Thermostat not opening? Help!

[WadiaAbushanab]

Hello everyone. A while back I wired up a switch directly to the fan so I could turn it on when I drove because I had an overheating issue. I just cut the sensor off the bottom of the radiator and wired up a switch to the fan. Everything worked fine, coolant circulate, thermostat worker. I got a new thermostat and radiator, and now it seems it’s not circulating and the thermostat must not be opening as it climbs up to 190 within minutes. Did I need this sensor for the radiator to open? Why all of a sudden with the new thermostat it just doesn’t seem to work?

[WadiaAbushanab]

Hello everyone. A while back I wired up a switch directly to the fan so I could turn it on when I drove because I had an overheating issue. I just cut the sensor off the bottom of the radiator and wired up a switch to the fan. Everything worked fine, coolant circulate, thermostat worker. I got a new thermostat and radiator, and now it seems it’s not circulating and the thermostat must not be opening as it climbs up to 190 within minutes. Did I need this sensor for the radiator to open? Why all of a sudden with the new thermostat it just doesn’t seem to work?

Forgot to mention I also drilled a small hole inside the thermostat as suggested to help remove some of the air. I tried to bleed the system best I could I don’t know how else to make it circulate coolant.

[Nut124]

The switch has nothing to do with the thermostat opening.

Rather than cutting the fan switch off, you could have added the manual switch in parallel with the existing thermo switch. That way, both could start the fan.

You either have tons of air in the system, a bad thermostat or it is installed wrong.

[blazingspider]

The easiest way to check the thermostat (if you think it's bad) is to place it in a pot of water with a thermometer, put it on the stove and heat it until the water starts to boil. You'll be able to see the valves open when it approaches 180 degrees or so.

[ORFORD2004]

Put a T on the heather hose in back of the head. That's the higiest point to fill. Turn ON heather valve. Prestone sell one to flush the system.
Also, are you shure that you did not leave plastic plug in the radiator?

[WadiaAbushanab]

Put a T on the heather hose in back of the head. That's the higiest point to fill. Turn ON heather valve. Prestone sell one to flush the system.
Also, are you shure that you did not leave plastic plug in the radiator?

What plastic plug in the radiator? I only know about the plastic drain plug on the radiator

[TX82FIAT]

At the high point of the cooling system . There is a coolant hose near the passenger side fire wall. At the highest point of that hose you cut the hose and insert a T fill plug. High point to fill and let air escape as you fill the cooling system. Some good advice above. A switch wired in parallel with the bottom of the radiator temp switch is a better option that unhooking the sensor to turn on the fan manually. The parallel switch give you the ability to turn the fan on manually in advance of sitting in bumper to bumper traffic or having the fan come on automatically when temp rises. The temp T on the passenger side near the water pump that you drilled a hole in is most likely not opening for some reason. I suspect you still have air in the system preventing the coolant from flowing and opening up the new switch. As mentioned, you can test the T stat in a pot of boiling water. But, my guess is that you have air in the system someplace trapped. As you fill the coolant try squeezing the soft large hoses to force the air to move in the system and fill as you go. This process of squeezing the air out towards a high point in the system is called burping the system. These cars can be fickle to cool if air is in system. If you still don't have have coolant flowing try running the car for ten minutes, burping, running the car for 10 minutes and burping. Monitor your coolant overflow tank to make sure it is not dry and sucking air back into the system when engine cools between cycles. You got this, it just takes toim patience and time unless there are issues someplace else in the system.

[Nut124]

Just do not burn yourself. Do not open the radiator cap while hot, pressurized.

[WadiaAbushanab]

At the high point of the cooling system . There is a coolant hose near the passenger side fire wall. At the highest point of that hose you cut the hose and insert a T fill plug. High point to fill and let air escape as you fill the cooling system. Some good advice above. A switch wired in parallel with the bottom of the radiator temp switch is a better option that unhooking the sensor to turn on the fan manually. The parallel switch give you the ability to turn the fan on manually in advance of sitting in bumper to bumper traffic or having the fan come on automatically when temp rises. The temp T on the passenger side near the water pump that you drilled a hole in is most likely not opening for some reason. I suspect you still have air in the system preventing the coolant from flowing and opening up the new switch. As mentioned, you can test the T stat in a pot of boiling water. But, my guess is that you have air in the system someplace trapped. As you fill the coolant try squeezing the soft large hoses to force the air to move in the system and fill as you go. This process of squeezing the air out towards a high point in the system is called burping the system. These cars can be fickle to cool if air is in system. If you still don't have have coolant flowing try running the car for ten minutes, burping, running the car for 10 minutes and burping. Monitor your coolant overflow tank to make sure it is not dry and sucking air back into the system when engine cools between cycles. You got this, it just takes toim patience and time unless there are issues someplace else in the system.

Ok thank you and everyone else. I’ll try all of these

[WadiaAbushanab]

Is there a way I can force the thermostat open so it just stays open all the time and doesn’t close?

[Nut124]

Not really. And you do not want that. I have never had a problem in 30 years. They work 100% when installed correctly. Yours would be the 1st one not working that I have heard.

Did you test in in a pot of boiling water?

The port that is always open goes to the pump inlet. The port that is blocked goes to rad btm. When cold, coolant flows from the T at the head to the pump inlet.

Get it installed correct, jack up the front and get the air out. Fix the rad temp switch to control the fan in addition to your manual switch.

[TX82FIAT]

I would not force the T stat to stay open because the shorter cooling loop prior to temp helps bring the car up to temp faster and then open the longer more effective cooling loop. I have seen some people remove the smaller cooling loop on race cars but I would not advise it for an every day driver. Don't know where you live, but if it gets cold there you will want the cooling system as designed.

[WadiaAbushanab]

I would not force the T stat to stay open because the shorter cooling loop prior to temp helps bring the car up to temp faster and then open the longer more effective cooling loop. I have seen some people remove the smaller cooling loop on race cars but I would not advise it for an every day driver. Don't know where you live, but if it gets cold there you will want the cooling system as designed.

I tested my new thermostat by putting it in boiling water and it never opened. So it was defective I guess. I just had to jam it open for now