40 ford flathead operating temperature

V

vetpenny

Senior Member
After running my pickup for about 1 hour in normal traffic, my temperature gauge is about 3/4 (midway between N and H). When I stop it climbs up to H but once I am moving it returns to 3/4. I do notice on occasion after driving for about an hour sometimes the starter barely turns over but it does start. Also the radiator has never boiled over. Do you think I have a problem and if so I would welcome suggestions. Thanks for your help.
 
You need to check the temperature with an infared temperature gun and get an accurate reading. The guns are relatively cheap online.
 
Doesn't sound like it, but as suggested, determine what temperature it is actually running at.
 
vetpenny said:
I do notice on occasion after driving for about an hour sometimes the starter barely turns over but it does start.
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Assuming the truck has not been converted to 12v, make sure you have the correct (i.e., larger) 6v battery/starter cables and that all connections are clean. Also, make sure the engine is grounded to the body.
 
I just did some testing on a '40 pickup yesterday. I used a meat thermometer in the radiator. 3/4 on the temp gauge was 180 degrees. Just a little over half way was 160 degrees. It never did get to "H" on the gauge, but I suspect that H is 190 or 195.
 
TJ said:
I just did some testing on a '40 pickup yesterday. I used a meat thermometer in the radiator. 3/4 on the temp gauge was 180 degrees. Just a little over half way was 160 degrees. It never did get to "H" on the gauge, but I suspect that H is 190 or 195.
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I agree with your analysis.
 
My 40 Sedan runs around 185 at the lowest temp. As long as it is not boiling over and the radiator cap has not blown off,I figure that I am good. Also I use an insulator under the Carb (coolcraft) and the carburetor is at least 100 degrees cooler than the manifold. It seem to work well.
 
I have some bellows thermostats from Ford (script box) and they read 160 degrees on the box. I suspect that on my 40 wagon that would be the N line reading. We drove the wagon last Saturday on a 100 degree very humid day and it ran slightly over that mark and when idling at a stop light went higher but came back down when moving, H mark is about 190/200 using an infrared heat gun
 
I lives with overheating for a while on my stock V8 finally tried everything in the book


I would suggest you re-torque the head bolts if they have not been done in a while. I also put in a set of Skip Haney high flow water pumps. but vote start with the head - I did discover 6 of them that only took approx. 20 ft/lbs to crack loose all the others in the 60 ft/lb range
 
Hi Everyone. vetpenny, if it isn't boiling or spilling fluids, your cooling system is working.

The weak starter, I'll leave to others.

I just might check the torque on my head studs, only because I've never done it.
 
alanwoodieman said:
I have some bellows thermostats from Ford (script box) and they read 160 degrees on the box. I suspect that on my 40 wagon that would be the N line reading. We drove the wagon last Saturday on a 100 degree very humid day and it ran slightly over that mark and when idling at a stop light went higher but came back down when moving, H mark is about 190/200 using an infrared heat gun
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Sounds like your engine has NO heating problems. One thing
that helps is the old original bellows stats that have large flow
openings and don't restrict the coolant flow. G.M.
 
Yes, the water flows out of the head up the neck, radiator hose to the radiator. Check the neck part of the head below the radiator hose. That is about the same location as the stock temperature sensor.
 
JSeery said:
Yes, the water flows out of the head up the neck, radiator hose to the radiator. Check the neck part of the head below the radiator hose. That is about the same location as the stock temperature sensor.
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Thanks It will be interesting to see how that temp compares to other parts of the engine and radiator.
 
Your starter problem may be heat, setting close to the exhaust manifold they can get hot. I had a 51 ford that I had to put some insulating blanket around the started to keep it from getting so hot, had to sit and wait for it to cool off so it would turn the motor over fast enough to start. Had no more problem with starter after that. My heat gun show's temp. of radiator running at idle for 1 hr. now (doing a test) at 171 F. on gauge's 3/4 mark. Al
 
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