[bmw] 325is sudden loss of compression?

["Gary I. Appelbaum" <gary@xxxxxxxxxxxxxxxxxxxx>]

Here goes:
It's an '88 325is with 270,000 miles.  Been running great - no problems.
Pulled off interstate highway, and come to a stop - engine drops to idle and
starts running really rough, I mean "really".  Blip the accelerator and the
engine revs up fine.  Hold accelerator down and engine runs smooth at all rpms
above 1500.  Turn off and try restart.  Starter spins, as though it's not
engaging.  But it is!  Cooling fan is turning; engine is turning - fast.  But
it wont start.  Push it and jump start it (5-speed).  Starts no problem.  Still
runs fine at speed.  Get home, turn off, try restart - no go.  Starter spins
engine, fast, but no start.  Try next day on cold engine - the same thing.
 Push start it and take to trusted independent BMW mechanic.

They say all 6 cylinders have zero compression.  They say fuel pressure is good
and injectors are working.  Starter is fine, timing is okay, valves are not too
tight.  Rings are worn.  Put fluid in cylinders and compression comes up, but
only for a few minutes.

How can rings get so worn that there was never a sign of trouble until this?
Why didn't I have even a glint of hard starting prior to suddenly no starting?
How can all 6 cylinders wear all the way down at the same time?
What else can it be?

Please help!

Gary A.
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