Whirring noise on acceleration
#1
Whirring noise on acceleration
Hey gents,
My 2001 996 TT is making a pronounced whirring/humming noise while under acceleration...a noise that seems to change (increase/decrease in pitch) depending upon RPM.
It doesn't make any such noise at idle, nor does it seem to make any noise when pushing in the clutch (coasting at speed) and/or while revving the engine.
Any idea's what this might be? Concerning.
Thanks.
My 2001 996 TT is making a pronounced whirring/humming noise while under acceleration...a noise that seems to change (increase/decrease in pitch) depending upon RPM.
It doesn't make any such noise at idle, nor does it seem to make any noise when pushing in the clutch (coasting at speed) and/or while revving the engine.
Any idea's what this might be? Concerning.
Thanks.
#2
Ok, update...pulled the radio/speaker fuses and as expected, the sound is still there.
A bit more clarification - seems the noise is non existent when driving around town. I only seem to hear it when I'm on the freeway (at speeds where I'm using 4th - 6th gears).
Cruising along in 5th or 6th gear on the freeway, it seems to be the loudest between 2200 and 3000 rpm's. Again, every time I step on the gas ever so slightly (even when not in boost - so not a symptom of the Turbos).
It's just a whirring, whining noise that changes in pitch linearly with RPM's.
A bit more clarification - seems the noise is non existent when driving around town. I only seem to hear it when I'm on the freeway (at speeds where I'm using 4th - 6th gears).
Cruising along in 5th or 6th gear on the freeway, it seems to be the loudest between 2200 and 3000 rpm's. Again, every time I step on the gas ever so slightly (even when not in boost - so not a symptom of the Turbos).
It's just a whirring, whining noise that changes in pitch linearly with RPM's.
#4
Well, my first impression is it is an exhaust leak.
However, I could imagine -- I have a pretty good imagination though -- under throttle the engine's twisting (or the transmission is twisting) (due to a failed engine or transmission mount) and the engine or part of it or the transmission or part of it is contacting something.
However, I could imagine -- I have a pretty good imagination though -- under throttle the engine's twisting (or the transmission is twisting) (due to a failed engine or transmission mount) and the engine or part of it or the transmission or part of it is contacting something.
#6
Well, it's official. My transmission is toast.
How foolish it was to trust Zuluracerx and his "fresh" PPI from BBI.
With an extremely loud kline 3" decat exhaust and the stereo, I didn't hear the transmission noises until after I bought the thing. The noises only became evident with no stereo and after a bit more time, while on the freeway. Couldn't hear it around town.
Moral of the story? Don't trust anyone (no matter how well they check out nor what they say) and get your own PPI done. (DUH)
In the end, people who say they'll "stand by the car should you have any problems"...don't. Instead they accuse you of ruining the transmission by "launching the car", etc. Not the case. I cautiously drove the thing home in 6th gear, to and from the grocery store, to and from cars and coffee (in town) and to and from the Porsche shop to diagnose the noises. That's it. Anyhow, my fault for buying without getting it thoroughly checked.
Anyhow, I'll be happy with the car once the transmission is rebuilt but damn, what a HUGE unexpected expense right out of the gate. Big lesson learned.
Good thing my wife is taking it so well.
How foolish it was to trust Zuluracerx and his "fresh" PPI from BBI.
With an extremely loud kline 3" decat exhaust and the stereo, I didn't hear the transmission noises until after I bought the thing. The noises only became evident with no stereo and after a bit more time, while on the freeway. Couldn't hear it around town.
Moral of the story? Don't trust anyone (no matter how well they check out nor what they say) and get your own PPI done. (DUH)
In the end, people who say they'll "stand by the car should you have any problems"...don't. Instead they accuse you of ruining the transmission by "launching the car", etc. Not the case. I cautiously drove the thing home in 6th gear, to and from the grocery store, to and from cars and coffee (in town) and to and from the Porsche shop to diagnose the noises. That's it. Anyhow, my fault for buying without getting it thoroughly checked.
