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YOUR RESEARCHEngine whine at 3-3.5k rpm
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Replace 1000 miles ago
Performed · outcome unconfirmed
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Leading evidence: 'Replace 1000 miles ago' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, the most frequently mentioned possible cause is 'wrong word' (1 discussions; 0 report identifying it and 1 suggest it). The most frequently discussed action is 'Replace 1000 miles ago' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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Performed · outcome unconfirmed · Original poster
Altenator has been replaced now with a brand new 997 alternator.
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Performed · outcome unconfirmed · Original poster
AND there was a similar sound at 5k before I changed the alternator.
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Performed · outcome unconfirmed · Original poster
I ran the car at idle, rev'd to 3k, and think I can just about hear it.
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No difference over bumps, nothing to do with road noise.
I noticed an airplane like turbine whine will driving at around 4-5k rpm, I was having electrical issues and thought maybe it was related to the alternator. Altenator has been replaced now with a brand new 997 alternator. No more electrical issues, but now the whine seems more pronounced and at 3-3.5k.
It only seems to occur when the car is in gear, but
not related to speed. If i rev the engine with clutch in i dont hear it. I had wife rev engine to 3.5k while i stood at rear with engine lid open, and also didn't hear it. (so it's also not the wife 😝
-> Not to above, I DO hear it when coasting along and reving engine in neutral. I do NOT hear it when standing at back of engine - so that's odd.
i did remove the alternator three or four times (at first i thought it was the voltage regulator) and thought maybe the belt was getting over stretched or maybe a belt tensioner pulley was getting worn out, but then i would hear the noise at neutral, right?
i'm at all loss of how to best figure out what the noise is, and now it's all i can focus on. i'm going to try and record it tomorrow, but not sure how much the phone mic will pick up.
any guesses??
Yup spent morning reading about pinion issues. Can't seem to find an audio recording of one failing through.
Will go for a run today and see if i can record it. Just so odd it changed with the new alternator. Half tempted to put the old one back in (yet again) and see if noise changes...
The 968 guys will be really familiar with pinion bearing issues, it was a design flaw with the 6MT box in that car. Maybe check out that forum to see if you can find some audio. Jet engine on the highway is usual descriptor.
Dont panic, Getrag tranny's are infamous for 5th and 6th gear wine..
Both my BMW's did it from new.. I drove a ford F30 with a Getrag and it had the same high pitched whine in 5th..
But yes 996 do have a pinion bearing weakness..
Ok so turns out i DO hear the sound when rolling along and revving the engine at neutral. It's also not a very loud sound, and def not jet engine loud. It starts at 3k and increases to 3.5k loudest then gets a bit lost in the other noises.
Here's an almost impossible to hear recording of it, it's that whine in background.
Doubt that�s a pinion bearing.
Given that you�re only hearing it in the cabin, I am wondering if you�re getting electrical interference with your stereo from the new alternator. Have you tried running the engine with the belt off?
The stereo is removed, the speakers are hard wired (from an after market deck) to no where.
I havnt removed the belt, but can try. But i couldnt hear the noise in the rear, but I can try again.
Part of me thinks you shouldn�t even worry about this noise. I�ve heard noises come and go and then return in my car, and I pretend it doesn�t matter. Then five years go by and nothing happens.
That seems to be the sentiment, but it's hard when it's so "there" at exactly 3k RPMs. AND there was a similar sound at 5k before I changed the alternator. I'm sure it's nothing, but my obessive ears can't help it!
I ran the car at idle, rev'd to 3k, and think I can just about hear it. But it's so faint and seems more prevelent at speed. I then took the belt off, and tried again, and it honestly sounds the same... but the sound is so faint i might just be making it up in my head.
Prob just need to fix the radio and turn it up
So again went out yesterday and the sound is very clear at 3k+ rpm. Its not really a whine, more of a high pitched sound. If I press in the clutch it goes away, but if i rev with clutch while moving in it comes back. If I rev while sitting stopped I dont hear it.
What could it be??
Still trying to figure this one out. Top up, I can hardly hear it. Top down, it's so distinct. Starts at 3,000rpm and is the most pronoucned at 3400-3600rpm. Driving along at 50mph on an open road I can rev the engine up and down and hear it. Press clutch in and rev engine and it sounds exactly the same. Come to a stop and rev the engine, can't hear it at all. Like MAYBE I hear something but basically nada.
