Chirping noise from transmission / flywheel
05-02-2013, 12:15 PM
#1
Rennlist Member
Thread Starter
Chirping noise from transmission / flywheel
Car: 996 GT3. 26K miles. All original. All stock.
The engine was dropped, coolant pipes were welded, and rear main seal was changed by me.
I installed a 997 GT3 RMS that ended up leaking. I then paid a shop to fix it, and they did another 997 GT3 rear main seal install that also leaked. Finally the shop did it again, but put in a 996 Turbo rear main seal. It is now leak free, but once the car was delivered the noise below began 1 day afterwards.
The chirp seems to be coming from the bell housing area. The video only shows the top view of it as under the car, the ruckus from the exhaust drowns out the noise picked up by the phone's recording abilities. An ear up on the bell housing makes it seem louder.
There's no noticeable loss of performance, or idle quality. The noise doesn't appear until the car is up at operating temperature.
The shop said it was a pilot bearing. The noise doesn't change pitch, frequency, speed, tone, or volume if the car is in gear or in neutral. If the pilot is failing, then when the clutch is in, the transmission shaft would not be spinning the same speed as the fly wheel, and the bearing would be taking up this difference. When in gear and spinning (on the shop's lift), the pilot would be spinning with everything else and it's "bearing" effect would be null, and the noise would disappear. The noise is unaffected by these tests. The noise remains, and even in gear with RPMs increasing, the noise is there until the exhaust drowns it out.
The clutch pedal also was used to narrow down the possibility of it being the throw out bearing. No efforts in clutch pedal were able to add / remove from the repetitive chirp at any speed, any gear, any load.
My next location to look could be the vacuum lines on the back of the manifold. Would that make for this noise if there was a leak? I would think it would be more of a hiss, and I don't know what would make it pulsate.
Is there anything within the transmission, such as a pump or within the original (good condition) dual mass flywheel that would cause this? A bad spring on the clutch disc or within the dual mass? Even as the RPMs increase the noise's pulsating frequency does NOT increase to match. It remains it's consistent rhythm.
Any ideas?
EDITED: More descriptive title.
The engine was dropped, coolant pipes were welded, and rear main seal was changed by me.
I installed a 997 GT3 RMS that ended up leaking. I then paid a shop to fix it, and they did another 997 GT3 rear main seal install that also leaked. Finally the shop did it again, but put in a 996 Turbo rear main seal. It is now leak free, but once the car was delivered the noise below began 1 day afterwards.
The chirp seems to be coming from the bell housing area. The video only shows the top view of it as under the car, the ruckus from the exhaust drowns out the noise picked up by the phone's recording abilities. An ear up on the bell housing makes it seem louder.
There's no noticeable loss of performance, or idle quality. The noise doesn't appear until the car is up at operating temperature.
The shop said it was a pilot bearing. The noise doesn't change pitch, frequency, speed, tone, or volume if the car is in gear or in neutral. If the pilot is failing, then when the clutch is in, the transmission shaft would not be spinning the same speed as the fly wheel, and the bearing would be taking up this difference. When in gear and spinning (on the shop's lift), the pilot would be spinning with everything else and it's "bearing" effect would be null, and the noise would disappear. The noise is unaffected by these tests. The noise remains, and even in gear with RPMs increasing, the noise is there until the exhaust drowns it out.
The clutch pedal also was used to narrow down the possibility of it being the throw out bearing. No efforts in clutch pedal were able to add / remove from the repetitive chirp at any speed, any gear, any load.
My next location to look could be the vacuum lines on the back of the manifold. Would that make for this noise if there was a leak? I would think it would be more of a hiss, and I don't know what would make it pulsate.
Is there anything within the transmission, such as a pump or within the original (good condition) dual mass flywheel that would cause this? A bad spring on the clutch disc or within the dual mass? Even as the RPMs increase the noise's pulsating frequency does NOT increase to match. It remains it's consistent rhythm.
Any ideas?
EDITED: More descriptive title.
Last edited by loworbitsi; 05-02-2013 at 03:49 PM.
05-02-2013, 01:47 PM
#4
Rennlist Member
Thread Starter
Just laid under the car with flash light and camera phone. It's certainly the loudest coming out of the flywheel inspection port that's directly below the starter. Clearly something within the clutch / flywheel assembly.
What would a RMS install do to the removal / re-installation of the OEM flywheel that hasn't been changed? Tolerances are tight in the bell housing up near the starter ring gear and crank case position sensor, but would rubbing make that noise? A bad spring within the dual mass assembly? Are these prone to failing or being damaged during service work?
