Would u install any stat, even a new one, without testing it 1st?

Those bubbles are not 'air'. They are gaseous H2O...water vapor. One does not drop it in boiling water, one should heat it up until it opens and check the temp at which it does...which may not happen until it is boiling with a 195' OEM rated stat. Boiling water will not hurt the thermostat at all... You must have read some myth that suggested otherwise.

I have read dozens of complaints of thermostats being stuck open at the first time they got hot enough to open. This seems to be a problem with the 'fail-safe' type of thermostats that just stay open when they fail. The OP said they bought a MOPAR thermostat, but they might have instead got one of these 'fail-safe' lousy stats...

Such a situation would result in the difficulties they have described...but may not be the only explanation.

Probably. There is an element of trust that should exist between the dealer and the customer. The OP said they bought MOPAR.

Are we to assume that MOPAR doesn't have their s*&t together? If we can't trust the supposed leaders in Jeep part industry, we need to completely rethink everything we have come to understand as customers.

I believe we should all rethink what we have come to believe as customers because this country has imploded because of the cumulative stupidity of the public and their belief that a brand name is all that matters. Quality means nothing when they see a brand name on a NASCAR or Indy car...

Keep in mind that absolutely Nothing that comes in a package that is labelled "Mopar" was manufactured by Jeep, or Dodge, or Chrysler.............

Every single part is manufactured by an aftermarket company, and is purchased by the Chrysler group to be re-sold under the brand label "Mopar"

R u saying a 195 stat may not open 'til water reaches 212?.....if u r, better toss that stat in the trash. A 195 should be visibly open by 197-198.

Where's the "jiggle valve" in that stat? Can't see it in the photo.

Yep! We, as customers, must start rethinking the way we shop.

One of the reasons I got this Jeep was because of all the Jeeps in the junkyard. The money I spend on JY parts goes to a neighbor, which hopefully will spend that $ I gave them locally too. Buying used stuff from a neighbor keeps much more of our work-energy local than if we bought new crap from China or Mexico.

We are all fuggin ****-poor now, and good paying work is hard to find...because we wanted to buy cheap **** made by slaves elsewhere. Now we are the slaves too.

Sorry to get political, but we need to wake the F up! I know that a lot of the folks here will understand this too, as Jeep owners are often aware of this kind of stuff.

Cheers to you for being a step or two ahead of the pack of consumeristic zombies that are overwhelming the US to it's demise.

That photo came from Google. I could have opened my engine to take the same picture but my thermostat seems to be working just fine and I don't want to mess up a good thing. I don't even know what brand of stat is in mine, but it works so I aint gonna mux it up.. I think it is a 195' er though...

195' starts to open at 195, but may not be fully open until 15' higher (according to what you typed in a previous post). That is 210'. If you factor in a degree of acceptable error in manufacturing of 2 or 3 degrees, then that could easily mean the stat could be fully opening at 212 or more...

With a 195' stat that is fully open at 210, it is perfectly understandable that 210' running 4.0 are not simple mythology...

Remember the FSM is written by crafty engineers and lawyers. They don't print any numbers that can be construed as an absolute.

That way no one can claim their Jeep doesn't run or act "by the numbers" and try to get free work and parts.

And speaking of absolute, dash gauges in cars have not been known to be very accurate, and likely don't really need to be if they are fairly close in calibration.

I've overheated vehicles where the thermo wasn't replaced after repair, and never had issues, and it would have been exposed to air/steam/vapor/ boiling water/whatever.

Doubting Thomas here would need proof that boiling water harms it, such as an SAE paper/report, not just interwebz BS, as I think it would act the same no matter what medium it was regulating, could be water, air, whatever.

Gee, did OP ever get it sorted out?

He's busy boiling water and testing thermostats.

Why not cook the thermostat in the fluid that it operates in, like antifreez. Then you should be able to hit the 212 degrees without the bubbles.

Fire hazard. Poisonous fumes hazard. Antifreeze will burn.

Bubbles make no difference in temperature checking, for our purposes.