Which thermostat is best?
Senior Member
Joined: Nov 2014
Posts: 766
Likes: 5
From: Los Angeles, CA
Year: 1989 Limited
Model: Cherokee(XJ)
Engine: I-6 4.0L AMC Renix
The colder the engine, the more wear it has, that's why you are never supposed to drive hard before the engine has fully warmed up. I constantly tell my dad to put in a higher thermostat because he has a 160 in his ZJ and it runs cool all the time. I can't imagine the wear that's happening in the engine because he is an aggressive driver. The engine runs at 210 for a reason. It's where it gets the best performance and less wear. I live in Los Angeles and it normally gets 100-110 in the summer but I would still stick with 190-195. 180 is the lowest but It's pushing it.
So why do you think there are so many inquiries in the category "Why is my Jeep always running hot"? Let me give you some combustion facts: 1) 1 gallon of gasoline 1" deep produces 187,000 BTU's in under 30 seconds; 2) the average gasoline explosion in a cylinder exceeds 2000 deg.F; 3) cooling systems are designed to keep the engine from melting, not "efficiency"; 4) water with coolant boils at slightly over 218 Deg.F and will over pressure the radiator and can cause the head gasket to leak. So when people like you say, well jeeps like to run hot, or it's more efficient at hotter temperatures, etc. etc. you are leading people down a path that is neither correct or will prolong the life of the engine. Changing the oil and keeping coolant in the motor and preventing melt down will prolong it's life! Not running hot and over heating the first time you have to stop at a light with the AC on. So get a clue, it doesn't prolong the engine life to run it HOT!
Banned
Joined: Feb 2014
Posts: 2,379
Likes: 18
From: Florida
Year: 2000
Model: Cherokee(XJ)
Engine: Golen 4.6L
Not only that, radiators are made to handle pressures exceeding anything the cooling system will experience, but just in case, there's a pressure cap on it that releases excess pressure. Jeep even installed an overflow bottle so it wouldn't just pour out onto the ground.
Further, the pressure inside the cylinder from the compression and ignition of the fuel/air mixture exceeds any pressure you could put on the cooling system, and the head gasket is made to withstand that. Again, the radiator cap would let the pressure out before it got anywhere near that level of pressure.
So stay in school! Otherwise you won't learn all this, and you'll continue making hilariously ignorant posts that cause people to laugh at you.
::CF Moderator::
Joined: Aug 2011
Posts: 43,971
Likes: 1,578
From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
When you get into 11th grade chemistry next year, you'll learn that pressure raises the boiling point of a liquid. Water in a cooling system pressurized to 12 psi boils at 258°. Add coolant to it in a 50% mix, and you raise the boiling point up to around 266°.
Not only that, radiators are made to handle pressures exceeding anything the cooling system will experience, but just in case, there's a pressure cap on it that releases excess pressure. Jeep even installed an overflow bottle so it wouldn't just pour out onto the ground.
Further, the pressure inside the cylinder from the compression and ignition of the fuel/air mixture exceeds any pressure you could put on the cooling system, and the head gasket is made to withstand that. Again, the radiator cap would let the pressure out before it got anywhere near that level of pressure.
So stay in school! Otherwise you won't learn all this, and you'll continue making hilariously ignorant posts that cause people to laugh at you.
Not only that, radiators are made to handle pressures exceeding anything the cooling system will experience, but just in case, there's a pressure cap on it that releases excess pressure. Jeep even installed an overflow bottle so it wouldn't just pour out onto the ground.
Further, the pressure inside the cylinder from the compression and ignition of the fuel/air mixture exceeds any pressure you could put on the cooling system, and the head gasket is made to withstand that. Again, the radiator cap would let the pressure out before it got anywhere near that level of pressure.
So stay in school! Otherwise you won't learn all this, and you'll continue making hilariously ignorant posts that cause people to laugh at you.
CF Veteran
Joined: Nov 2010
Posts: 15,581
Likes: 8
From: some small town oregon
Year: 1989
Model: Cherokee
Engine: 4.0
I'm just going to say this. People complain about overheating because of **** poor maintained cooling systems. Not because of a thermostat. All over heating problems can be traced back to these items. None include a working 190° thermostat.
