Ford/very little heat output
uncle duke wrote at 2015-01-28 14:26:46
Disconnect both heater core hoses and apply compressed air to one port of the heater core and a small catch bucket under the other to catch the rust/crud that comes flying out so that you don't make a mess in the engine compartment. When you're sure that's good enough disconnect the same hoses going to the intake. Check for rust blockage. The way I check the fan clutch is when I shut the engine off I quickly look under the hood to see if the fan stops "on a dime". A couple seconds of spinning after the engine is off is o.k. but if the fan keeps spinning, anything really more than 4-5 seconds tops should be look at. That would be more of a problem for summertime cooling, though. About the thermostat- if it didn't come with a pilot hole drilled in the flange area you should drill one 1/16th or so to bleed the system of air. It'll save on collapsed hoses on down the line.
uncle duke wrote at 2015-01-28 14:55:08
....If you would like to try the cardboard idea Brian suggested make the cardboard piece taller than half the height but just under 3/4 height of the radiator. You will want the orange temperature needle to be close to the middle of the "O" in normal, maybe the right side of the "N" in normal. When you start getting towards the "R", I'd say you're pushing it. Just trim an inch at a time until good. Even though it's in the normal zone it's more than likely in the 220-230 zone temp. wise. Be careful. Also, keep in mind some sensors/units may read differently than others. It's pretty comfortable in the cab, even when it's 40 below, using the cardboard in front of the radiator. It'll work but paint it black to make it look less obvious and when temperatures warm back up don't forget to remove it. Just put it behind the seat for future use. Do this only after you check everything I posted just previous above. If you want an easier starting engine in wintertime use 10w30. It'll spin easier when starting vs 10w40. My truck is a few years older than yours but I'm approaching 600,000 miles on the original v8 engine and trans, really.