997.1 Crawls then stops

In need of help. I parked the car at the mall and returned to it after 2 hours. Went inside, clutch in, gear in neutral, started the car, I heard a loud sound, the engine idled, geared in reverse, the car started to move slowly, then stops as if it is in neutral. in lieu of reverse, i tried first gear with same results: crawls for a couple of feet then stops moving as if engine is in neutral. No noise/grinding when shifting gears. I can start the engine without any noises or issues. The loud bang never happened again. Any ideas? It is a 2007 C4S. One article mentioned it might be a “half shaft”. I just lifted the car and it looks like the CV joints are intact and no visible prior leakage. I can manually spin the rear wheels without difficulty and without noise. When I spin one wheel the other side spins in the other direction. Could it be the clutch, pressure plate, Throw out bearing assembly? If it is the clutch assembly, I would be really be disappointed at the dealer for these units were replaced recently (mileage wise). It was 3+ years ago, but the car was never abused, raced, etc. Thank you

I will check tranny fluid next even though so far no sign of tranny fluid leak.

Drive shafts very likely. You need to crawl under the car and look at where the drive shafts connect to the gearbox. They may be loose and you cannot tell unless you look closely.

Quotes source post: 10167227

The bolts are all in and there are no signs of grease leakage. Would you mind clarifying loose? Is there a physical test I can perform in addition to the visual test. What is super concerning is the LOUD sound that occurred before this issue came about. I mean I was at “park” and just cranked the engine. Yesterday, I did hear a soft intermittent noise while engine is idling. The sound was similar to a tin can being dragged on concrete. I am hoping you are correct about the driveshafts as this would be the least expensive problem compared to clutch or broken transmission problems.

If the bolts are all in, then that is not the problem. I am afraid you have to drop the engine-gearbox to find out what happened. The loud "bang" is concerning.

I may have to pull the tranny out. I am hoping that with the write up on Rennlist, plus my experience dropping the engine/tranny combo of my ‘83Sc, I would be successful. Rusnak quoted about $6k for parts and labor (clutch job). 😮 An independent around $3K. An independent (Porsche only), no quote as he wants to see the car. He did say that he has been getting a bunch of “defective clutch component” work lately. He even pointed one out which was recently done by a dealer.

$3K is a good deal for that clutch job. If you have done SC engine outs, then this is within possibility of your own skills. It is more of a G50 box than a 915 box, and there are more things to disconnect at the top, but the process is the same. I can remove an SC engine in 2 hours, the 996 engine takes me more than a day to pull. You can / should do an SC engine out on jackstands, but the 996 can use a lift.

Thanks you for the push. I will be buying a tranny Jack for this tranny-only pull-out. Sadly, i will be using jack stands similar to the others here: https://rennlist.com/forums/997-forum/823814-replacing-the-clutch-in-a-997-1-here-s-how-i-did-it.html

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I finally learned to drop the tranny. Anyways, am I correct to assume these 2 units aren’t supposed to separate and that the 8 bolts? broke off? Thanks

Back pic

I did more checking on the web today and it looks like this dual mass flywheel is gone. It is not supposed to split in half and when turned, it is supposed to just deflect a few teeth (degrees). Car has about 80K and I am blown away that this is broken.

That flywheel is done. Has there been clutch work done to the car before this? rear main seal, for example?

Before the 60k warranty expired, i had the main seal replaced along with clutch, PP, hydraulic clutch and a few switches

Ah, looks to me like the mechanic stressed the flywheel bolts by using an impact wrench instead of torqueing them to the right values. That is a lazy approach. It is also possible that he did not replace the flywheel bolts as well as using the impact wrench. The stressed bolts could not handle the torque of the engine and … snapped.

I forgot to mention I didn’t have the flywheel replaced as I knew (probably bad assumption) that the flywheel would last over 100k. Would over torquing cause these to break? Btw, the bolts that snapped are the ones from LUK. They hold the 2 pieces together. So it looks like there about 4 others from the various forums who had the 8 bolts snapped. I suspect bad batch of bolts?

This was 5+ years ago: https://www.6speedonline.com/forums/997/317512-catastrophic-flywheel-failure.html