how can you even tell unless you open up the hub to see if there is any damage? They basically ignored me, and saId they would be able to tell. Car rides fine up to 65-75mph and then after I go faster than that I hear a repeated humming noise. I definately think it's a wheel bearing because I know they did NOT replace it. My problem now is going back to them and getting them to fix the problem and having to get my insurance adjuster ride along with me over the speed limit posted. I'm not sure what they will say about me speeding in order to get them to hear the noise. I know when they tested it, they did not go above the speed limit of 65. Any sugestions. Here are some pictures of my car after the wreck. They had to replace my left front radiator, and the upper and lower control arms, and of course the rim, because the lip was ruined.
http://i5.photobucket.com/albums/y15...h/IMG_3446.jpg
http://i5.photobucket.com/albums/y15...h/IMG_3445.jpg
http://i5.photobucket.com/albums/y15...h/IMG_3447.jpg

Personnally I don't see how it could be wheel bearings??? If you do a search on here you'll see others with this type of sound, me included at one time. For me and many others, it was the air going over the front bumper and hood. If the gap between the two is not right you will get a humming type of noise that is independent of your engine speed. The adjustment to the bumper is easy to do and will fix the noise. I suspect that while your car was in the shop, they might have loosened the front bumper or hood to look it over. Also, others have found noise from the side mirrors...check this out before you get new wheel bearings. I hope this helps.

I wish it was that simple for me, but I'm getting a vibration along with the noise at high speeds. Feels like it comes up from the left front side of my car. I can feel it in the steering wheel and as my foot rests on the clutch, so its definately something they missed when fixing it. Could a warped brake dust shield cause this problem. Instead of replacing the bent one, they just pushed the metal back into place and put it back on. I requested that they replace it completely instead of just bending it back. I suspect this could cause the airflow around it to vibrate if it wasn't completely flat or still slightly warped. I hate dealing with these guys. I have to go back to them if I dont' want to pay for it out of my own pocket. :(