Two days ago my 2007 987.1 base started making a really high-pitched whine which coincided with my need for a new battery. I thought the problem was related until I put in the new battery and the problem seems to actually be even more noticeable. My first thought was it was the dreaded
AOS
but with the engine running and the whining noise going, I can unscrew and take off the oil filler cap no problem. This leads me to believe it’s the cooler control valve. I am a good two hours from anyone who will work on my car so I try to do most things myself. A search found a Facebook Porsche technical group in which a shortcut was recommended to just replace the vacuum part.
Questions:
1. can I drive the car any distance at all with the sound occurring?
2. does the vacuum replacement easy fix sound like a logical and safe solution?
3. Based on the sound you can hear in my video, do you also think that this is the correct problem?
thanks in advance!
Big clue - new battery makes noise worse. That clue, and the sound itself makes me think you may have an
alternator
issue. I've heard alternators make this sort of noise when a diode (which rectifies the alternating current the
alternator
makes into DC that the battery and electronics want) shorts out. And if the load on the
alternator
changes (like with a new battery that perhaps wasn't fully charged when installed) - that could result in the noise getting worse.
Answers to your nicely numbered questions (I really LOVE that sort of question..)
(3) That's just a guess without being there with my mechanic's stethoscope (about $5 at
Harbor Freight
) and with the engine panels off so I could probe around with the stethoscope. It also is possible one of the idlers on the serpentine belt has a bearing going bad or the AC compressor or even the water-pump - could make that sort of whine.
BTW - I can't recall ever hearing about a failing
AOS
causing a whine of any sort. What fails is a rubber diaphragm in the
AOS
allowing engine vacuum to directly suck on the crankcase. Maybe a whistle like noise, but what I'm hearing in your video (which is no substitute for 1st hand inspection) has a metallic component to the noise.
(2) I'd suggest (1) buying the stethoscope (2) removing the front engine panel (fairly easy to do) and probing around the
alternator
and serpentine belt to see if you can localize the noise. Don't get the tip caught in the belt..
Let us know what you find. And - Facebook is possibly the worst source for technical advice I've ever seen. At least half is just plain wrong with no real thought behind what's posted, another quarter is people not understanding the question, and the final quarter is people trying to be cute and suggesting things like "
AOS
" or "
IMS bearing
" or "bore-scoring". Use Facebook advice at your own risk.
(1) Would I drive it any distance sounding like that? Nope. Not without poking around trying to determine what's causing it.
The video sound was only at idle. Does the sound change any in pitch or loudness with slight changes of RPM? Don covered many good points. You need to know if the whine is coming from a belt driven accessory.
No. No change when revving. I’ve been afraid to drive it to see if it stops when driving or at right speed.
A question: does this noise occur when the car is started cold (i.e., sitting overnight off)?
The reason I ask.. the noise seems more noticeable on the starboard side (passenger in the US) near the air vent and the wheel arch opening.
That vent is where the fan that cools the engine compartment is located. I had no idea just how noisy that fan is due to it rarely ever running. On my car it only seems to run once in a while on a really hot day after shutting down the engine (engine compartment heat rises from the hot engine just sitting there), or after a spirited drive in really hot weather if the car is idling for a while. The noise it makes is a constant speed whine, there will also be noticeable air exiting from the vent on the port (driver's) side.
I think we need a video, a bit longer perhaps, with the engine RPM changed while recording the video.
FWIW - there are lots of things being spun by the serpentine belt. I believe the 987.1 has two idlers on the belt, one is spring loaded to tension the belt, the other stationary used to turn a corner. There is also the water pump, AC compressor,
alternator
and power-steering pump (did I forget anything?). ANY of those could cause a whine noise, but that noise should change in pitch (frequency) with a change in RPM. If it was a noise caused by part of the emissions system, that also would change with a change in engine RPM.
I really think that it would be a good thing if you want to avoid a flatbed trip to a mechanic, if you pulled the engine cover behind the seats and tried to localize the location of the noise. Without that - any ideas we might have (or someone on FB) is just a WAG..
I first noticed it a few days ago upon first start. It seemed to go away over my only 2 mile drive. Same thing getting back in the car to drive home. However, yesterday it whined the entire time though I feel it lessened during the drive.
A couple weeks ago I had the oil changed and the shop said I needed a new battery because the battery was seven years old and it was taking longer to crank than it should. I noticed the past few days it was taking longer and longer to crank and so I put in the new battery. After doing so is when I took the video I posted where the whine is much much louder. I have not driven it since I took the video as I don’t want to cause any additional damage.
Two additional points:
1. the car only has 67,000 miles on it.
2. I live in Southwest Mississippi and we have been in the hundreds for most of the past several weeks. On multiple days the heat index has been near 113-115 so we have had really high temperatures.
@deilenberger
Don, you bring up two points which I want to put my spin on.
1) You mention the cooling fan, and hardly ever hearing it run. During my ownership of a 996, I noticed that it would run far more frequently than my 987.1, even after pulling into my garage with a hot engine it would run after the engine was shut down, and even cycle occasionally while it reached a temperature to satisfy the sensor, then kick back on when the hot engine raised the temp in the engine compartment. In my 987, it always shuts off immediately when I shut the ignition off. But, like the other day when I shut the engine off and the fan turned off and I went back out to the garage to check tire pressures a few minutes later, the minute I turned the key to ‘ACC’ the fan ran again, apparently the sensor was reading hot enough to call for the fan again. Strange behavior, but seemingly normal.
2) I like how you referenced PORT and STARBOARD, sailing terms, when delineating a specific side of the vehicle. We usually hear people use ‘drivers side’ or ‘passengers side’, which is typically clear enough, but with posters from around the globe that requires the mention of left side drive or right side drive. And some even say “left side-from the front of the car” or “left side-from the drivers seat”. PORT and STARBOARD seems to take away any confusion, but for non-boaters it only adds more. Of course it’s a minor gripe, but I like your take of looking at the vehicle from a boaters perspective.
