ZLH

Dear all

Newbie here, and would appreciate some help.

My Boxster (2.9 PDK) recently developed a loud high-pitched whining noise. It's so loud that the security guards at my house and my office came to ask if my car was ok.

A few characteristics:
1. It's quiet when started, and only comes on after driving a while
2. It continues after the engine's turned off for a few seconds before winding down
3. It happened a few times, but now stopped. Brought it to the workshop and they couldn't replicate the problem.


Clip of the noise can be found here:


Can anyone advise what the problem is? Many thanks in advance!

Macster

You mention the noise only appears after the car has been driven awhile which suggests the engine is hot enough the radiator fans are running or the engine compartment fan is running.

That the noise continues after the engine has been shut off my WAG is it is a radiator or engine compartment fan motor that is noisy.

If you want drive the car around until the engine is hot enough to trigger the radiator fans to come on. You'll have to be sure the A/C is off.

If you then hear the noise concurrent with the fans coming on just wait and let the fans run until the coolant temperature drops and the fans shut off. If the noise then stops, well there you go.

You can also get the engine compartment fan to come on then run until it shuts off on its own.

While the tech can command either radiator fan to come on or the engine compartment fan to come on the noise only appears after the source has run a while. If I'm right of course.

Another possibility is the noise is from the power steering pump. You sure the fluid level is ok?

Can you affect the noise by turning the steering wheel lock to lock? (Do not leave the wheel turned after this but bring it back to center.)

ZLH

Hi Macster

Many thanks for your help.

Sent the car to the workshop, and for three days they couldn't find the fault. Asked another Porsche restorer and they said if the noise goes away then there's probably nothing to worry about.

So the mysterious whining noise went away. Praying that it doesn't resurface again.

Thanks again.

Macster

Well, there is not much one can do if the fault/symptom can't be reproduced. I hope you were very observant and could provide plenty of detail of when the noise did appear? This is to help the tech follow the steps with the best success of reproducing the symptom in this case the noise.

But the way the tech minds works is no symptom (noise in this case), no problem. And that makes sense. With no clue what does the tech do? He can't just replace parts in the hopes the noise never returns again.

All I can advise is just keep an eye on the vital fluid levels, be a bit more vigilant than normal just in case it is a fluid problem. Try to be conscious of your driving routine so if the noise returns you can tell the tech what you were doing with the car from the time you started the engine until the noise appeared.

Ideally you would want to run the car by the shop with the noise but that is not always possible.

Qmulus

That sounds to me like a secondary air pump (air injection) with bad bearings. Boxsters use the same pump as Audis and they fail like this all the time. Eventually the pump motor will seize, and the noise will stop and likely burn up a winding on the pump motor armature. This may result in an engine code for secondary air low flow and a blown fuse for the pump.

The best way to test it is to put power to the pump (it is mounted on the top of the engine) and see if it is noisy. It should also run on a cold start, so put the top in service position, pull the top engine access cover, and do a cold start. It will be pretty obvious then where the noise is coming from, assuming that the pump hasn't already seized. If you did hear it for a while, and now it isn't happening anymore, my guess is that that pump has seized.

If you are mechanically inclined and the pump still runs, but is noisy, you can clean the carbon out of the inside of the pump and replace the bearings for a few bucks. Alternately, you can buy a new replacement pump (do a quick search on ebay for Porsche secondary air pump). Replacing it is a simple job. I have rebuilt a bunch of these (new, better quality bearings with better seals, cleaned up commutator, etc.) and once they are gone through they are pretty much as good/better than new. For what you can get a new pump for ($160 or so), it may or may not be worth even bothering to repair a damaged one.

HTH!

Anker Berg-Sonne

I have the exact opposite problem. A very high pitched constant whine after I start the car cold. Goes away as soon as the engine warms up. I notice it, wife hasn't.

Anker

Macster

That, if you'll pardon the expression, sounds like the secondary air injection pump running.

How these pumps sound varies some from car to car and ambient air temperature is a factor too. (Cars just naturally are noisier in colder weather.)

In the case of my Boxster the secondary air injection pump sounds like someone running a Hoover vacuum cleaner in the distance. I can't really hear the secondary air injection pump in my Turbo.

Normally the pump runs at cold start and runs until the #2 O2 sensors are hot enough to work and then signal that the converters are hot and working. The DME then switches the air pump off and concurrently switches to closed loop mode.

The pump is intended to supply extra air to the exhaust system just ahead of the converters. The extra air is to enable the burning of the extra fuel the DME is supplying to the engine at cold start. This burning of fuel heats up the converters faster and the DME can go to closed loop fueling sooner which results in a more efficient engine and less pollution.

Supposedly, the pump can run at other times if for some reason the converters get too cold. I've never heard the secondary air pump come on at any time other than at cold start though.

Anker Berg-Sonne

Thanks Macster, that has to be it!

Anker