What would a RMS install do to the removal / re-installation of the OEM flywheel that hasn't been changed? Tolerances are tight in the bell housing up near the starter ring gear and crank case position sensor, but would rubbing make that noise? A bad spring within the dual mass assembly? Are these prone to failing or being damaged during service work?
05-02-2013, 01:58 PM
#5
I believe I have the same issue in my car after having the RMS replaced last year. At work now. Will post video this afternoon... I went nuts trying to figure out what the problem is. Water pump, belt idlers, alternator bearings, chain tensioner. I does not come come on until about 3 or 4 minutes into a cold start. Car has been running fine but very annoying! No other performance issues at all... Just a chirping as you described...
05-02-2013, 02:01 PM
#6
i have the EXACT noise you have since i had crank shaft repaired and remachined heads, ...all belts changed too and lwfw and throw out bearing and clutch new, (thought it might be throw out bearing) alternator new, new water pump, even with stethoscope cant find it....
a reputable engine builder here who builds for rolex porsche series couldnt find it nor could my dealer nor my local race shop in sebring..
here is one thread and wondering whether the noise goes away when you depress clutch...i think mine doesnt and the shop did change the throwout bearing with no change in chirp.
https://rennlist.com/forums/racing-a...g-failure.html
https://rennlist.com/forums/928-foru...-sounds-2.html
mike
7 track days since chirping, car is faster
if you can find out what it is that would be great..
i cant video it now as car is in sebring but in 2 wks i'll try to remember to get a clip
the chirping starts as the car warms up...and gets worse then stabilizes....
mike
a reputable engine builder here who builds for rolex porsche series couldnt find it nor could my dealer nor my local race shop in sebring..
here is one thread and wondering whether the noise goes away when you depress clutch...i think mine doesnt and the shop did change the throwout bearing with no change in chirp.
https://rennlist.com/forums/racing-a...g-failure.html
https://rennlist.com/forums/928-foru...-sounds-2.html
mike
7 track days since chirping, car is faster
if you can find out what it is that would be great..
i cant video it now as car is in sebring but in 2 wks i'll try to remember to get a clip
the chirping starts as the car warms up...and gets worse then stabilizes....
mike
Trending Topics
05-02-2013, 02:19 PM
#8
Rennlist Member
Thread Starter
Original clutch / flywheel / pilot, just the new 996 Turbo RMS inside there. It's the only thing that changed.
My chirp starts out quiet, then gets louder. It gets really loud when the car is being driven hard. You can't hear it when it's in motion, but when you come to a stop light, it echos off the cars beside you.
It makes the same noise whether it's in gear, in neutral, etc. The pilot bearing thread is good info, but I don't think it's the same.
My chirp starts out quiet, then gets louder. It gets really loud when the car is being driven hard. You can't hear it when it's in motion, but when you come to a stop light, it echos off the cars beside you.
It makes the same noise whether it's in gear, in neutral, etc. The pilot bearing thread is good info, but I don't think it's the same.
05-02-2013, 08:00 PM
#13
Just checked my records, I just got a new RMS 999.113.426.40 and a new throw out bearing 950.116.080.08 I have a relatively new clutch installed by the PO before we bought the car. There were no noises until RMS repair. Here's what is sounds like... Work was done in Jul 2011. Done many track days with no problem...
Hopefully the link will work:
http://nicotra4.homeserver.com:8000/...Sound_Diag.mov
Hopefully the link will work:
http://nicotra4.homeserver.com:8000/...Sound_Diag.mov
05-02-2013, 09:58 PM
#14
Rennlist Member
Thread Starter
Thanks for the link, Guru! I can totally hear that same sound ever so faintly in the back ground. It sounds like a lot of the videos that I took (but hadn't uploaded). It HAS to be the same thing.
Wow... that's really actually good feeling to know that you've enjoyed the car and the sound hasn't effected it in any way.
Has it ever gotten quieter or louder since?
Wow... that's really actually good feeling to know that you've enjoyed the car and the sound hasn't effected it in any way.
Has it ever gotten quieter or louder since?
05-02-2013, 10:05 PM
#15
No, the sound has not changed. I figured I will eventually look into it the next time the engine is removed from the car. Just checked my records, work was done 1500 miles ago... Still runs like a bat out of H33l! Just annoying and embarrassing :O