[Vwdiesel] RE:Gunked up case, good parts- Clean case, all worn out?

[Libbybapa at wmconnect.com]

I have recently worked on rebuilding two airhead type 4 motors, but this 
paradoxical situation would seem to apply to other engines as well.  Both were 
driven till the motors were toast in the same area/climate- Flagstaff, AZ.  No 
idea how many miles were on them- they weren't running when I bought them and 
had flipped or non functioning odos.  One was a 1.7lL from a '73 bus, one was an 
2.0L from an '81 vanagon.  Both crankcases are virtually the same (breather 
is slightly different, cosmetic, not functionally).  Anyway, the confusing 
issue is that the case on the '73 was all gunked up thick with varnish/sludge- I 
mean really gunked up (tanking didn't come close to getting it clean), but the 
engine internals were beautiful.  The crank was still on the brand new side of 
spec.  The cam was somewhat worn, but not worn out as would be typical.  The 
engine, from the looks of it had not been rebuilt in a long time.  The 
cylinders were worn out, and the crud had grown on fins completely filling them.  Two 
pistons were busted.
  On the other hand, the '81 case was sparkling clean.  No varnish, or 
sludge- I mean pretty to look at.  The internals were attrocious.  The crank was a 
solid 15 thou out of spec on all mains.  I can't think the cam was lifting the 
valves.  The thrust surface was even worn out- very untypical for those cases, 
unlike the beetle.
  Anyone have any explanations/thoughts/comments?  Any similar experiences?  
I would have thought- gunked case=crappy parts/clean case=good parts.  HMMM.
Andrew