Favorite Thermostat ?

Good morning all ! Looking for a general consensus here .I have been running a Stant Superstat # 45358 in my 56 CJ5 F -head . It seems to have to get unusually hot on my temp gauge before opening ; 250 degrees or more . First , is this unusual , second , could it be that temp sender is at back of engine , and thermostat is at front . It's really unnerving watching the gauge climb that high . Cooling system has been cleaned out , and radiator is new . Thanks

 

Have you ascertained that your gauge and sender are accurate? At 250ºF I'd expect to see the radiatior boil dry.

Secondly, did you refill the coolant system just recently? They often need to be "burped" after a coolant change. You may be seeing the effect of a 'bubble' trapped in the block, overheating in the area of the sensor.

Another cause of vapor bubbles can be head gasket leaks.

Does your thermostat have a small bleed hole through the flange? - this allows bubbles to pass, and also channels hot water to assist it in sensing and functioning more responsively.

 

Test the thermostat in a pan of water with a thermometer.

 

Bien sur.

 

This is occurring before thermostat opens , so radiator is still cold . thermostat does not have bleed hole in it . Did just refill with coolant .
Assuming gauge is reasonably correct , temp does go to a steady 180 after thermostat opens . How do I burp system to eliminate air ? Thanks

 

You said your sender is at the back of the engine. Is this a V6 or 4 banger? If this is a v6 I'm gonna guess your jeep is a late 70 or 71 production.

 

Does anyone know what brand of thermostat already has bleed hole in it already ? I've checked 6 different brands
for this application , and none have it already .

 

It takes about 7 seconds to drill a 1/8 hole toward the top of the new thermostat. I usually try to buy Stants.

 

I loosened the temperature sender in the manifold till I got coolant out of it, don't know if this will solve the problem.

 

Thanks guys . I'll replace it and drill it .

 

X2

 

Depends. It may take a few warm-up cycles and some topping off. Sometimes it may mean pulling one hose off the heater and backfilling it, or something similar.

 

Replaced thermostat today . Drilled 1/8 " hole in flange , burped system by cracking open temp sender til coolant came out . Started up ,warmed up , temp rose to about 190° then settled down to about 180° ( 180° thermostat ) . All your sage advice worked perfect ! Thanks guys !

 

Thanks for the feedback - that way we all keep learning.

 

I work as a partsman at a garage full of mechanics . But this site is where I go to find out what makes my old Jeep tick . One thing I have learned , is that there is no substitute for experience . I occasionally may be able to offer advice , but do benefit from the wealth of information here . Again , thanks .

 

This is what I do too. I'm running an odd fire with a 180 thermostat.