Thermostat orientation

R

RandyMettler

Senior Member
Is this the correct orientation for a thermostat. I'm 98 percent sure it is, but than there is the 2 percent that worries me. The photo below shows the thermostat orientation.
 

Attachments

  • 100_7836.jpg
    100_7836.jpg
    52.1 KB · Views: 172
Yah, I had one flip one me on my first test run. Driving on a short test drive, while constantly watching the temperature gauge, it went from 180 to 145 in a matter of seconds. I knew something was wrong. I drained the radiator an the thermostat was rotated. I have since put a third hose clamp just above the heads water outlets. I don't know of any other way of retaining the thermostat.

When this happens, the cooling capacity transfers to the side of the motor that the thermostat rotated, path of least resistance. In my opinion all flatheads should have temperature sending unit installed on both sides of the motor.
 
Last edited:
There are several methods to retain them and a number of threads on the topics. Examples are fine wires that fit between the head and the hose, or use a metal sleeve inside the hose.
 
I use chrome pipes between the head and radiator. The tube inside the short hose connecting to the head keeps the thermostat in place.

I saw the temperature go to hot (the top mark on the gauge is about 200 degrees) first, and then drop to the thermostat temp. With the water flow blocked by the closed thermostat, the water at the sensor had to get to 200 before the water temperature up in the neck of the head gets hot enough to open the thermostat. I drilled two 5/32" holes hear the edge of each thermostat to let some flow past the bi-metal thermostat mechanism. Now the temp comes up to the thermostat temp without any overshoot.
 
I use a little JB Weld on the flange. Works like a champ and heat resistant and also keeps water from bypassing the thermostat.
 
I'm getting ready to change the upper radiator hoses on my 37 and was told the shape of the hose will hold the thermostat in place. I'm I being misinformed?
 
Only original hoses had the rubber bulge I.D. that would hold the thermostat in place The re- production hoses do not have that and will not retain the thermostat. You must use an alternate method such as extra clamp or wire. I prefer the wire or soldered shim tabs on the thermostat rather than the clamps because they are too obvious from stock.
 
Zeke5180 said:
I'm getting ready to change the upper radiator hoses on my 37 and was told the shape of the hose will hold the thermostat in place. I'm I being misinformed?
Click to expand...

You are being misinformed. The original thermostats were barrel shaped and located near the radiator inlets. Modern thermostats need to be retained by some method.
 
Years ago I had seen some old original '42-'48 style hoses that had a noticeable bulge inside the lower end to hold the thermostat. At one time Drake had a picture of the same thing in his catalog.
 
You must log in or register to reply here.
Back
Top