TJ Radiator

The thermostat controls how cold the engine runs. It will stay closed until it's rated temp is reached, then it allows flow.

So no matter what radiator or even if you plumbed it right into a lake like a boat does, the engine will run at 195 F with a 195 t-stat in it.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's

Brian Hawke wrote:

Mike, I thought that the thermostat would open at 195 degrees, didn't think that it determined engine running temperature. Frank Sawin

It only controls how 'cold' the engine runs and how 'hot' the heater blows.

It basically stays shut until the engine reaches the t-stat's temperature. In modern engines, this is usually 195 F to make all the emission and mixture controls start working.

In old carb engines, folks used to use a 180 for the summer and switch to a 195 in the winter for internal heat.

If you have a 180 in the winter, then on a cold day the engine will only be forced to run at 180 F. This makes for lousy heat inside the cab. Put in a 195 and it forces the engine to heat up to 195 before opening giving a lot more heat from the heater.

If the engine has issues and wants to run hot, then a t-stat has no effect unless the old one was broken. Putting a 'colder' one in won't change a thing for top end heat.

I have gone through 4 t-stats recently hoping they were bad.... My CJ runs right at the freaking edge for overheating because I have a warn

9000i winch and Hella black Magic lights blocking the air flow.

On a hot day, or if I run extended at 75+ mph I will boil over unless I turn on the heater blower to draw that little extra heat out of the system. Then the gauge drops like crazy.

I need more capacity (rad was new and recently flushed) or to rearrange the front of my Jeep so I am thinking on a 3 core or at least a V8 rad to replace the one I snapped in half a couple weeks ago. I might try a shroud first, but that costs almost the same as a rad and I do need a rad. My soldering job might hold, but....

So I guess we see the results of playing with t-stats a lot easier up here in The Great White North due to the immediate effect on the heater. LOL!

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's

Why do you bother?

The thermostat only controls how cold the engine runs and how much heat you get inside and how long it takes to warm up to operating temperature. Simple eh?

(we don't really care about hybrid technology and electric pumps on our current Jeeps eh.)

Put a 180 t-stat in and at -30 you will never get any hotter than 180 F so you will freeze you butt off inside the Jeep. NO matter how big a heater core you put in!

Put a 195 in at -30 and you will have at 'least' 195 deg water. You will not get up to 210 at -30 but have a decent chance of hitting the

195 because there is no coolant flow.

Put a 180 in at -30 and the temp sensors will always say cold so the emissions will not 'turn on' to 'run' mode they will stay in 'warm up' or 'choke' mode because it will Not get any hotter than 180. (use what ever fancy term you want, open loop, closed loop, etc.)

Heaters have had thermostat bypass hoses since they made thermostats. That only means you get luke warm coolant while the engine heats up to the temperature dictated by the thermostat.

In the real cold, if you use the heater blower while the engine is warming up, it will take twice as long to warm up the engine due to that bypass hose. Let it sit with the heater fan off (or on real low because you now have no choice as the fan stays on) so no heat is sucked away from the engine's coolant until the temperature gauge starts moving and you will have 'good' heat 'way' faster.

AMC did Not put radiator fan shrouds on a whole bunch of Jeep CJ7's. There was/is no place to even bolt one to on mine. (some CJ's did come with shrouds, depends on the area market and engine)

Mike

mic canic wrote:

Mike is right on. Go with the proper 195 degree thermostat, nothing will work right if you don't.

Jerry