ok so my Jeep has had a 160* stat in for years, but with the weather ive had some moisture issues in the valve cover and oil, presumably due to never getting hot enough to keep moisture from forming.

so i got a 180* stat, ran even colder. driving it would never get above 130, so then i go and get a 195, figuring maybe the 180 was defective.

throw the 195 in, still runs at 160. all temps are verified with a calibrated thermometer i use at work. i just cant figure this out, why would a 195 stat be flowing coolant at 160 degrees? the only time i can get it to 190-200* is by unlugging the E-fan, blocking the grill, closing the hood, and leaving it in gear so there some load on the motor.

then, as soon as i remove the grill cover and put it in neutral with the heat on she shoots right back down to 150-160.

the clutch fan is fine, coolant mix is fine, its just a stock '95 cooling system.
no air in the system either.

are STANT thermostats just garbage?

 

MY winters in MO caused me the same grief and I did the same things you have. My only fix was the blocking the radiator that seemed to work a little. Nine times out of ten you're not going to reach temp while driving especially in the sub 30 weather, at least what I have seen. Even my 07 taurus has the same issue in the uber cold.
Just some things I thought about were;
taking off the clutch fan for the season
using a 56/58mm washer with a 3/4 or 1/2 inch hole to take the place of the thermostat.

 

I went through 4 Stants from Napa before biting the bullet and getting one from the dealer.

 

And did the dealer one finally work?

People keep telling me to use cardboard...point is I shouldn't have to, that's why there is a stat.

 

Yes, they did. On all 3 of my Jeeps.

Cardboard won't hurt by any means.

 

I know it won't hurt, I have to do it on dads CJ. But I shouldn't have to use cardboard, every other 4.0 I've ever seen runs right up to 180 easily no matter how cold it is.

 

I've had a NAPA 180 and 195 in my XJ and had zero problems with either...maybe you got unlucky??

I would suggest trying a dealer stat before the cardboard trick, since that's just masking the issue...

 

I ran a 160deg in my 00 over the summer. It was still In there for a few weeks into the winter and man that thing would never heat up. I run a v8 zj clutch too. Now with the 195 it's back around normal with some cardboard in front of the rad probably due to the zj clutch. You can test your Tstat in some boiling water... But that's kinda an opposite test since your saying it's staying cold. Not getting hot...

 

Maybe I'll do the water trick tonight, but monitor the temp with my good thermometer and make sure they really are opening too early.

 

A 195 stat runs the same as a 160 and a 180 stat runs even cooler and all temps r verified with a calibrated thermometer????....hummm......really???? Does your heater work? If so, your gauge display is wacked. I've never had an issue with Stant stats and have installed dozens of them over 45 years of driving. I do test a new stat in a pot of water on the stove using a accurate cooking thermometer before even draining coolant.

 

Heat kinda works, but yes, I am checking temps with a GOOD electronic thermometer, which i know is accurate to a tenth of a degree. And the gauge on the dash is pretty damn close.

 

Just seems like if heat kinda worked and coolant temp was actually at 130, then heat would really suck, hardly work at all. The odds of that many stats malfunctioning that badly (30+ degrees below their rating).......I'm smelling tuna fish. More details needed.

 

Put a factory stat in it!!

 

.....and send me the bad ones so I can test them.

 

YEAH!