Minor mechanical mystery

[Slavvy 0]

I have an m30b34 out of an e34 on a stand and I decided to replace the rear crank seal. Whip the seal carrier thingy off, and lo and behold it has been violently shaved down on the flywheel side. This was a manual car and the rest of the engine etc were in pretty good condition so I really have no idea how this happens, it's clearly something that happened while it was running (note: the chip at the bottom in the middle is *COUGH* my fault). It almost looks like the flywheel has contacted the alloy and ripped the surface to shreds; but I don't see how that's possible at all.

There's no damage on the block whatsoever, and I've circled in red the places where it's blatently obvious that this isnt just wear and tear or fitting/removal damage. Manual car, dual mass flywheel that seems in decent condition. Any ideas?

[*Glenn* 854]

Crankshaft end thrust bearings are worn.. common fault on most manual motors from that era. They are normaly incorporated into one of the crankshaft main bearings. Either centre or rear main in most motors. Some have incorporated main and thrust. Some have the thrust bearings seperate. Chassis , engine # will tell me what to look for, for you

[Slavvy 0]

Engine number is 42254397.

The thrust bearings appear to be on the center main, however I don't see how it's possible for the crankshaft to move several mm and have the flywheel gouge the seal carrier without damaging the seal or the rest of the block. I can't get it to move back and forth by hand at all, and I imagine with things expanding from heat it'd be even harder

[topless 13]

I have money on Glenn's diagnosis..

[*Glenn* 854]

Has the dual mass flywheel got any evidence of rubbing on the back of it ? We didn't look at that the other day when I checked it for you. If it has can you post up a picture or let me have another look at it. End float in the crank normally causes this. However it may be the dual mass. Is the damage new or old looking ?

Edited January 19, 2010 by *Glenn*

[Slavvy 0]

Has the dual mass flywheel got any evidence of rubbing on the back of it ? We didn't look at that the other day when I checked it for you. If it has can you post up a picture or let me have another look at it. End float in the crank normally causes this. However it may be the dual mass. Is the damage new or old looking ?

Damage looks pretty old but the flywheel does indeed have markings that perfectly correspond with the gouging on the alloy. I'll post a picture later if it's absolutely vital, how can the flywheel cause this? Does it bend or something?

[323e30 0]

Was the car converted from auto to manual at any stage?

If the damage looks old it could be because it was rubbing after an auto to manual conversion, I machined down my flywheel 3mm when i converted mine as it was hitting in the same spot by just a fraction.

Edited January 20, 2010 by 323e30

[Slavvy 0]

Was the car converted from auto to manual at any stage?

If the damage looks old it could be because it was rubbing after an auto to manual conversion, I machined down my flywheel 3mm when i converted mine as it was hitting in the same spot by just a fraction.

Nah, it's a factory manual, I got it with the gearbox still on and it still has what appears to be a factory clutch! The condition of the rest of the motor is extremely good too, like it's been babied for a decade, so I really have no idea why there's so much carnage here.