Noise when turning off engine
10-25-2009, 11:55 AM
#1
Instructor
Thread Starter
Noise when turning off engine
So......Thanks in advance!
2008 911 Turbo, just bought, and having a noise that only happens when the car is warm and on turning off. As the engine is turning down, there is a noise that sounds like gears clanking but is pretty loud at the end. About 0.5-1 sec.
Doesnt happen when clutch is pressed and then turned off. And doesnt happen when the car is just turned on in the morning and then turned off. Only after it is warm.
Dealer has already changed DMF and it didnt help and porsche says it is normal. But they still changed out the whole transmission, but still get the noise.........
Any one know what this could be???????
2008 911 Turbo, just bought, and having a noise that only happens when the car is warm and on turning off. As the engine is turning down, there is a noise that sounds like gears clanking but is pretty loud at the end. About 0.5-1 sec.
Doesnt happen when clutch is pressed and then turned off. And doesnt happen when the car is just turned on in the morning and then turned off. Only after it is warm.
Dealer has already changed DMF and it didnt help and porsche says it is normal. But they still changed out the whole transmission, but still get the noise.........
Any one know what this could be???????
10-25-2009, 02:38 PM
#3
Race Director
So......Thanks in advance!
2008 911 Turbo, just bought, and having a noise that only happens when the car is warm and on turning off. As the engine is turning down, there is a noise that sounds like gears clanking but is pretty loud at the end. About 0.5-1 sec.
Doesnt happen when clutch is pressed and then turned off. And doesnt happen when the car is just turned on in the morning and then turned off. Only after it is warm.
Dealer has already changed DMF and it didnt help and porsche says it is normal. But they still changed out the whole transmission, but still get the noise.........
Any one know what this could be???????
2008 911 Turbo, just bought, and having a noise that only happens when the car is warm and on turning off. As the engine is turning down, there is a noise that sounds like gears clanking but is pretty loud at the end. About 0.5-1 sec.
Doesnt happen when clutch is pressed and then turned off. And doesnt happen when the car is just turned on in the morning and then turned off. Only after it is warm.
Dealer has already changed DMF and it didnt help and porsche says it is normal. But they still changed out the whole transmission, but still get the noise.........
Any one know what this could be???????
As for not being present in the morning this also fits: The engine/drivetrain is cold. The engine picks up speed very quickly when started and there is less engine speed variation to cause any rattle and the hardware and fluids being cold are less likely to be affected by the variations in speed anyway. The colder fluids act as vibration dampeners.
As long as there are no other symptoms that suggest an engine, clutch or transmission problem I'd have to say the noise is normal. A bit more pronounced perhaps than in similar cars but normal.
Sincerely,
Macster.
10-26-2009, 09:56 AM
#7
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My WAG is the noise is clutch/tranny rattle. As the engine speed very quickly drops off when engne shut off the inertia of the clutch/flywheel cause the clutch disc to rattle a bit on the input shaft of the transmission. This can cause the constant mesh gear clusters to rattle a bit as well. That the noise is *not* present when the clutch pedal is depressed only reinforces my confidence this is the cause.
As for not being present in the morning this also fits: The engine/drivetrain is cold. The engine picks up speed very quickly when started and there is less engine speed variation to cause any rattle and the hardware and fluids being cold are less likely to be affected by the variations in speed anyway. The colder fluids act as vibration dampeners.
As long as there are no other symptoms that suggest an engine, clutch or transmission problem I'd have to say the noise is normal. A bit more pronounced perhaps than in similar cars but normal.
Sincerely,
Macster.
As for not being present in the morning this also fits: The engine/drivetrain is cold. The engine picks up speed very quickly when started and there is less engine speed variation to cause any rattle and the hardware and fluids being cold are less likely to be affected by the variations in speed anyway. The colder fluids act as vibration dampeners.
As long as there are no other symptoms that suggest an engine, clutch or transmission problem I'd have to say the noise is normal. A bit more pronounced perhaps than in similar cars but normal.
Sincerely,
Macster.
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10-26-2009, 11:41 AM
#8
Rennlist Member
Now I feel bad because my car doesn't make the noise. j/k
10-26-2009, 12:04 PM
#9
Race Director
(Besides, a lighter transmission fluid would be quieter cause it would present less drag and thus keep the shaft and gear sets turning at a steadier speed and thus they would rattle less. But I'm not recommending you use anything but the factory fluid. It makes no sense to perhaps have a quieter transmission at the expense of shortening its operational life. Best thing you can do is to have the fluid changed when it is time, or even a bit sooner.)
(Must point out that I've driven my 02 Boxster 225K miles with factory transmission fluid in it the whole time -- changed several times though -- and I think it would be hard to improve on the factory fluid.)
Try this: with the car nice a warm from a longish drive -- nothing hot and heavy, but the engine and especially the drive train want to be up to full operating temperature -- pull car into someplace quiet and where you can open the door and even get out and walk around the car while engine is idling.
I don't have to do this, I can hear this from inside the cabin with the driver's window down.
