Not another cooling system thread

Jamison C

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Oh yes, another cooling system thread.

I bought my Jeep in May and did a cooling system flush a couple weeks after. I always felt it ran low in terms of temperature (like 190-195) so I replaced my thermostat and radiator cap when I did the flush. PO had a 13lbs cap on the system, with a 195 thermostat.

Deciding to do the flush on a whim, I went to O’Reily’s and bought their store brand cap and thermostat (I know I know). Got it all together, Jeep ran about the same at 190-195 via OBD. I shrugged it off thinking it had to do with the year. My previous 2002 always sat right at 210 on the gauge but I don’t think I ever checked it with the scanner.

Anyhoo I went to Flagstaff on Monday to go play in the fresh snow and I was pretty bummed that the heater was not singeing my eyebrows off like my last TJ did, even with the hardtop and full doors. It was lukewarm at best. I decided to throw the scanner on and found the engine was running at a whopping 180-190°. That may not seem like much but that extra 20-30° makes a large difference. This could also contribute to why my Jeep on humble 31s is getting 12-13 mpg whereas my last TJ on 32s was consistently getting 16.
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I’m one of those guys that saves old parts and I’m glad I did. Last night I dug out my old thermostat and noticed it was a USA-stamped Stant 195, though I’m not sure it’s a superstat. Either way I threw it in a pot of water and brought the temp up and down several times to make sure it was functioning, and it passed the test. Satisfied, I threw it in the Jeep along with a new Felpro gasket. The results were satisfactory, with my highest engine temp (ambient air around 40°) reading in at 206.6°, and the heater making me sweat like my last TJ did. I’m hoping this will help with my gas mileage.
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Just for fun, I threw the faulty thermostat in water, and that sucker was wide open at 185. Even after turning the stove off and letting it cool, it was still slightly open at 170. You can see the gap is wide open below. There’s a part I won’t be saving:)
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Drove it around a bit today with the scanner on and it was averaging between 199-204. I feel like it should still be a little higher, but I’m probably just being anal. I also bought a new Stant radiator cap just for peace of mind.

Point being, plan ahead and don’t skimp on parts just because you’re in a rush. If y’all wanna take some OBD numbers on your average temps I’d love to hear some feedback.
 
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My O.G. cooling system at 110K (I know, I have all the parts waiting for me in the garage) runs at around 210 or a tad higher. I get decent MPG (19 highway when I'm easy on the skinny pedal) and heat. I recently searched the FSM but couldn't find what it should be at in there. I know some here have said 210, but I have no idea where that comes from.

In a recent thread, I talked about how I have tested new stats prior to install. I have a Stant on the shelf that I will still be testing!
 
Some things you can get away with and others no no no.

Cooling. Nope. Although OEM radiators can be shit too.
U joints...
Tires....
Wheel bearings..
Steering components...
All really need top quality replacement parts.
So far I’ve had good results with the $100 CSF radiator the PO put in. It did great over the summer so I just have to see how it does in terms of longevity.

Thanks! I’ll see if I can milk the extra few degrees out of it with a new cap on the chance my current one isn’t holding pressure properly, or even too much. Stant tests each cap so I know I’ll be getting a true 18lbs out of it.
 
I guess this is just further evidence that you should always spend more on reputable parts from quality manufacturers. Thanks for posting this though, it’s actually very informative.

The first thing that always comes to mind when people talking about their heat not getting hot enough is the thermostat.
 
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So just got back from Flagstaff where it was a mild 30°. Engine temp fluctuated a lot between 197 and 204 which isn’t horrible. In fact the heater was nice and warm. But I’m beginning to think that the thermostat is opening too wide too fast which is causing the temp to be so inconsistent. I can watch the gauge and tell exactly when it opens. My last TJ did not do that.

I’ll be ordering either a Mopar or Stant Superstat tomorrow to see if they’ll be a little more consistent in moderating the temperature. Maybe I’m being way too picky, but I don’t think the temps should be bouncing around every 30 seconds or so.