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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.
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 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?
Originally Posted by dgmark
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.
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.
Originally Posted by Quadcammer
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?
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.
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.
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.
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.
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.
Originally Posted by dgmark
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.
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?
Originally Posted by cds72911
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).
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.
Originally Posted by Splitting Atoms
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.
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:
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.
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.
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.
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.
07-10-2018, 12:40 AM
Flywheel damaged by CPS?
