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Differential noise

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I have just purchased a 99 Boxster, my first Porsche since my 87 944T. I have noticed a noise in the rear when letting up on the accelerator, like a bad CV joint.

I haven't had a car where I was so close to the engine and drive train before, is this a normal sound or should I be concerned?

Any advice? The car only has 20,000 miles on it.

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Come to San Jose with a full tank so I can drive your car.

There is no way to figure out over the internet if a noise is normal or not. Try driving another Boxster under the same conditions and see if you hear the same thing.

You are right, the engine and drive train are inches from where we sit. I keep thinking I hear a bad rear wheel bearing - but I have been thinking that for 31k miles.

My free advise is to just keep on driving. If you have a CV joint going bad it will let you know, but the 2.5 Boxsters are not know for having problems with the CV joints. Jeff

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  • 2 months later...


I was searching this site for an answer to some noise I noticed the last few times I drove my 99 Boxster. I have had the car for 9 months and the top has been down the whole time (I only drive it on clear days) and now that I have put the top up, I hear a noise loud enough to make driving a pain. I comes from what sounds like both sides of the rear, and sounds like a "wank-wank" noise that increases and decreases with the speed of the car, with or without the clutch in. At slow speeds, it sounds like when my old 914s would have bad wheel bearings. However, swaying from side to side doesn't seem to change the sound or the loudness like a wheel bearing normally would.

I know that trying to diagnose over the net is impossible, but does anyone else have this problem? A friend told me to go drive some other Boxsters from used car lots and see if they do the same.

Anyone with any ideas?

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Loren has a much better memory than me.

So others do not get paranoid, the TSB is for just 36 manual transmission cars that may have had incorrect differential gears installed. All are Finland cars. The VINs are listed on the TSB. They are all MY98 which you can tell as there is a W before the U. The car is inspected to determine if in fact improper gears were installed.

A recall notice was supposed to be sent out in June 1998. For general info any Porsche dealer can take your VIN and call a special number and a recording will say if there are any recalls for your car. The recall number is 298. For more general info any dealer can tell on the computer what warranty or recall work was done by any other dealer. Jeff

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  • 4 weeks later...

Hey, I never made it to the dealer with all the holiday duties. I did however, jack up the rear and spin the back tires with the brake pads out. The left side sounds like a grinding noise and the right side sounds okay.

Have any of you ever replaced a rear wheel bearing on a Boxster? I have done it on several 914s, and it was easy.

If you know how, would you mind giving me the steps?

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I have not done it on a Boxster. I sure did a lot of them on my 2 Fiat X1/9s as they had a poor seal design which permitted water to get into the bearing and wash the grease out. I went over to Pelican and the 914 has the same type of wheel bearing as the Boxster and Fiat. One piece with 2 rows of ball bearings.

In my poor student days on my Fiat I would remove the wheel hub housing and take it to a shop so they could press out the hub, bearing, and press in the new bearing. Then I bought the tools so I could do it myself on a work bench in a vise.

It is the same way in the Boxster shop manual. They show a hydraulic press with adapters to take it apart and to press in the new bearing. They do say you need to heat the housing to get the old bearing out and the new bearing in. The Fiat shop manual said the same thing but the bearing was never that tight of a fit.

The wheel bearings are known to fail on a Boxster - more so on cars that have been tracked. Does it make noise on turns is my test. If you can do it on a 914 you can do it on a Boxster. Pull the housing and take it to a machine shop with a new bearing. Jeff

Boxster bearing.


914 bearing with grease seal removed.


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Toolpants, thanks for the quick reply! I called the dealer and didn't feel good about our conversation. I then called a couple of local shops. One guy, who has been working on Porsches for over 30 years, told me he had never heard of one failing on a Boxster. He had on all the other models. I called another shop that has two ex-dealer mechanics, and they said they had never replaced one, but would give it a try.

The symptoms are not like they were on my 914s. It makes a rough sound when I spin the wheel (with the pads out) on the drivers side rear. But it doesn't increase or decrease when swerving. It also gets louder the farther I drive. Could that be something else other than the wheel bearing? I don't want to go to the trouble myself and find out that was not the problem. Also, how do you go about removing the bearing housing? Like I said, I don't have the shop manual, and I don't want to break anything.

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