Hey guys.
I have a 97 4 door 4x4
Truck won't reach operating temp of 195
I changed thermostats and old one was good.
I also have poor gas mileage
I was thinking it may be the fan clutch but is there a way to test it to know for sure(the fan is always on)

 

How do you know it's not getting to op temp?

Only way to know for sure is put a scan tool on it.

 

My scantoil shows 170ish as max and thermostat never opens... Drove for an hr squeezed the upper hose and it was pressurized.
It is going into closed loop on the 02 sensors but it's always cold and heat barley blows hot.
Second thermostat if it was Ts being stuck closed it would overheat.

 

That sounds weird unless you live in Siberia. I've seen cars overheat at 5-10 below zero F. Even at 170 degrees you should be getting pretty good heat. Perhaps you have air trapped in the system and you're not really measuring the water temp. That's about the only thing I can think of if the t-stat is functioning properly.

 

That is what it sound like is air in the cooling system some where .

 

plugged heater core would cause your no heat . but should be coming up to temp

 

Unless he has a oversized Rad and its cold out
My Old 81 Ram was like that I had a slant 6 and put a rad for a 318 in it never got up to temp unless I blocked half the rad with cardboard even in the summer it ran cold had a flex fan
Still have that van I should scrap it

 

Try this: put a thermometer under your hood overnight. in morning, before sun hits the hood do the engine off scan and check all your temp sensors against the thermometer. You'll at least have IAT and ECT to work with.
It used to be possible to install a Tstat wrong. Dont know if it is, now And if it was backwards, the engine heat would overshoot at the least before it opened.
Last ditch is to put it in a pot on stove, with water and a thermometer and note when it starts to open.

I was trying to settle an argument about something else and strapped a digital therm probe on the hose right at the thermostat gooseneck. then wrapped a couple layers tape around it. Never got past 170.

 

It's a stock rad..
I'm gonna try burpin it shorly

 

I burped the system seems good but won't exceed 175isj in temp, and gauge fluctuates quite a bit... Sighhhh.... This is giving me a headache, fan clutch seems ok, I'm gonna test the sensor may be bad later.
Any other ideas appreciated.