Go Back   986 Forum - for Porsche Boxster & Cayman Owners > Porsche Boxster & Cayman Forums > Boxster General Discussions

Reply
 
LinkBack Thread Tools Display Modes
Old 03-07-2015, 01:40 PM   #1
Registered User
 
Join Date: Jan 2015
Location: CT
Posts: 24
Lightbulb 03 S knocking at idle (video)

I searched the forum and it seems that the flywheel may be the culprit, but wanted to post this video to get feedback. The car makes this rattling/knocking sound when warm and only if the clutch is not pressed in.

Any insight would be greatly appreciated.


https://drive.google.com/folderview?id=0B931HkiUarNMfjE1TzBIb09kU1J1aGpRZkp GQWdkWGtHQW9tcnE5MHB1NktZSjVORElHMlU&usp=sharing


Last edited by Ryan986; 03-07-2015 at 01:45 PM.
Ryan986 is offline   Reply With Quote
Old 03-07-2015, 01:49 PM   #2
Registered User
 
Box4two's Avatar
 
Join Date: Jun 2014
Location: Whitby ontario
Posts: 126
Garage
if it goes away when you depress the clutch sounds like a throw out bearing, but kinda loud.
__________________
Previous 2 seaters:
1975 Triumph TR7
1979 Fiat X19
1977 Lotus Esprit
Honey it's an investment!
Box4two is offline   Reply With Quote
Old 03-07-2015, 01:53 PM   #3
Registered User
 
Join Date: Jan 2015
Location: CT
Posts: 24
Quote:
Originally Posted by Box4two View Post
if it goes away when you depress the clutch sounds like a throw out bearing, but kinda loud.
throw out bearing? how does that end up going? I thought it would be a throwout bearing only if the clutch was engaged.

Last edited by Ryan986; 03-07-2015 at 02:17 PM.
Ryan986 is offline   Reply With Quote
Old 03-07-2015, 04:07 PM   #4
Registered User
 
Join Date: Jan 2015
Location: CT
Posts: 24
I watched this youtube video (skip to 1min 5seconds) after the install of a new flywheel, and this guys is making the same noise. Can anyone shed some light on this?

https://www.youtube.com/watch?v=UgsTu1SpEhQ
Ryan986 is offline   Reply With Quote
Old 03-07-2015, 05:37 PM   #5
Need For Speed
 
KRAM36's Avatar
 
Join Date: Feb 2013
Location: Funville
Posts: 2,112
Garage
Quote:
Originally Posted by Ryan986 View Post
I watched this youtube video (skip to 1min 5seconds) after the install of a new flywheel, and this guys is making the same noise. Can anyone shed some light on this?

https://www.youtube.com/watch?v=UgsTu1SpEhQ
His lightweight flywheel is probably out of balance and getting ready to destroy his motor.

3.4 996 Engine upgrade
__________________
2003 Boxster S
| 987 Air Box | K&N Air Filter | 76mm Intake Pipe| 996 76mm TB | 997 Distribution T | Secondary Cat Delete Pipes | Borla Muffler | NHP 200 Cell Exhaust Headers |
KRAM36 is offline   Reply With Quote
Old 03-09-2015, 04:45 AM   #6
Registered User
 
Join Date: Jan 2015
Location: CT
Posts: 24
Just stopped by my local indy and he said that it definetly is not the flywheel, and that its either the transmission ($6K) or the clutch & pressure plate ($2.6k). Does this sound right?
Ryan986 is offline   Reply With Quote
Old 03-09-2015, 06:40 AM   #7
Registered Boxster abuser
 
healthservices's Avatar
 
Join Date: Oct 2011
Location: socal
Posts: 1,014
Why would you think flywheel? Did you just change to a lightweight flywheel?
healthservices is offline   Reply With Quote
Old 03-09-2015, 07:27 AM   #8
Registered User
 
Join Date: Jun 2014
Location: LB, Germany
Posts: 1,350
Hi Ryan986,

what mileage does the car have?
When was clutch and flywheel changed last time? (if yes, at what mileage? and which parts where changed?)
Does the car have a stock flywheel and clutch, or does it have non OEM clutch modifications.
Which manual transmission does the car have? 5-speed, 6-speed?

