Tai-Pan

I know this topic has been disused, and I did a search but could not find a solution.
I have a whine in my 100K 996 C4s 6mt.
It seems to be this exact problem: But that is not my video.

It appeared about 3 weeks ago and has gotten a bit louder in the last week.
I pull the serpentine belt and the sound remained, so I do not suspect any of the accessories. It appears both while stopped (in neutral) and while driving and matches the revs exactly.

Its is far too loud to be considered normal engine noise, even my oblivious wife asked about it.

Any thoughts are appreciated.

Macster

Don't run the engine any more. I hate to be dramatic but that sounds like an IMSB. I hope I'm wrong. But if I'm not all might not be lost. The engine can be salvaged.

But if you run the engine any more the engine can be toast.

Even if it isn't the IMSB that the noise is present with the belt removed is generally not a good thing.

About the only thing I can think of that wouldn't be engine related would be a bad clutch release bearing. 'course, it you tell me the car's a Tip, never mind.

thewheelman

I'm betting it's the SAI pump making the noise. Mine whines occasionally, especially when it's cold in the mornings. It's a fairly common issue with these cars.

I'll probably pull mine soon and relube the bearings. There's a DIY on rennetech.org, I believe.

964polar

Have you checked your power steering fluid level? But then the noise would be easy to connect to steering wheel movement. Sorry, you said the belt was off, never mind, that includes the steering pump.

trendy996

SAI pumps only come on on startup.

DBJoe996

Have to agree with Macster. That is not a normal engine noise and I would not run the engine. Logic dictates that - with the serpentine belt removed you have eliminated all accessories and belt driven components; thus it is something internal to the engine. Sorry for the bad news, but with 100km, and you gave no clue as to previous maintenance, timing chain pads, spun bearing, bad bearing, etc. Would be wise to drain the oil and check for metal particles and cut open your oil filter to inspect for metal fragments. Since the video is your exact problem, perhaps subscribe and see what the OP found or fixed.

fpb111

Shot in the dark - AOS problem?? Sometimes they do Screech, buzz, yodel when the diaphragm goes bad.
Remove the oil fill cap and see if it changes the noise. This is not always a definitive test but it is quick and free.

Macster

Forgot to mention but you need to get the car flat bedded to a qualified/experienced Porsche shop and let an expert listen to the engine.

He will strive to pinpoint where the noise is coming from as quickly as he can.

Knowing from where in the engine -- if it proves to be from the engine -- then helps one better guess at the cause.

I must stress that you should not run the engine any more other than in the presence of and under the supervision or direction of an experienced tech.

While the noise might be from a relatively speaking benign cause it might not be and thus any further running of the engine can just make the situation worse.

There are times when one can attempt to diagnose what may be wrong, there are other times when this is best left to a pro.

This is one of those times best left to a pro. Just to be safe.

Tai-Pan

Ugh. Well, I was hoping to do the IMS when the clutch needed replacing but I guess I will have to suck it up now. [Insert string of cursing].
I really hope this turn out to be something else, but I am afraid this isn't going to be a pleasant conversation with the mechanic.


The AOS was replaced 1000 miles ago by the previous owner.

alpine003

Don't assume things. Have your mechanic do a proper diagnosis and tell YOU what is wrong. You shouldn't be telling HIM what's wrong based on a few posts over the internet.

Tai-Pan

Ha, fair enough. No need to be pessimistic when hope remains alive!

Tai-Pan

Just to update the thread; I took it in to TPWS here in Austin (well respected independent Porsche shop) and they called me and said that they didn't really think the noise was significant. They felt it was most likely a clutch release bearing. Seems odd to me, but I trust their judgment.

The clutch is probably within ~5,000 miles of the end of life so I am having them to do that and the IMS/RMS while they are in there.

I will update later to see if this truly solves the issue.


Amusing side note: Frannie runs the shop and she sounds like a church lady you should getting baking tips from not the kind of women who would have opinions regarding LN Engineering VS. Pelican IMS replacement parts.

fpb111

You should hear the "Tips" she gives after she drops a wrench on her foot. (J K don't know her or the shop)

alpine003

LOL, so once again the paranoia hits again...

Engine whine = possible IMS = don't drive anymore = clutch release bearing

Meanwhile did you or the techs even pull the sump or inspect the oil filter at the least? I mean I don't automatically assume my migrane headache is a brain tumor. But at least if I suspect something isn't right, I at least get a basic diagnosis like an MRI...

KrazyK

Did you notice any change in noise as you depress and release clutch (in neutral of course)? While I agree with the "change IMSB while your in there" theory, I just hate guessing what a problem is.