Would fuel temp at 80C+ effect the IP internally?? (o-rings and other delicate bits in addition to the ongoing ULSD effects).

Why ask this question? I've just removed the fuel thermostat because it leaks and considering either a)direct run from prefilter to lift pump or b)prefilter to the heating circuit then to the lift pump. I do have a block heater installed(IDK if it works). Glow plugs work AFAIK. Now that I have the blower motor working I do plan on enjoying heat this winter...We did get a pretty cold winter last year but on average winters in Philly arent too bad and winter blend 'should' not gel until -15F.

Im thinking that I can just do a) and not worry about it. OTH should Philly get another cold winter, I'd like to be able to do b). Looking at the FSM, This circuit is intended to heat the fuel and make starting in cold weather easier/smoother. The fuel thermostat closes and redirects the flow away from the heating circuit and directly to the lift pump at 25C. With no thermostat i.e b), then the coolant temp would= engine temp = 80C+, which = fuel temp the lift pump/IP would be getting. If its that cold, I will be running the heater whenever driving

NOTE: Little bit of lite reading on effect of temp/pressure to diesel viscosity:approx 25C is the temp point with the most change in viscosity. Fuel #3 comes the closest to what I typically run: Diesel+PS Cetane boost.

http://www.mdpi.com/2227-9717/1/2/30/pdf)