You've said that the sound only appears when engine/transmission is warm and only if the clutch is not pressed in.

So when the engine is cold, there is no noise?
Smallblock454 is offline   Reply With Quote
Old 03-09-2015, 09:42 AM   #9
Registered User
 
Join Date: Jan 2015
Location: CT
Posts: 24
Quote:
Originally Posted by Smallblock454 View Post
Hi Ryan986,

what mileage does the car have?
When was clutch and flywheel changed last time? (if yes, at what mileage? and which parts where changed?)
Does the car have a stock flywheel and clutch, or does it have non OEM clutch modifications.
Which manual transmission does the car have? 5-speed, 6-speed?

You've said that the sound only appears when engine/transmission is warm and only if the clutch is not pressed in.

So when the engine is cold, there is no noise?
mileage is 130k. Clutch and flywheel were done at 68k. 6 speed manual. its quite when its cold, but once warmed up, is pretty pronounced. when I drove it this morning it was unnoticeable until the car reached normal running temperature. If you try to put it in gear (gently) without pressing the clutch it becomes pronounced as well. Im now thinking its a pressure plate or something in the clutch assembly, hopefully not the tranny.
Ryan986 is offline   Reply With Quote
Old 03-09-2015, 10:16 AM   #10
Registered User
 
Join Date: Jan 2015
Location: CT
Posts: 24
Update: I contacted the Owner previous to the one i bought it from, as the owner i bought it from only had it for a few hundred miles. He advised that he was aware of the sound and was told it was due to the light weight flywheel that was installed. Still seems really loud though.
Ryan986 is offline   Reply With Quote
Old 03-09-2015, 10:47 AM   #11
Registered User
 
Join Date: Jun 2014
Location: LB, Germany
Posts: 1,350
Hello Ryan986,

even a one mass flywheel should not make that sound. There are some disadvantages of one mass flywheels concerning the mass balancing of the engine. I'm pretty shure the noise isn't caused by the one mass flywheel.

When i first heard the sound in your video i thought this is a bearing piston rod failure. But that would be allways there.

Because it only comes up when the engine/transmission is warmed up i would have said release bearing, or transmission input shaft failure.

Concerning the mileage it is possible that the clutch is worn out now. But i've never heard such sounds from a defective flywheel, or clutch components when the clutch is not pressed and car is in neutral.

To be honest i would recommend to bring the car to a workshop as soon as possible and do not drive it any longer. If it is the components i think you'll cause addidtional damage to the clutch and transmission when drinving it.
Smallblock454 is offline   Reply With Quote
Old 03-09-2015, 12:52 PM   #12
Registered User
 
Join Date: May 2014
Location: S.California
Posts: 2,012
Considering the money potentially involved, I suggest a little investment in diagnosis equipment. I use an electronic "Engine Ear" and an old stereoscope. Or even a long screwdriver. CAREFUL !
It is a fairly reliable way of at least locating the source of the noise. That may not seem very helpful until you start contemplating dismantling the engine or transmission to find what a stethoscope would have told you?
It may be as simple as the flywheel/crankshaft bolts have come loose - they should have been replaced with new at the DMF+clutch change.Pressure plate bolts?
Meanwhile, do some research on LWFW vs DMF. The key question is "how are you dealing with harmonic(not dynamic) imbalance?" Some are lucky with the LWFW, others loose and engine. Search for the gory details.
Let us know what you find?
Gelbster is offline   Reply With Quote
Old 03-09-2015, 01:00 PM   #13
Registered User
 
woodsman's Avatar
 
Join Date: Feb 2013
Location: Land of naught
Posts: 1,302
It sounds like the symptoms of a LTW flywheel . I had one in my Boxster. Do the revs drop a little too fast in between regular/slow shifts ?Have a listen to the gearbox. It should be obvious if it's coming from the trans or not.
__________________
Death is certain, life is not.
woodsman is offline   Reply With Quote
Old 03-09-2015, 03:06 PM   #14
Registered User
 
heymanwatchthis's Avatar
 
Join Date: Jul 2013
Location: Asheville, NC
Posts: 102
My '01S does the same thing, but not nearly as loud. Can barely hear it, but is definitely there when the car is hot and idling with clutch out.

