Another cooling question

F

firerod

Senior Member
I have a strange question. Does anyone know how much of a difference air temperature makes on engine temperature? My car was running hot on a 80 degree day (and a bunch of other days). I rechecked the timing, added two bottles of Redline water wetter, and changed the thermostats to 160's. Today I took the same route as before and my car ran much cooler, last time it maxed out at over 200, today 180. The air temp was in the low 60's. Just wondering if I fixed the problem or if it was the air temperature.
 
Air temp. Thermostats have little to do with the maximum operating temperature. They help bring the engine up to operating temperature quicker and maintain a minimum temperature. If it was me, I would be running 180 deg thermostats. Either way you will still have to address any overheating issues. Not that it totally works this way, but you have a 20 deg deferential in outside temp and a 20 deg difference in engine operating temp.
 
JSeery said:
Air temp. Thermostats have little to do with the maximum operating temperature. .
Click to expand...

The little bit of difference they can make is how much the restrict water flow. Some open wider than others. The Stant thermostat for a Subaru fits the Flathead and opens quite a bit wider than the brands listed for Flatheads. I could only find them in 170 degree, which is fine.

If you are driving a 1939 to 1941, you have an air flow problem because the crank mounted fan is low, and does not turn as fast as a pulley driven fan, which mostly run at 1.2 to 1.3 times crank speed.
 
An old rule of thumb was that the engine ran about 100 degrees above outside air temperature
 
I was thinking it had more to do with the outside temperature than the couple of changes I made. Looks like I might be getting the radiator re cored.
 
The outside temp has a lot to do with engine temp as we
all know. I spent over 2 years doing all kinds of temp testing
mostly in temps above 85 degrees. When having temp problems
REMOVE thermostats, they only cause the engine to run hotter
and have nothing to do with cooling. After the problem is solved
then try the stats. Most stats restrict the coolant flow and will cause
a hotter engine in hot weather, this will not be noticed in cooler
weather. The air forced through the radiator from forward motion
is what does most of the cooling. The wind also effects the cooling.
One day on a straight road 3 miles long with the wind straight down
the road from the North I was heading north into the wind and the
engine temp was close 15 degrees cooler then is was heading South
with the wind pushing the car. Don't forget the engine is working
harder going into the wind yet it ran cooler. I repeated this into the
wind test several times to verify the findings. This was posted on
this forum at the time the tests were done. G.M.
 
At what ambient air temps do your cars overheat? This year, anything much over 80 deg. caused bad overheating and shutdown!. I'm frustrated because this almost precludes summer driving and I've done all I can think of to fix the problem.
 
fordmerc7 said:
At what ambient air temps do your cars overheat? This year, anything much over 80 deg. caused bad overheating and shutdown!. I'm frustrated because this almost precludes summer driving and I've done all I can think of to fix the problem.
Click to expand...

Follow the test procedures I outlined and find your problem and correct
it. If you have thermostats start by removing them. Fill the radiator up
into the filler neck and look for compression bubbles in the coolant. G.M.
 
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