Whatever you decide I'll echo Dave Barton as in the top hose beyond the T-stat in a heat exchanger system isn't exactly logical. We wanna switch on the output side of the radiator on a heat exchange (radiator) system.
Either control it from some location like the ECU coolant temp sensor as the factory does or output side of the heat exchanger, not in the top hose between the T-stat & radiator...that's not likely to control it very well...
Or push-in switch (if your rad takes that style) or screw in switch on the passenger end-tank as the factory did on the E-fan regina cars tho about the lowest temp switch you can get for the regina E-fan cars is 88-92?C for the push in switch on the rubber bushing as Volvo did with their OEM plastique tanker radiators with that spot for the sensor or plastic plug installed ~86-87+?, I forget?
The way Volvo did it on the regina cars sort of mimics how the bi-metallic spring works to twist the valves in the fan clutch open & shut. Less pro-active, but top of the cold side end tank turns the fan on once the heat exchanger is heat soaked just a little below or approximately at T-stat temp; very logical.
Bottom hose maybe a little wasteful for energy/little lower temp but if you lose half your coolant, it'll probably still gimp home without the sensor being in air, so that's nice? Modern cars if the temp reading gets cooler inexplicably, usually turn the fan on continuous as a fail-safe & throw a code or light/message as well as having a float switch somewhere for a 'coolant loss' warning lamp.
Whether the owner heeds the message(s) (or it's even comprehensible to them?) / pulls off in time or shuts it down in time or not is often another matter?...
On a fleet one mechanic had the bright idea to wire the trucks to shut off (relay kills the coil pack or coil power or ECU FI relay or similar) if the oil pressure switch/sender, coolant level float sensor or one other sensor read low or out of range on something critical. People would cuss out the work truck crapping out/stalling (the smarter of them would open the hood & find the coolant low or no oil on the stick after beating the hell out of the truck or something)...might be hairy mid-intersection or with a wiring fault?, but it saved a lot of money/thousands for in-house maintenance in replacing/rebuilding engines & no one got hurt so far? Bad Old days/low tech solutions... Trucks did small circles/smaller excavation company that kept the old beater trucks a long time/didn't mind the oddball interruption or engine stall vs. paying to replace engines all the time on trucks that didn't get checked on or develeped a sudden oil or coolant leak inexplicably...
I don't blame ya/gotta work with what's expedient (not trying to brag or talk down to ya, want you to succeed in achieving your goals & not waste precious dollars or effort), just surprised there aren't a few trickling in or someone doesn't have a FS thread with all those aforementioned items or from their part out 'known good' w/ a Bosch 100A JY or Denso 100A E-fan 92+ 7/9 alt to go if you don't already have that or better to power it (tho dave Barton ran outta belt pulley traction to turn the alt with the stock 240 V-belts for his gigantic (Mark 8 or similar amp-hungry e-fan setup?).
IDK that the e-fan is 'modern,' plenty of cars & trucks have clutched or hydraulic drive mech fans still...
IDK why anyone would route the power thru the small pulley ~50% efficient alt & back to the fan...sounds less efficient than a good T-static clutch or hydraulic drive setup...
On the 240 anyway, with the dual V-birds (belts), the wrapped area of the alt + WP pulleys adds up the wrapped area on the crank pulley in the triangle. There's *just* enough power to spin the water pump, alt with all the stock accessories & cooling fan mostly locked up on a hot day with everything going, as configured.
Kinda throws it outta balance if you take some of the load off the water pump pulley & pile it onto the alt pulley, no? Something's gotta give?
Unless you have some ace up your sleeve for larger radiator/not that powerful of a fan (which is what Volvo did; larger radiator on e-fan cars (so less fan CFM needed for the same BTU exchange rate vs. the clutch fan & more efficient alt under load at idle speeds, namely), more efficient fan, more efficient alt, alternate belt setup?
Just something to consider...Dbarton went thru all kinds of setups to wind up with ~ the same level of cooling as the good quality made in Japan tropical fan clutch & stock 240T/260 (for the pre 85 sheetmetal) pusher fan was capable of...
Ultimately, even with a giant radiator (like a 3-row V6/V8/Diesel size), even if you use the larger diameter & steeper pitch propeller PRV fan blade & larger clutch hub & really lose your mind & have TONS of cooling air/heat exchanger wise, the red engine, as installed in the 240 chassis will overheat with the A/C on towing in 4th at 80mph at 3500-4000rpm+ blowing 3-10psi of boost at it continuous with the A/C on on a 100 degree day. Why is this? The heater valve works by restriction, unless you drill the Group-A holes & run a bypass style heater valve instead of a block off style valve it's going to climb on the temp gauge over time pulling 3000lbs with a bunch of lumber on the roof continuous.
I went to a bypass style valve. (I mean, you could turn on the furnace/240 heater on a 100 degree day too, but I doubt you'd want to
?)
Effective, but mixed feelings on that, as in, extreme cold, if you don't block heat the engine, you *want* the restriction style heater valve shut off prior to startup for faster warm-up times starting up stone cold w/proper oil & gentle light throttle cruise/gently varying RPM for engine wear in those conditions. Make sense? On a cold day, try timing your light cruise warmup time to OP temp with the heater valve left open vs. shut if you don't believe me. Not everyone is towing under load in the hi desert or doing thunderhill race track at full boost in their outdated Group-A car
...there's a reason the daily driver/factory cars come with a cost & use compromise restriction heater valve & don't have the Group-A holes drilled in the back of the cylinder head...
SCAABS are mostly done, C900s & their transmissions especially,...the brand defacto doesn't exist/no dealer network or inventory or easy way to get parts in your town for the thing in a reasonable amount of time?
If you're a hardcore SAAB-Story-head, you can still keep one going probably, but they mostly all expired by now west coast & are gone off even 99.99% the backwater Seattle metro / Puget sound area streets & JYs too by now.