Anyhow, I'll be happy with the car once the transmission is rebuilt but damn, what a HUGE unexpected expense right out of the gate. Big lesson learned.
Good thing my wife is taking it so well.
Last edited by MotoJB; 03-03-2016 at 11:14 PM.
#7
Too bad it turned out to be the transmission. These are generally pretty durable.
Thanks for the update.
Thanks for the update.
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#9
Here's the latest...input and suggestions welcomed!
"My tech is just wrapping it up.
I’ve heard the main components worn out are the pinion bearings, bearing retaining plate, 2nd gear, 1st/2nd shift sleeve, 3rd/4th fork – we’ll also recommend the synchros.
Someone has been in this box before, 5th gear has been replaced with a stock 993 gear presumably BC the original was worn out. There are steel synchros in 3rd-5th gear positions also. Do you think you’ll want new steel ones again or brass ones for half the cost? Your ring and pinion has some uneven wear but is okay to reuse but not with TON of power.
At a glance this will be much cheaper than buying our gearbox but it’s still going to be an expensive service.
Estimate to follow."
"My tech is just wrapping it up.
I’ve heard the main components worn out are the pinion bearings, bearing retaining plate, 2nd gear, 1st/2nd shift sleeve, 3rd/4th fork – we’ll also recommend the synchros.
Someone has been in this box before, 5th gear has been replaced with a stock 993 gear presumably BC the original was worn out. There are steel synchros in 3rd-5th gear positions also. Do you think you’ll want new steel ones again or brass ones for half the cost? Your ring and pinion has some uneven wear but is okay to reuse but not with TON of power.
At a glance this will be much cheaper than buying our gearbox but it’s still going to be an expensive service.
Estimate to follow."
#12
bummer. zuluraxerx sold you this without disclosing that the trans was toast and about to go? hard time imagining he didn't "know" if so thats really lousy.
cant help you wi any advice on the box as that should be wholly dependent upon your eventual goals for the car. obviously if you're gonna ( down the road? ) "build it out"? then do all ya can now, different ratios steel vs brass g2 bits etc. as all i had to do was replace the pinion bearing and i was in and out as all else looked new ( at 120k + miles )..
sorry you hadda do all this so close to having just bought the car. that had to be unanticipated. ouch.
cant help you wi any advice on the box as that should be wholly dependent upon your eventual goals for the car. obviously if you're gonna ( down the road? ) "build it out"? then do all ya can now, different ratios steel vs brass g2 bits etc. as all i had to do was replace the pinion bearing and i was in and out as all else looked new ( at 120k + miles )..
sorry you hadda do all this so close to having just bought the car. that had to be unanticipated. ouch.
#13
bummer. zuluraxerx sold you this without disclosing that the trans was toast and about to go? hard time imagining he didn't "know" if so thats really lousy.
cant help you wi any advice on the box as that should be wholly dependent upon your eventual goals for the car. obviously if you're gonna ( down the road? ) "build it out"? then do all ya can now, different ratios steel vs brass g2 bits etc. as all i had to do was replace the pinion bearing and i was in and out as all else looked new ( at 120k + miles )..
sorry you hadda do all this so close to having just bought the car. that had to be unanticipated. ouch.
cant help you wi any advice on the box as that should be wholly dependent upon your eventual goals for the car. obviously if you're gonna ( down the road? ) "build it out"? then do all ya can now, different ratios steel vs brass g2 bits etc. as all i had to do was replace the pinion bearing and i was in and out as all else looked new ( at 120k + miles )..
sorry you hadda do all this so close to having just bought the car. that had to be unanticipated. ouch.
Yes, painful. When all is said and done, I could have almost had a nice 997 TT for the money dumped into this one. Oh well.
Anyhow, I'm going to the GT2 spec with all steel bits...expensive but trying to do it right.
Thoughts on the GT2 slave mod?
Thanks again for your help man.
#15
Thanks Jim...after time and a lot of dough, it's back together and doing well.
Sucks I had to spend that much money on the trans out of the gate, that could have gone into suspension and power mods.
Oh well. I got my white 996tt unicorn...and lessons learned.
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