After installing a new radiator last summer, I was well pleased with the cooler temperatures my T ran.
But now its winter and a ride in 35 deg weather often shows no red in the motometer at all.
So .... given that a T has no thermostat, can it run at to low a temp ? In a modern car no thermostat is a bad thing. Running too cool means poor efficiency and perhaps poor circulation of the oil.
Does anyone use a little cardboard over the radiator to get temps up to normal?
Yes, in the day, blocking off the cold air through the radiator was the thing to do and I believe that is still a good practice. There were many variations of covers.
You can find quite a few vintage options at:
If you want to try a cheap invisible solution, Lang's sells 160 degree accessory thermostats for T's without water pumps: http://www.modeltford.com/item/A-TH60.aspx
Or a piece of cardboard that is cheap and easy to size.
You can see the same technology being used on diesel trucks this time of year. Sometimes the best answer is the easiest, cheapest one.
One could make the case that the T's operating temperature is self regulating. Without a water pump, the coolant will not flow until the coolant in the block is warm enough to make it less dense than the water in the radiator. Water has to get pretty warm for its density to change.
Hal, that number would be 100 degrees above ambient (outside) temp for optimal efficiency. I checked my temp with a probe this summer and found my car to run about 70-80 degrees above ambient in normal driving. Even idling, I rarely got above 90 degrees ambient.
I may be over-thinking this, but if the radiator is blocked off it will keep the engine bay warmer, which would keep the oil warmer and thus more likely to flow through the engine with less resistance. A cold radiator would allow cold air around the engine, and the coolant inside the radiator and the engine would be at a lower temperature. Seems like some sort of heat retention would be welcome, and wiring a piece of cardboard to the radiator seems simpler than installing a thermostat.
Thermostat is year round, automatic. I use a 180 and waterpump.
Water doesn't magically get to some temperature, then change density. This chart gives you the idea: any temperature differetial will cause thermosiphon. The combustion chamber has an ideal temperature. Too much cooling, and you have to run rich, causing even more cooling.
If your radiator is good, you could also take off your fan belt if you are worried about over cooling.
Obviously the pure water used by many could freeze while sitting, but I wonder if the radiator small passages ever froze up while driving (wind chill factor? Is that possible?) back in the day while using just water in places that get very cold winter temps. Was that part of the issue with putting blankets over the radiator face while operating in severely cold conditions?
With diluted antifreeze or just water, can freeze while driving I have had it happen and have seen many steamers in the winter.
An early model of Volvo had a window blind that pulled from the inside to raise and lower for temperature control.
I stand corrected, Ralph. I was remembering a rather shallow gradient that steepened near the boiling point. That changes more than I thought.
Once I had my Dad's '51 Ford V8 freeze after about 6 miles of driving in -30F temp.
All that time the coolant was flowing in the engine and heater.
I stopped covered the radiator in front with newspaper and clothing, waited a few minutes until engine heat thawed the radiator out.
I then drove slowly to the next town, checked the coolant and found it was good for -20F.
In those cases freezing will not cause the block or radiator to bust open, the coolant will just slush-up and quit flowing.
Some think water has to start boiling before you get thermosiphon. Not true. On a cold day you can drive all day with the coolant temp below any figure you want if the weather is cold enough.
If you hold a lit match at the water inlet on the side of the block you will get therosipen.
The warmer water will not flow toward the radiator as that would be going down. water being heated must rise.
Ford called the model A cooling system pump assisted thermosiphen.