Humming coming from my 01 Boxster, any suggestions on what to look for

[Jasper7821]

I've had my car for 6 months and always cruise around with the top down.
Now that it's getting cold I put the top up sometimes.
Now I can hear a humming that goes along with the speed of the car. Any suggestions on what it could be, the car runs great.
Motor RPM doesn't matter, it's louder as the car speeds up and under 20mph or so I can barely hear it. On the freeway at 80 or so it's not horribly loud, but definitely noticeable.
Warm or cold, it sounds the same. And I don't think it's the tires.
Here's a link to the video and you can hear the noise if anyone can assist.
https://1drv.ms/v/s!Atil9WC21-BZ4Fk4zp5IyLVEJ0gv?e=uVQXhG
Thanks,

[Beelzy]

107k miles? Wow
Is the sound coming from behind you?
If so, maybe the idler pulley is going out.

[piper6909]

Sounds like a wheel bearing to me. Hunting down which one is a bit tricky. You can try jacking the car up. For the front wheels, try spinning them by hand and see if it feels "crunchy." For the rear wheels, you'll have to run it in gear and listen for it. Just be damn sure you have the front wheels blocked well. If you have a friend who has a lift you can use, that would be the safest. Sometimes they develop some play in the wheel, (but not always) so you can check for any play by wiggling the wheel side to side and up and down.

[Jasper7821]

Originally Posted by Beelzy

107k miles? Wow
Is the sound coming from behind you?
If so, maybe the idler pulley is going out.

Thank you, it for sure is coming from behind and sounds like it’s right behind me in the engine compartment.

[Jasper7821]

Originally Posted by piper6909

Sounds like a wheel bearing to me. Hunting down which one is a bit tricky. You can try jacking the car up. For the front wheels, try spinning them by hand and see if it feels "crunchy." For the rear wheels, you'll have to run it in gear and listen for it. Just be damn sure you have the front wheels blocked well. If you have a friend who has a lift you can use, that would be the safest. Sometimes they develop some play in the wheel, (but not always) so you can check for any play by wiggling the wheel side to side and up and down.

I first noticed it when I put the top up for the first time and drove on a 2,500 mile trip to California and back. The sound is only a little louder from before the trip. I would think after that many miles if it was a wheel bearing, it would be totally damaged by now and grinding. There’s no grinding sound at all, only a humming directly behind me.

[pilot4fn]

Originally Posted by piper6909

Sounds like a wheel bearing to me. Hunting down which one is a bit tricky. You can try jacking the car up. For the front wheels, try spinning them by hand and see if it feels "crunchy." For the rear wheels, you'll have to run it in gear and listen for it. Just be damn sure you have the front wheels blocked well. If you have a friend who has a lift you can use, that would be the safest. Sometimes they develop some play in the wheel, (but not always) so you can check for any play by wiggling the wheel side to side and up and down.

If the engine RPM contributes no change to the sound, my bet is in the wheel bearing as above mentioned :dance:

[Gilles]

+ 1 on a wheel bearing.

If you can find a long downhill street (w/little traffic..) turn off the engine and let it roll :-)

While going downhill turn to the Right and see if the noise increases or goes away, if increases then it will be your left side bearing, and if you turn Left and the noise increases then would be the right side bearing.

Regardless, with the mileage you should replace them at once as the other ones are right behind.. The bearings are easy to replace but it's a bear of a job to do it (physically)..

[Jasper7821]

Found this video, kinda sounds the same. It does sound like it may be a wheel bearing. I guess if it is and turning the wheel would tell me if if it’s in the front right? No sound difference when turning the wheel would mean it’s the rear? I went through the records that are pretty complete from new and don’t see the wheel bearings ever been changed. I see axles removed and new CV boots a few years ago.


https://youtu.be/UpsLaSzcAu4

Originally Posted by Gilles

+ 1 on a wheel bearing.

If you can find a long downhill street (w/little traffic..) turn off the engine and let it roll :-)

While going downhill turn to the Right and see if the noise increases or goes away, if increases then it will be your left side bearing, and if you turn Left and the noise increases then would be the right side bearing.

Regardless, with the mileage you should replace them at once as the other ones are right behind.. The bearings are easy to replace but it's a bear of a job to do it (physically)..

[Gilles]

Originally Posted by Jasper7821

Found this video, kinda sounds the same. It does sound like it may be a wheel bearing. I guess if it is and turning the wheel would tell me if if it’s in the front right? No sound difference when turning the wheel would mean it’s the rear? I went through the records that are pretty complete from new and don’t see the wheel bearings ever been changed. I see axles removed and new CV boots a few years ago.


https://youtu.be/UpsLaSzcAu4

Jasper, when you turn to the right (a hard long turn IF possible), you will put the load on the left side bearings and you will know if it's a front or a rear one.

[Jasper7821]

Originally Posted by Gilles

Jasper, when you turn to the right (a hard long turn IF possible), you will put the load on the left side bearings and you will know if it's a front or a rear one.

Thank you, I’ll try when I get home and and see if I get any results.

[Gilles]

Originally Posted by Jasper7821

Thank you, I’ll try when I get home and and see if I get any results.

