03 S knocking at idle (video) - 986 Forum - The Community for Porsche Boxster & Cayman Owners

Ryan986 · 03-07-2015, 01:40 PM

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

Box4two · 03-07-2015, 01:49 PM

if it goes away when you depress the clutch sounds like a throw out bearing, but kinda loud.

Ryan986 · 03-07-2015, 01:53 PM

Quote:

Originally Posted by Box4two

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.

Ryan986 · 03-07-2015, 04:07 PM

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

KRAM36 · 03-07-2015, 05:37 PM

Quote:

Originally Posted by Ryan986

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

Ryan986 · 03-09-2015, 04:45 AM

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?

healthservices · 03-09-2015, 06:40 AM

Why would you think flywheel? Did you just change to a lightweight flywheel?

Smallblock454 · 03-09-2015, 07:27 AM

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?

Ryan986 · 03-09-2015, 09:42 AM

Quote:

Originally Posted by Smallblock454

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 · 03-09-2015, 10:16 AM

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.

Smallblock454 · 03-09-2015, 10:47 AM

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.

Gelbster · 03-09-2015, 12:52 PM

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?

woodsman · 03-09-2015, 01:00 PM

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.

heymanwatchthis · 03-09-2015, 03:06 PM

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.

werner Uhlich · 03-09-2015, 10:30 PM

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

Ryan986 · 03-10-2015, 08:10 AM

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.

healthservices · 03-10-2015, 08:36 AM

Boy if it is due to the flywheel I would say it is chain slap then. not enough inertia to keep the chains tight

Ryan986 · 03-12-2015, 04:21 AM

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 :ah:

woodsman · 03-12-2015, 10:05 AM

Quote:

Originally Posted by healthservices

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

woodsman · 03-12-2015, 10:07 AM

Quote:

Originally Posted by Ryan986

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 :ah:

peace is not free-- congrats you just effectively lost 35 hp