Flywheel damaged by CPS?

2003 C4S MT, 92k miles. Hoping to have someone convince me my flywheel's not shot. Here's the chain of events: 1. Drive 3 miles down the road to get dinner, car is running fine, 85 degrees outside. 2. Driving back, half mile 'til home and go I over some railroad tracks. Nothing too severe/bumpy, I drive over them every day (3 - 5MPH). I hear an initial single "clunk" and then a fast paced rattle that is consistent with RPM's. Almost like the sound of a card in the spokes of a bicycle, or a timing chain rattling loudly. My house is literally 20 seconds away so continue on and make it to the garage. 3. As soon as I pull in the car dies. I tried to restart and it starts briefly but then putters away and dies again. 4. I pull out my scanner and get code P0336. I did some reading and find it's likely the crankshaft position sensor. I order part #: 986-606-112-04-M14. 5. Car sits for about two weeks while I wait for the part to come in. Yesterday: 1. I install the new CPS. Upon removal, I find the old CPS got chewed up by the flywheel somehow (see below). I assume this was the "clunk"? Still not sure what the accompanying rattle consistent with the RPM's was though... 2. I fire up the car. Takes a few seconds longer than normal to start but fires up fine and sounds normal. Let it sit there for a few minutes, idling fine, but won't rev past 3k RPM when stationary - that's new! 3. I try to pull away and the car dies after it moves a few inches. Pull out scanner, P0335 faulted. 4. Start car back up, clear codes. Wait a few minutes and scan again, P0335 pending. This evening: 1. Out of curiosity, I disconnect new CPS and try to start engine. Cranks fine, but never starts up. 2. Reset DME by unplugging battery for 30 minutes. Clean pins on CPS connector. Cleaned the ground connection near the CPS bracket, unsure if it's related but what the heck. 3. Start the car up again. Same symptoms as before, idles fine, P0335 pending. Drive a few inches and it dies. It will run indefinitely as long as it's stationary - no rattles or abnormal noises. 4. I read up upon the fragility of the flywheel, remember how the old CPS got chewed up, convince myself when the flywheel came in contact it self destructed and can no longer give a reading to the CPS. Thanks for reading, numbers were the best way I could find to logically lay this all out. If someone presented me this car's symptoms without being there for what originally happened, I'd probably point to the sensor/harness causing P0335. But because of the noise/rattle that occurred first, I'm thinking it was more than that. Also P.O. replaced the clutch along with the IMS/RMS about two years ago. I assume the flywheel was done then too, but I'm not positive. I've put about had 6k miles on since then. What do you think? And how could the flywheel ever even come in contact with the fixed CPS?

Bent teeth will cause the revving problem. I think the only way to check is by scoping the cps output and seeing if the signal/amplitude of each tooth is the same. Or stick a boroscope into the cps hole to see if you can see the bent tooth/teeth. I had a bent tooth and lucky enough to have a couple shop owner friends bend the tooth back to get a good signal. But I think you need to find out how the cps was scored first.

I hate to be the bearer of bad news but unless the flywheel or the trans bell housing bolts loosened up this is a symptom of a bad rear main bearing.

not sure how the starter ring is attached, but it is it possible its somehow gotten loose and flops around enough to hit the cps?

Quotes source posts: 15131707, 15132018, 15132175

I don't have a scope, or access to one, but I might be able to check via the CPS hole. Would I be able to crank the engine by hand and observe the flywheel rotate? Ugh. Well at this point, I'm suppose I'm pretty numb to mechanical failures. Just broke the oil pump gear this past weekend on my 928, and all of my R12 leaked out of my 944. This seems to fit the pattern. So by "rear main bearing" do you mean IMS? That would be massively unfortunate considering it was just replaced not too long ago. That's a great thought, though I'm not sure how to confirm that. It does start fine now with no abnormal noises. I wonder if it's significant that I went from P0336 to P0335 after replacing the CPS.

Yes, turn the crank pulley slowly while looking through the hole with a boroscope or mirror. The CPS can still work with the scoring (did in my case). But you don't exactly know when the damage occurred. Hoping it was damaged when the clutch was installed and not something recent.

The only way that there will be contact between the pickup sensor and the reluctor teeth is if a foreign object damaged the reluctor teeth, "a loose bolt" the flywheel is loose or if the rear crankshaft bearing has failed allowing the crankshaft to walk around.

Was the replacement sensor damaged in the same fashion? I don't think the other poster means the Intermediate Shaft Bearing, I suspect they mean the bearings on the crankshaft. I think the logic is that something must be causing eccentricity in the rotation of the shaft to allow the teeth to move far enough outward to make contact with the crank position sensor. I wonder if a failing center on a dual mass flywheel could separate the two parts enough for the outer hunk of steel (with the teeth on it) to wobble and make contact? That is my guess (but purely a guess).

To hit the CPS, you would need like what... .050" of run out on the crankshaft? Not so sure you've would've been able to run your engine with that much run out, but then again I don't know the clearance between the two. Since the trans needs to come out, you can use a dial indicator to measure the run out.

