[Vwdiesel] Rabbit down on power/ mpg

[Scott Alexander]

I'm digging into my '82 Rabbit Diesel for a number of things.  See  
below for a more complete description, but I have the components in  
front of the injection pump pulled off and will pull the steering rack  
shortly.

When I first got the car running after I bought it, the mpg started to  
fall and it's now in the low 30s.  At the same time, a friend who  
occasionally drove a friend's when it was new believes that this one  
is down on power.  It is capable of producing a black cloud out the  
back.  We checked the compression before getting it running and  
compression was within spec.  We also set the timing on the fuel  
pump.  The valve clearance has not been checked although we're not  
hearing/ seeing any signs of valves incorrectly set.

Since everything is pretty much opened up, I'm trying to figure out if  
there's some deeper work that I should do now.  My friend suggests  
that the rings may be tired.  (He also points out that the oil turns  
black very quickly.)  Since I fear the injection pump ;), I'm  
wondering if it's worth having that rebuilt.  I also have a spare that  
was supposed to be good when pulled that I could swap in as a  
comparison point.  Of course, we're also at the point where it would  
be easier than normal to do things like run another compression check.

Any suggestions on where to look and one to try next?

(One of my A/C mounting ears broke, so I've been pulling everything  
off the front of the engine so as to replace the compressor.  As long  
as I'm in there, I'm swapping out the power steering rack for a manual  
rack.  The manual rack seems to work pretty well on these cars and I'm  
looking forward to not having to work around power steering hoses and  
pumps and stuff in the future.)

thanks,
Scott Alexander
Warren, NJ