Please remember that this 'technique..' only works with the engine off, rolling downhill :-)
good luck!

[piper6909]

Originally Posted by Jasper7821

I first noticed it when I put the top up for the first time and drove on a 2,500 mile trip to California and back. The sound is only a little louder from before the trip. I would think after that many miles if it was a wheel bearing, it would be totally damaged by now and grinding. There’s no grinding sound at all, only a humming directly behind me.

Wheel bearings can last thousands of miles after first hearing noise from them.

[Jasper7821]

Did the test and it is not coming from the front, turning the wheel at speed both ways made no difference.

Originally Posted by Gilles

+ 1 on a wheel bearing.

If you can find a long downhill street (w/little traffic..) turn off the engine and let it roll :-)

While going downhill turn to the Right and see if the noise increases or goes away, if increases then it will be your left side bearing, and if you turn Left and the noise increases then would be the right side bearing.

Regardless, with the mileage you should replace them at once as the other ones are right behind.. The bearings are easy to replace but it's a bear of a job to do it (physically)..

[Gilles]

Originally Posted by Jasper7821

Did the test and it is not coming from the front, turning the wheel at speed both ways made no difference.

Jasper, regarding your driving test were you able to hold the steering wheel for a moment or so, to allow you to load the bearings?

If your wheel bearings are ok, the only other thing to check are the CV joints...

[Jasper7821]

Originally Posted by Gilles

Jasper, regarding your driving test were you able to hold the steering wheel for a moment or so, to allow you to load the bearings?

If your wheel bearings are ok, the only other thing to check are the CV joints...

I live close to the base of a mountain, so I went downhill straight from 40-70mph and jerked the wheel both directions and no difference. Then I went on a twisty road and drove a few miles fairly hard with holding the wheel steady on the curves and still no difference in sound.
So I think it’s definitely in the rear. Any way to check if it’s the CV joints. And the boots were changed a few years ago.

[Jasper7821]

I talked to the dealer and they said it possibly could be a pilot bearing or throughout bearing, or a transmission gear bearing.

[piper6909]

Originally Posted by Jasper7821

I talked to the dealer and they said it possibly could be a pilot bearing or throughout bearing, or a transmission gear bearing.

Doubt it. A bad throw out bearing only makes noise when your foot is on the clutch. When your foot is off, the bearing has no pressure on it. So that rules that out.

I doubt you'd hear a bad pilot bearing. Even if you could, a pilot bearing would make a noise relative to RPM. You said the noise relative to speed, not RPM. So that rules that out as well. So much for the Stealer's opinion.

Also, CV joints usually make a clicking noise at low speeds, so I'm ruling out CV joints as well.

I'm still going with wheel bearing. And just because you don't hear a change when you steer in different directions, it doesn't NECESSARILY rule out the front wheel bearings. It's a general rule of thumb, but there are exceptions to the rule.

BTW, it could also be a bad tire, but I doubt it.

If you can, try the methods I outlined earlier. Otherwise take it to an indy for diagnosis.

Here are a couple helpful videos:
https://www.youtube.com/watch?v=YvKWGjmPKoc

https://www.youtube.com/watch?v=nl7cU2wHBXg

[Jasper7821]

Thank you, I’m hoping it is the wheel bearing. I don’t have access to a lift, nor do I have the tools to change a wheel bearing. The dealer wanted $1,500 to change the front and $1,500 for the rear. Maybe just have to take it in and let them see what it is.
And the tires are fairly new so I’m pretty sure it’s not that.

Side note, from your username, are you a pilot. I used to have a 76 and 77 Arrow and miss it dearly.
Thanks again.

Originally Posted by piper6909

Doubt it. A bad throw out bearing only makes noise when your foot is on the clutch. When your foot is off, the bearing has no pressure on it. So that rules that out.

I doubt you'd hear a bad pilot bearing. Even if you could, a pilot bearing would make a noise relative to RPM. You said the noise relative to speed, not RPM. So that rules that out as well. So much for the Stealer's opinion.

Also, CV joints usually make a clicking noise at low speeds, so I'm ruling out CV joints as well.

I'm still going with wheel bearing. And just because you don't hear a change when you steer in different directions, it doesn't NECESSARILY rule out the front wheel bearings. It's a general rule of thumb, but there are exceptions to the rule.

BTW, it could also be a bad tire, but I doubt it.

If you can, try the methods I outlined earlier. Otherwise take it to an indy for diagnosis.

Here are a couple helpful videos:
https://www.youtube.com/watch?v=YvKWGjmPKoc

https://www.youtube.com/watch?v=nl7cU2wHBXg

[willw]

I don't think I would take it to the same dealer who told me it was a pilot bearing. Do you have any independent Porsche shops in your area? Your local PCA chapter can help you find one.

[Jasper7821]

Originally Posted by willw

I don't think I would take it to the same dealer who told me it was a pilot bearing. Do you have any independent Porsche shops in your area? Your local PCA chapter can help you find one.

Thank you, I’ve only had the car for 6 months and it’s been perfect so I haven’t searched other shops yet, but will.
Thank you