Best of luck, hope it is no big deal. Please share what you find out.
__________________
'01 986S: LN IMS, PedroBar, PSS9 coil-overs, underdrive pulley, 997 short shift, GT3 console delete, Crios muffler mod
heymanwatchthis is offline   Reply With Quote
Old 03-09-2015, 10:30 PM   #15
Registered User
 
Join Date: May 2011
Location: QLD.Australia
Posts: 3
Just read this Thread and as an very old ex Volks wagon mechanic in that time now being lucky enough to live in Australia owning a 2002 2.7boxster my answer to your noise would be the front bearing of the transmission mai shaft because by depressing the clutch its stopping the shaft from turning By the way my Boxster is absolutely perfect it always frighten me to read some of this threads but a lot to learn as well done 78.000 km with no major props at all I think they are very good cars loving it this is my first thread since 3 years keep up the good work cheers Werner
werner Uhlich is offline   Reply With Quote
Old 03-10-2015, 08:10 AM   #16
Registered User
 
Join Date: Jan 2015
Location: CT
Posts: 24
Guys at the shop pulled the tranny out. Clutch looks good, pressure plate looks good, and there is a lightweight flywheel installed. They are swapping it back to the dual mass fly, changing out the IMS, and doing a new rear seal. Car should be ready Wednesday. Hopefully this is the fix.
Ryan986 is offline   Reply With Quote
Old 03-10-2015, 08:36 AM   #17
Registered Boxster abuser
 
healthservices's Avatar
 
Join Date: Oct 2011
Location: socal
Posts: 1,014
Boy if it is due to the flywheel I would say it is chain slap then. not enough inertia to keep the chains tight
healthservices is offline   Reply With Quote
Old 03-12-2015, 04:21 AM   #18
Registered User
 
Join Date: Jan 2015
Location: CT
Posts: 24
Final Update:

New IMS, New Clutch, New Dual Mass flywheel, New RMS and $2900...the noise has stopped.

My car feels like it has been neutered going back to the OEM flywheel though
Ryan986 is offline   Reply With Quote
Old 03-12-2015, 10:05 AM   #19
Registered User
 
woodsman's Avatar
 
Join Date: Feb 2013
Location: Land of naught
Posts: 1,302
Quote:
Originally Posted by healthservices View Post
Boy if it is due to the flywheel I would say it is chain slap then. not enough inertia to keep the chains tight
It's gear-lash from the trans
__________________
Death is certain, life is not.
woodsman is offline   Reply With Quote
Old 03-12-2015, 10:07 AM   #20
Registered User
 
woodsman's Avatar
 
Join Date: Feb 2013
Location: Land of naught
Posts: 1,302
Quote:
Originally Posted by Ryan986 View Post
Final Update:

New IMS, New Clutch, New Dual Mass flywheel, New RMS and $2900...the noise has stopped.

My car feels like it has been neutered going back to the OEM flywheel though
peace is not free-- congrats you just effectively lost 35 hp

__________________
Death is certain, life is not.
woodsman is offline   Reply With Quote
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On




All times are GMT -8. The time now is 11:30 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2020, vBulletin Solutions, Inc.
Content Relevant URLs by vBSEO 3.6.0
Copyright 2018 Pelican Parts, LLC - Posts may be archived for display on the Pelican Parts Website -    DMCA Registered Agent Contact Page