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I'm thinking the same thing. If you had that much clearance on the crank bearing, it would have a major impact on oil pressure. The RMS would probably also be damaged from the crank wobble and you would be leaking a lot of oil. A failed crank bearing seems unlikely. The first thing I would look at is the dual mass flywheel. There is normally some play with the two pieces of the flywheel held in place by springs with retainers. I have a bad DMF on my F250 right now that I need to replace. The plastic spring retainers are known to disintegrate. The 996 DMFs don't last forever either. Since you can get replacements for around $400 now, it's not too painful to install a new one. Get new bolts with the new flywheel.

Quotes source posts: 15132287, 15132290, 15132292, 15132376

I believe this was recent damage. The P.O. rebuilt the engine during the IMS/RMS replacement and supplied me with his pictures of the process. I can see in one where bellhousing is off that the CPS looked to be free of any marks. See below. Do you think that if the rear crank bearing failed, it could be noticable during stationary idleing? Or only if the car was in motion? ​​​​​​​ ​​​​​​​ No, when I removed the replacement sensor it was undamaged. It had been in the car for about 15 minutes total of idling/stalling when moving. I agree that something is amiss which causing the eccentricity; my guess would be that the slight bump from the railroad tracks, combined with engaging the clutch, dislodged "something" and allowed the flywheel to bump against the CPS. Whatever came off was probably the rattle sound too, otherwise I would think I'd still be hearing it when the car is idling. I will find out when I open up the housing, which sounds like what I'll have to do next. I'm hoping whatever it was that fell off, it's sitting at the bottom. ​​​​​​​ Oil pressure is currently reading normal. Now that you mention the leak, there is a slight leak that I've had for about 6 months. I first noticed it when my car sat on jack stands for about 3 months during my winter suspsension refresh. I had a drop of oil beneath the bellhousing area and on the floor. Very slight, and I assumed it was just from the angle of the car and sitting so long. I snapped a picture of it, see below. Never any drips on the floor when driving it regularly. I can see a few inches below the CPS that since then there's been a wet spot, but I couldn't tell if it's from behind the bellhousing, which I assume means RMS, or up above somewhere - maybe AOS? Here's a few visuals:

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Rotate the engine CLOCKWISE only !!!

Is that engine in the photo from a tiptronic car? I wonder if there's something (a bolt) dropped inside the bell housing and got picked up by the timing teeth of the flywhweel. Seems the easiest is to stick a borescope into the CPS sensor hole and hand rotate the engine (clockwise only) and see if anything obvious. Next step will be to remove the transmission and do visual inspection.

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Nope, manual transmission. Same engine in all pics. And yeah, that's my hope as well. I've got a scope on order. Fingers crossed this was something simple.

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Looks like it has the tiptronic adaptor ring on it (part #14 here ). I also spotted some vacuum connectors that are only for tiptronic cars.

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Pretty sure you are right that the first picture in post #11 is a tiptronic.

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Yeah that's what I thought too. Just found it odd that the OP has a manual trans.

Could the dual mass flywheel have been on its last legs and the jolt finished it off ?? I believe there is a rubber bush integral to its internal workings , if this has failed throwing the sensor ring out of true it could hit the sensor and I bet has done again I'd pull the new one and inspect for damage also !!

Could a clutch cover bolt come loose, then get jammed between the flywheel edge and the casing, going past the CPS and mashing it? You can buy USB boroscope cameras on Amazon real cheap, I'd start there and see what you can find by scoping it.

Thanks for all the feedback, everyone. Truly appreciate all of your insight. My first order of business will be to get a borescope in there to see if I can get a better idea what I'm looking at. Hopefully I find a smoking gun. After that, I will drop the transmission and open up the bellhousing to inspect the flywheel further. I am expecting to find missing/bent teeth. I've been reading up more on the construction of the DMF and it seems plausible that it was a spring/bolt that separated and could have hopefully caused this movement which damaged the CPS. The transmission drop will be uncharted territory, but I found a few how-to's that don't seem too difficult to complete. Please let me know though if you have any recommendations or things to watch for in this process.

The photo showing the rear of the engine shows the Torque convertor intermediate housing for a Tiptronic transmission , its for 2005 997/1 ( not earlier ) as Ahsai has mentioned , so that engine shown in the photo had up to that point in time had a " A 97;01 or a A 97: 31" Tiptronic ( Automatic ) transmission

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Very strange indeed. The car had a replacement engine earlier in its life. Looks they must have adapted the tiptronic engine for this car's usage.

The gap should be 0.0394�. (1mm +/- 0.2mm)

Just drop the trans and forget about scoping as it needs to come out one way or the other...Good luck and take pictures! The trans drop is simple but a little time consuming, just take it slow and be careful.

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Good idea. Might as well save some time on scoping. My 928 is currently occupying my garage bay but hopefully will be finished in about a week (timing belt, waterpump, cam gears, and everything else in that general vicinity), then I can start on this. What do you guys think about the replacement DMF's? Is Luk the way to go?

Luk is the only one that makes them as far as I know. If you buy one in a Sachs box it will have Luk stamped on it. Rockauto sells one labelled Brute Power or something like that, probably a Luk too.

Quotes source post: 15136785

This. You have something banging around in there. You are very lucky the CPS is the only thing that has been damaged. I had the displeasure of seeing what can happen when something gets inside the bell housing and tries to work its way between the flywheel or clutch and the bell housing... things get very expensive. I would not drive this car another inch until this issue is resolved.