I went from a 996 alternator to a brand new 997 alternator. I don't think the prior alternator had a clutched pully, but this new one does. Could that have anything to do with it? The problem is I can't hear the noise unless I drive the car, and I can't take the belt off and drive the car.... arrgggg
You and I are kindred spirits. Im also pretty obsessive about noises and I also have a whine on my car, at exactly 2600, which has been driving me nuts. I have some thoughts on your situation but I�m curious, is this car new to you? Is the noise new? And what mods are on the car (Heimholtz delete, high flow cars, gundo mod, aftermarket exhaust)?
EDIT: I have some audio for you:
https://youtube.com/shorts/iWJGhrbbAg8?si=gEwKh5a_Um4xrDvf
Ignore the video, I had to hold the phone to the windshield to cut out the wind noise.
I hear the same higher-order resonance as in your audio. Fainter, but there.
I asked about mods because I think anything that changes the stock intake/exhaust dynamic almost by default will produce these harmonic overtones. They are inherent in the design of the 5 chain engines, and my theory is that the stock setup was designed to cancel out the overtones. Aftermarket, different story. So some cars with mods will have accentuated sounds at 2600 and some will have it at 3500, depending on the mod and how it impacts the resonance. Same thing can happen with aging stock cats or mufflers.
Anyway, that�s my theory. I had a factory trained tech of 40 years listen to my car, he said �sounds fine.�
no mods. totally stock. had the car just about a year. the sound def started after swapping a failing alternator for a new one. i really dont want to swap them back just to see if the noise goes away, but i'm about to get to that point
i drive it pretty zestly on canyon roads, and all i can hear now while zipping through a windy road is that dang noise
OK, maybe it is the alternator. Have you put a mechanic's stethoscope on it? If it's the alternator, it would be very obvious. Much easier than changing it back.
I have not. Will pick one up at Harbor freight today and give it a try. I just don't understand why revving the engine while coasting makes the sound so obvious. But when coming to stop the sound is almost impossible to hear, and I feel like I'm just imagining it is there.
When you installed the alternator did you lower the engine at all for access?
Or, are your rear engine mounts old?
Or is your trans mount original?
These engines have a lot of mechanical noise. If a mount is bad or misaligned, certain frequencies can be transmitted to the cabin or cause other parts on the car to vibrate causing noise.
No, you don't need to drop the engine for Alternator.
Engine mounts I replaced 1000 miles ago
Trans Mounts are original (to my knowledge)
The sound is a definitely wheeeeEeEeEeEeEEeEEeEEeEEEEEEEE noise. "Whine" was probably the wrong word. I'll record it again next time.
Going to go hand spin everything everything connected to a belt again to see if anything else is loose.
I know the tensioner pulleys should NOT spin freely and should have some resistance when you hand spin them. What about the pulley that is mounted on the side of alternator? It spins freely like a skateboard wheel.
You say it�s a �
wheeeeEeEeEeEeEEeEEeEEeEEEEEEEE
�
sound. Do you notice this while driving over bumps or an undulating highway?
The tensioner wheels should spin without noise or roughness. Rotate them with your hand and see if you can feel any grinding. You could also put a mechanics stethoscope on the center bolt while running to listen to them.
No difference over bumps, nothing to do with road noise. I can be coasting at 50mph, push the clutch in, and rev the engine and the sound is the same as if the clutch is engaged and I'm accelerating.
The lower idler and tensioner spin with no roughness, but they don't spin like skateboard wheels. They turn and stop. I watched some videos where they said that is how they should rotate. Except it didn't cover the idler next to the Alternator, that one spins freely like a skateboard wheel on it's bearing.
Here is video of all the things that rotate (what is the 2nd one with the three bolts that sounds kinda iffy? It feels a little odd when you spin one way, then the other, like there is fluid in there resiting.
You Tube
The second one with the three bolts is the power steering pump. It will have fluid resistance and it will clink when spun back and forth. Yours is normal. The pulley closes the alternator is noisy and sounds dry. If it�s not the source it should be greased (if possible) or replaced soon.
Best things to do is get a stethoscope on these things.
It's a brand new Bosch AL0815N. It's the 150a spec for 997. Has a clutch, which is that extra piece you see. I did a lot of confirming and it's a suitable upgrade over the 120a 996 variant. And its not a reman.
It has a little black plastic dist cap that covers the clutch, but it was squeky when I spun it. So taking it off JUST in case that's the source... but doubtful.
Per the alterantor idler pulley. Should it spin like that. yes will get a stethascope.
This is a source reference. Confirm exact model applicability in the original material.
