Crankwalk has been a major topic surrounding the EA888 Gen 3 engine through the years, often giving owners anxiety for fear of their beloved engine randomly destroying itself without the courtesy of a suicide note. There have been reports of symptoms masquerading as a failed slave cylinder, but more often than not it seems to come out of the blue. The cause of crankwalk comes down to failure of a thrust washer on the outside of the center main bearing. The thrust washer will spin out of its grove, causing all kinds of internal damage before landing on your oil pan in pieces. See #9 for the location of the bastards:
The super majority of unfortunate earners of the crankwalk badge are typically also owners of manual transmissions, although even more rare, some DSG owners have also reported crankwalk. The reality is a very low percentage of EA888 G3 owners may experience crankwalk, and there is a chance the issue is overblown to some extent as the unfortunate voice their opinions online as a result. Probably the most prominent theory is higher clamping force pressure plates included in aftermarket clutch kits may contribute to access thrust washer wear from the extra load place upon them. This is because when the clutch pedal is depressed the diaphragm spring pushes a load axially on the crank and therefore the poor thrust washer. Remember the transmission input shaft (On the right) is only attached to the clutch disk which contains the friction material:
Though even owners with stock clutches have experienced crankwalk as well, so we know aftermarket clutches are not the only cause of the problem. Remember, even some DSG owners have been effected...both of these cases are extremely rare however. When the engine is assembled, there is a NEW axial clearance specification of 0.07 -> 0.23mm with a wear limit of 0.30mm. I do find it odd that a 0.23mm of axial play is within new spec...which means only .07mm of wear would be enough to exceed the wear limit. Yikes. This makes me wonder if a certain number of newly manufactured engines run close to this higher specification of 0.23mm axial play. At this point it really wouldn't take much to bring these engines out of spec, how much axial play is required before the thrust washer joins spin-city is unknown. Here are the specifications in the manual:
The question I'd like to answer is whether axial clearance can be measured without dropping the oil pan or pulling the engine apart. To make the measurement I removed the passenger side inner liner to gain access to the harmonic damper, which you should clean. Depending on your trim level, you may need to remove washer fluid reservoir as well. Using a dowel rod and hammer give the damper bolt a few good hits to move the crank as far to the driver side as possible:
Take a magnetic dial gauge and position it so it slightly pushes against the bolt like so and zero it:
If you are alone, this is where you'll want to position a video camera and record the dial gauge. You'll want to record it on video so you can review the gauge's movement.
Gently climb into the drivers seat and depress the clutch pedal. Review the video to see the maximum axial movement:
Here you can see for a moment it hit about 0.0025in, or 0.064mm. Repeat this procedure a few times to collect an average.
After seven repeats I averaged 0.0022in, or 0.0559mm. With a maximum measurement of 0.0635mm. As you can see my average is 0.0141mm less than spec. Could that 0.0141mm be taken up by oil film? Maybe...who knows. Is this measurement a good sign? Maybe, I'd probably be more anxious if I read a value greater than 0.30mm. It's possible the input-shaft of the transmission might be preventing a full reading which would make it difficult to discern a real conclusion from the measurement. When the time comes to replace the clutch, I'll be sure to re-measure with the transmission on and off the car to see if there are any differences.
I hope to collect some data across multiple cars to see if anything of use can be gleamed from it. I'd be interested to see what axial movement values other cars measure using this method, especially low and high mileage. Please take care to take measurements as similar to the above as possible. If everyone measures differently (ahh yes, that darn human element) the data would be near useless. If you think this procedure can be improved somehow, let me know so I can re-test and update this thread.
Here is some info about my car which could be relevant:
- 89500 miles when measured
- TTRS Clutch since 40k miles, pretty high clamping force, stage 2 around this time
- Vortex Standard since 80k miles
- Euro Spec 0w-40 oil
- Hasn't seen much track use
- Occasional races in Mexico
- I have a habit of being in neutral at lights (clutch pedal not depressed while waiting) some say this is weird, though this also happens to less the time of load on the thrust washer
- Always let oil temp reach at least 170f before burying the throttle
- Cold starts under 32f
- High RPM when cold (Remain at <3k rpm until oil temp is >170f)
- Lots of stop and go driving in traffic
- Primarily city driving
- Aftermarket clutch
- Sitting at stop lights with the clutch depressed
- Repeated hard shifting at the track
- Wrong oil
- Long oil changer intervals