Re: Engine will not Crank... Starter spins but does not Engage
The starter spinning is not a very reliable indication of the strength of your batteries. It has to spin the truck over fast enough to get the HPOP to put out about 500 psi in order for the injectors to fire. If during this starting you made a white cloud of diesel out the exhaust and it smells like unburned diesel then the injectors are firing but the glow plugs may not be getting the cylinders hot enough for the compression to ignite the diesel. You can use a jumper cable to bypass the glow plug relay and get juice directly to the glowplugs for about 2 minutes. Then turn it over. If there is no white smoke (unburned diesel) then it may just be the batteries cannot spin the starter fast enough. -5 to -10° is a pretty major stress on the batteries so this may indicate they need replacing.
2002 F350 Lariat CC 4x4 Auto 4.10 DRW, DP-Tuner F5 live tuned stock, quiet, 40dd, 40, 60, 80 tow, 80e and 120r, B&W GN, BrakeSmart, 'pooned tank, tank and pre-pump mods, 2µ Dahl 100 filter, regulated return, BTS dual HPOP, AC singles with EDM 34 lpm nozzles, AIS, H2e, Spearco 6.0 IC, Hypermax 3.5" dp--> MBRP 4" 304SS exhaust, BTS tranny, 203º T-stat, Chevron ELC, coolant filter, Oilguard bypass with Schaeffer 9000, WranglerNW 200 amp alternator & Optima group 31 batteries, Nippon-Denso starter, SPA gauges, SteveRacer mods, Hella 80/100W 9007s, Hella Micro DE foglights, 1000FF driving lights, 220W backup lights, Stancor contactor, Michelin XPS Traction tires, X-Springs, Bilstein shox, custom bumpers but otherwise stock. Nov 30 '99 build engine with 16 K miles, Fluidampr, Comp Cam 910 springs, Melling LPOP and ARP headstuds.