Radi

I think that's my stapler too!

extrashaky

bigbadon

1: thermostat's job is NOT to cool the engine.
2: The thermostat is there to speed up and get engine to proper operating temperature.
3: If temps go above 210 and if thermostat is functioning normally changing to a 180 thermostat will accomplish absolutely nothing, engine will still overheat! Look elsewhere for the problem.

Rogue4x4

Props to SteveMongr

Basslicks

4: to keep coolant evenly distributed throughout the engine block.


To BlueJeepGuy or whatever your name is....

OEM spec is 195* (or 190*)... the ECM will keep the engine management system in open-loop and the air/fuel mixture will be perpetually stuck on fuel rich until it sees the engine is up to a minimum 210* consistent. Therefor, if the motor is running correctly and the cooling system is up to spec, you should see a consistent 220*F (10* buffer to keep the ECM from switching to open/closed constantly). That's the way AMC designed it from the get-go. Apparently it worked because Chrysler pumped out umpteen million units all the way up until 2006 when the last TJ rolled off the line with a 4.0 liter L6 in it and guess what... it still had a 195* thermostat in it.

You go ahead and run whatever you like. My jeep had a 160* thermostat in it for at least 5 years because I didn't know about it. Ran rich the entire time and I couldn't figure out why - until I realized the temp gauge was never going above about 180*. Replaced it with the correct thermostat and it's made a big difference.

JimmyBo1313

Interesting Very Interesting...I found this through a search looking to solve the age old question of stat temps and what was best. I got more than I bargained for and very entertaining. My summation is 195*. I was hell bent on 180* seeing that I live in SC and plan on some low and slow mud when I get done. But out of the technical info I found every problem making my ZJ run hot. Fan clutch crappy, radiator disintegrating and clogged with its own matter and not so good fluid. My 96 ZJ my sister bought new in Ohio, she exported it about 7 years later to Scotland for about 8 years and then brought it back to the states were it has sat in my warehouse for the the last 6 years or so accept for a yearly visit from Her and a jaunt out west to see family. She gave me the Jeep about a year ago and I've been doing this 3" lift thing after driving it for a while when I first got it. It is amazing what moisture and salt can do to a radiator. I would have never seen it if I hadn't taken the metal support off the top to address some surface rust. I bought a radiator from DPG yesterday. Unfortunately the all aluminum 3 core is discontinued so I got the 2 core polly and aluminum. I'm in the process of ordering a
GMB 920-2020 fan clutch severe-duty
GMB W0133-1623612 water pump
Going to use my 7 blade original steel fan
I guess if your systems aren't cooling correctly dropping the stat temp would only mask the problem if that.
And now a 195* Stant thermostat

kemjeep

thanks for the post & pics. just goes to show how important common sense is, and how important an up to date & maintained cooling system is especially on our jeeps ps dont forget about the radiator cap my 2cts.

JimmyBo1313

I'll be dog gone if I didn't forget the cap. Thanks

NebCherokee

So, here's the run down. The engine warms up... preferably to around 200-210 degrees. This does provide less wear on engine components. At that temperature with the proper engine oil, the viscosity of the oil is where it needs to be to prevent additional wear and tear. So... getting a 195 degree thermostat is optimal, considering you're not running anything else but a stock motor and using the proper oil recommended by the manufacturer. So when the engine temperature gets above 195 degrees the flood gate (thermostat) opens and coolant is circulated through the head via the water pump. The water pump constantly spins whether that Tstat is open or closed. It continually circulates coolant keeping the system pressurized as the fan spins and pulling air through the radiator to cool the coolant. When that Tstat opens after the engine has warmed up enough the electric fan kicks on to help cool the hot coolant that is being circulated through the head and back through the radiator. Once the coolant is cool enough the TStat closes allowing the coolant temperature to rise again. That is called a cooling cycle. Every engine in a car does that numerous times. This is why coolant temperature is never consistantly remaining the same. What people may care about is if they add performance enhancers to their vehicle such as a supercharger which often times introduces more heat in a shorter period of time thus requiring a lower Tstat often times to keep temperatures within their optimal range. Unless you're Supercharged or have other performance mod that are introducing more heat into the motor you should be running a 195 degree thermostat. 180 is the lowest anyone should run. Definitely not if you want hot air during the winter time. Perhaps if you live in Arizona or Death Valley then go for the 180. Other than that if you're having heat issues your problem is with a faulty component. Don't push off replacing that faulty part because you think you're going to trick the system by putting in a lower thermostat. You're going to run into bigger problems down the road. Also don't forget fan shrouds were made for a reason. No, not to protect your hands dummies. They are designed to help the fan pull/push air through the radiator. I hate seeing all these shadetree mechanics who supposedly worked on cars all their lives and don't know an effing thing still. It's because those folks never went to school to actually learn about it. They think a Chilton's manual is all they need, come on here acting like they know a thing or two, and give bad advice. Probably because they don't know better or they are accustomed to not fixing something right the first time, or both. Someone please correct me if I'm wrong, but that is the basics of every modern cooling system. Now there may be a few different components here and there like a fan clutch or accumulator seen in older jeeps.

RocketMouse

nice post...but don't know if you realised that you just resurrected a thread from the dead. lol

Basslicks

lol... this, but at least the information was correct.

I will say, it was a little derogatory and subjective though. Not everyone who didn't go to ASE or trade school for auto mech is a complete idiot. Some of us get our education from taking advice from good mechanics, reading whatever piece of trusted automotive literature we can get our hands on, and other sources of credible information.

I for one knew about the purpose of the fan shroud since before I could drive.... and I've still never taken a single credit hour of an automotive technician or diagnostician course.

cruiser54

I never took auto shop either.

When hiring technicians at the Jeep dealer back in the day, the guys just out of "tech school" were big on theory and small on practical knowledge and experience.

Basslicks

Wish I would've applied back in the day.... I haven't tried any mom-n-pop shops, but the "big name" shops all require at least 1 ASE cert.