Water will conduct heat weather its moving fast or slow. If he overheated without a thermostat it's because he overheated with one before. That's why he took it out.

You want one in there for allot of reasons. Having the oil flow and the fuel atomize is a good start. If I got it strait Renix will run rich in open loop till warmed up, then the brain and the O2 ect will start controlling the mixture. Of course if it's cold enough you may never warm up without a t-stat.

 

you will be fine running without a thermostat around the city, offroad, or on the highway. unless it is really cold, then the engine might not get warm fast enough for your comfort.

alot of wrong information in this thread.

the coolant always flows at the same speed, if you remove the thermostat, the water pump doesn't automatically run at 1,000,000 rpm pumping fluid so damn fast it has no chance of doing it job....that crap doesn't even make sense.

do some research on what a thermostat does, and how it works....don't trust everything you read on these forums.

 

Plenty of us need to do some research. In any motor, the cylinder(s) closest to the water pump run cooler than the cylinder(s) farthest away from the pump. T-stat has nothing to do with which cylinders run cooler, which ones run hotter. That has to do with motor design/layout.

The FSM simply says "do not operate the motor without a t-stat". No mention of exceptions regarding driving conditions. My guess is the FSM is mainly referring to street motors

Again, the t-stat does one thing.....control MINIMUM coolant temp, nothing more.

Coolant flows at an infinite number of speeds/rates/volumes between min/max all determined by how open the t-stat is and the rpm at which the water pump spins.

Once coolant temp reaches the t-stat open temp, the t-stat opens very slowly and kinda "hovers" in an infinite number of open positions between closed and max open. T-stat max open is +/-15 degrees above its open temp.

Once the t-stat has reached max open, it's the same thing as not having a t-stat.

Ambient temp and cooling system component condition are probably the 2 main areas effecting max coolant temp, however, there are others as well.

 

I have a 94 cherokee and i have it now for like 5 years and since then i've been driving it without a t-stat and also its previous owner was driving it without a t-stat, and it did not over heat, infact when i drive on the highway on a 65-75 miles speed my temp becomes 155F in the summer when it is about 60 C in the afternoon here ..
and with the A/C on while i am not moving for a long time it remains 160F and when driving even lower than that .. eliminating the t-stat helps ur engine cooler .. i am saying this for a self experince not hearing this in other forums .. i live in kuwait and its hot like hell in the summer here .. all cherokees here in kuwait ppl eliminates the t-stat..
the only problem is in winter it warms up for too long .. last week i was driving on the high way on a 75 miles speed and the engine temp was 120F .. it did not overheat and the engine was running fine, i drove it for a whole hour and i always do that .. without a t-stat..

 

I think your gauge is fibbing a little.......60C ambient, a/c on, driving slow and gauge reads 160, even without a t-stat??????????????

 

100% correct!

 

Again, the cylinder(s) closest to the water pump (on any motor) run cooler than the cylinder(s) farthest away from the water pump.

 

Not going to get into the better or worse debate about running a thermostat, just want to correct a statement I see all the time in these threads. A wide open thermostat is not the same as not having one. A thermosat installed in the opening in the head reduces the size of the orifice. Smaller orifice equals less volume passes through which increases the residual pressure. larger orifice equals larger volume and lower residual pressures.
Lower residual pressures my reduce the volume of flow to areas furthest from the pump

 

My truck overheats on the freeway with the tstat out with it in no overheating seemed cut and dry for me.

 

x2 on djb383s comment about what the fsm states personally I would not run any vehicle without the t-stat let alone an engine that can go over 200k when maintained

 

400K maintained 200K by any joeblow who changed oil.

 

And just for those not running a t-stat, a t-stat helps control the temp of your engine. If you're overheating with a properly operating t-stat then you have other problems with your cooling system. It's not the thermostat's fault your vehicle is overheating.

 

Unless it gets stuck closed. For some reason that causes overheating.

 

Hence the reason I said that^

 

you have a obd2 jeep I would not run without a t-stat...