In my 86 190D 2.5 NA I bypassed the fuel thermostat. I first tried to repair the thermostat with the o ring, but it wouldn't stop leaking maybe it has a hairline crack in the plastic elbow. I sure couldn't find any reason for it to leak. Any way after bypassing it no leaks what so ever.

My question dose anyone know what the down fall of leaving it bypassed is?

One thing I did notice is sometimes when I stop and put in park the idle goes up to about 1k-1200 rpm. This could just be sticking linkage though. I am going to put some pb on the linkage and see if it happens again.

In this forum the guy says it is ok I would just like to know if anyone has done it with non-biodiesel.
http://mercedes-190.co.uk/topic/224886/1/