Do so and give a listen. You will probably hear some faint rattle or dull low pitched tick that seems to be in time with the engine then it is not in time with the engine.
Back in the car depress the clutch pedal fully. The noise should go away. When you release the pedal the noise most likely will not return, until you move the car again then stop it.
If you hear this rattle this is the the clutch disc moving about on the input shaft a bit or the input shaft rattling the gear sets in the transmission maybe a combination of both.
When you shut the engine off this rattle becomes more pronounced for the split second the engine continues to spin before the engine halts.
Some cars exhibit this symptom/noise and some don't. These 6-speed transmissions are pretty heavy duty -- they have to be to withstand the stress these engines subject them too (in the case of the Turbos AWD drive means very likely there'll be no wheel spin to help soften the stress under hard acceleration) -- and they can rattle a bit after warmed up and with engine at idle.
Now if you feel/hear a clunk upon take off and take off becomes a bit of a pain to do smoothly, this can be due to the flywheel's dual mass mechanism. It has failed. Rare but not unknown. This is not normal and the symptoms if present need to be diagnosed and addressed by a qualified technician.
Sincerely,
Macster.
10-26-2009, 12:31 PM
#10
Instructor
Thread Starter
Thanks Macster....beautiful explanation.
No problems with take off, very smooth.
As far as the noise when on idle, yes I hear it. I havent tried to press the clutch and see if it goes away while idling but will do that. But I get no noise when the clutch is depressed all the way on turning off the car.
Very interesting, I appreciate the elaborate respose Macster!!!!!
No problems with take off, very smooth.
As far as the noise when on idle, yes I hear it. I havent tried to press the clutch and see if it goes away while idling but will do that. But I get no noise when the clutch is depressed all the way on turning off the car.
Very interesting, I appreciate the elaborate respose Macster!!!!!
10-26-2009, 08:10 PM
#11
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I have the exact symptom on my 928Gt . appears to be normal operating noise as I replaced EVERYTHING and the rattle is still there at idle...Live with it! Enjoy the other aspects of the car! (BTW, most of the post C6 Corvettes and Ferraris have various trans rattles)
10-26-2009, 10:20 PM
#12
Seared
Rennlist Member
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Atlas,
While not a 997, my relic ('95 993) has exhibited the same sound for the last four years. To make myself feel better, I simply depress the clutch as I shut the engine down. No noise.
Andreas
While not a 997, my relic ('95 993) has exhibited the same sound for the last four years. To make myself feel better, I simply depress the clutch as I shut the engine down. No noise.
Andreas
10-27-2009, 01:04 AM
#13
Instructor
Thread Starter
LOL.....thats what I have started to do just for my own sanity.
The car has 12,000 mile and the dealer replace the flywheel and then second go around the entire tranny........Boy did they ever enjoy the check they got from Porsche.
$4,000 for flywheel and $10,000 for tranny
The car has 12,000 mile and the dealer replace the flywheel and then second go around the entire tranny........Boy did they ever enjoy the check they got from Porsche.
$4,000 for flywheel and $10,000 for tranny
08-04-2010, 12:55 AM
#14
Rennlist Member
My WAG is the noise is clutch/tranny rattle. As the engine speed very quickly drops off when engne shut off the inertia of the clutch/flywheel cause the clutch disc to rattle a bit on the input shaft of the transmission. This can cause the constant mesh gear clusters to rattle a bit as well. That the noise is *not* present when the clutch pedal is depressed only reinforces my confidence this is the cause.
As for not being present in the morning this also fits: The engine/drivetrain is cold. The engine picks up speed very quickly when started and there is less engine speed variation to cause any rattle and the hardware and fluids being cold are less likely to be affected by the variations in speed anyway. The colder fluids act as vibration dampeners.
As long as there are no other symptoms that suggest an engine, clutch or transmission problem I'd have to say the noise is normal. A bit more pronounced perhaps than in similar cars but normal.
Sincerely,
Macster.
As for not being present in the morning this also fits: The engine/drivetrain is cold. The engine picks up speed very quickly when started and there is less engine speed variation to cause any rattle and the hardware and fluids being cold are less likely to be affected by the variations in speed anyway. The colder fluids act as vibration dampeners.
As long as there are no other symptoms that suggest an engine, clutch or transmission problem I'd have to say the noise is normal. A bit more pronounced perhaps than in similar cars but normal.
Sincerely,
Macster.
Thanks for this diagnosis. I just purchased an '03 Boxster S. It exhibits the same symptoms as the Turbo described above. It's good to know that it is likely just some clutch rattle rather than the IMS!
John Cloutier
08-04-2010, 11:55 AM
#15
Race Director
Enjoy your 03 Boxster S. I've enjoyed -- and continue to enjoy -- the heck out of my 02 Boxster. 234K miles worth. Still runs great. The only thing that keeps me from driving the Boxster as much as I used to is I have an 03 Turbo which understandably demands to be driven and try as I might I can't figure out a way to drive them both at the same time.
Sincerely,
Macster.