1988 190D with estimated 150,000 miles (recently acquired).

I spent some time under the hood and took a couple of photos of the fuel delivery system. I'm trying to decode the logic here:

A - supply from tank
B - inline prefilter (?)
C - unknown gadget with lines that loop along the heater hose
D - lines that loop along heater hose
E - fuel pump
F - fuel filter
G - injection pump

What's going on with gadget "C" and what is the loop along the heater hose?

Thanks!

Rich

Attached Thumbnails

   

That's a fuel thermostat. Under certain conditions, fuel will flow through a passage heated by coolant in the cylinder head before getting to the lifting pump. Someone at MB must have known WVO would become popular

Looks like you need a new o-ring or crush washer for the RIV plug.

Sixto
93 300SD 3.0

Unfortunately, it only heats to about 80*f.