Stuck thermostat, clogged radiator, bad clutch fan, bad electric fan, no fan shroud, fins on water pump rotted away, obstructed radiator, bad head gasket, cracked head, and last debris filled radiator or condenser.
You walked into a gun battle with long time mechanics.... All while you're holding a stapler. Give up while you're slightly behind.
Stuck thermostat, clogged radiator, bad clutch fan, bad electric fan, no fan shroud, fins on water pump rotted away, obstructed radiator, bad head gasket, cracked head, and last debris filled radiator or condenser.
You walked into a gun battle with long time mechanics.... All while you're holding a stapler. Give up while you're slightly behind.
CF Veteran
Joined: Sep 2013
Posts: 1,552
Likes: 7
From: California
Year: 91
Model: Cherokee
Engine: 4.0
::CF Moderator::
Joined: Aug 2011
Posts: 43,971
Likes: 1,578
From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
I'm just going to say this. People complain about overheating because of **** poor maintained cooling systems. Not because of a thermostat. All over heating problems can be traced back to these items. None include a working 190° thermostat.
Stuck thermostat, clogged radiator, bad clutch fan, bad electric fan, no fan shroud, fins on water pump rotted away, obstructed radiator, bad head gasket, cracked head, and last debris filled radiator or condenser.
You walked into a gun battle with long time mechanics.... All while you're holding a stapler. Give up while you're slightly behind.
Stuck thermostat, clogged radiator, bad clutch fan, bad electric fan, no fan shroud, fins on water pump rotted away, obstructed radiator, bad head gasket, cracked head, and last debris filled radiator or condenser.
You walked into a gun battle with long time mechanics.... All while you're holding a stapler. Give up while you're slightly behind.
::CF Administrator::





Joined: Feb 2011
Posts: 14,479
Likes: 805
From: Blunt, South Dakota
Year: 97
Model: Cherokee (XJ)
Engine: 4.6 stroker
I say go with 160 degree thermostat!
I have owned 5 jeep Cherokees and every one of them ran hot and did not do well in stop and go traffic with the AC on. I just replaced my a blown/cracked radiator, I believe due to over pressure due to a 195 degree thermostat. I decided to install a 160 degree high flow thermostat and guess what? It now runs consistently under 210 degrees (180-190) in stop and go traffic with the AC on. I also pull a small trailer with my 1993 Harley over the Sierra's and it still stays under 210 degrees.
I have owned 5 jeep Cherokees and every one of them ran hot and did not do well in stop and go traffic with the AC on. I just replaced my a blown/cracked radiator, I believe due to over pressure due to a 195 degree thermostat. I decided to install a 160 degree high flow thermostat and guess what? It now runs consistently under 210 degrees (180-190) in stop and go traffic with the AC on. I also pull a small trailer with my 1993 Harley over the Sierra's and it still stays under 210 degrees.
So why do you think there are so many inquiries in the category "Why is my Jeep always running hot"? Let me give you some combustion facts: 1) 1 gallon of gasoline 1" deep produces 187,000 BTU's in under 30 seconds; 2) the average gasoline explosion in a cylinder exceeds 2000 deg.F; 3) cooling systems are designed to keep the engine from melting, not "efficiency"; 4) water with coolant boils at slightly over 218 Deg.F and will over pressure the radiator and can cause the head gasket to leak. So when people like you say, well jeeps like to run hot, or it's more efficient at hotter temperatures, etc. etc. you are leading people down a path that is neither correct or will prolong the life of the engine. Changing the oil and keeping coolant in the motor and preventing melt down will prolong it's life! Not running hot and over heating the first time you have to stop at a light with the AC on. So get a clue, it doesn't prolong the engine life to run it HOT!
You have two ears and one mouth, they are best used in proportion.
::CF Moderator::
Joined: Aug 2011
Posts: 43,971
Likes: 1,578
From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0




