My 2014 JK Rubicon with 50K miles was throwing off a check engine/malfunctioning thermo code. I am having it replaced and the shop is telling me factory recommended 203 degree thermostat installation. Why so hot? Shouldn't it be 180 degrees?
203 degree thermostat?
- Thread starter Nericson
- Start date
My t-stat is a 208. 2015 Willy's. I've heard of some people putting in a 180 and throwing a P0128 code.
My 2014 had a P0128 code (engine coolant not at thermostat regulating temps) a few years back and discovered it was stuck open. I wouldn't assume that in your case as it could also be a faulty sensor or an ECM fault.
So, your engine heats up to somewhere around 195-205 and the t-stat springs into action, allowing coolant to flow through the engine. If your engine is not getting warm enough because of a stuck open t-stat, it's very easy to diagnose. Simply cold start your Jeep and wrap your hand around the upper radiator hose. If you're feeling coolant flowing through the upper hose almost immediately, you have a t-stat stuck in the open position and it needs to be replaced. Unless someone else changed it out at some point, the OEM t-stat is supposed to be a 203.
I also discovered this is not a part I could find anywhere within a hundred miles, so I ordered it from https://www.partsgeek.com/catalog/2014/jeep/wrangler/cooling_system/thermostat.html
It's a very easy driveway fix that'll take you less than 30 minutes, Will take you longer to fill & burp the radiator when you're done. But, I'd certainly diagnose it as I explained above first. No sense paying a shop a couple hundred in labor to install a $22 part only to discover it's not the problem.
Why "should it be" 180°?
Engines are designed to run at a particular temperature, balancing latent heat, compression, efficiency, etc. OEM is 203° and is what I would stick with. Lower temperature thermostats only regulate the MINIMUM operating temperature, not the maximum anyways.
Yeah it's a definitely a balancing act. The coolant needs to spend enough time in the engine to absorb and enough time in the radiator to release. Too low of a stat and it won't stay closed long enough, too high and it won't stay open long enough.
I should have said seems like it should, not should. I have a GM 3.6L in another vehicle and it runs consitently at 183 degrees after it warms to 180. So I was making presumptions about 3.6L V6 engines and not sure why one would need to run hotter than another.
Apparently. The Chrysler engine has had 3-4 times the maintenance/fix it costs, and has 1/2 the mileage on it as the Chevy.
You think the Jeeps have alot of problems you should see how bad the newer Dodge diesel trucks are.
Dodge trucks, in general, are mechanic-rated as one of the most difficult vehicles, import or export, to work on.
Higher operating temperatures lead to a slight increase in the risk of detonation (it's also called premature ignition, but if you say things like that around car guys, the conversation gets off track really quickly because we're all 12 years old in our hearts.). Detonation is bad. As in, potentially destroying your engine bad. So you have to back off on the timing and change your Air/Fuel ratio, both of which will decrease power.
Is the power difference much? Not really. Not enough that your carefully calibrated Butt-O-Meter will notice. It's worthwhile to consider a lower T-stat (with corresponding adjustments to the fan settings) in a max effort race engine. I doubt many (if any) of us are running that sort of engine in our Wranglers. I run a 160 degree t-stat in my Corvette. But that's a forged/heads/cam/blower LS3 making about 850 HP.
Yeah, different theories apply when you start significantly increasing heat rejection and/or have a purpose built vehicle that spends much if it's life at specific operating points.
It’s all about the design. Most cast-iron blocks do best in the 195-205° range. Aluminum blocks, aluminum heads, phenolic intakes, etc. do add some variables to that, but generally, all gas burning engines typically operate in a ~20° range of each other (note that water jacket temps aren’t always 1:1 with combustion chamber temps). You’re balancing cylinder pressures with latent heat for the best combustion efficiency. The hotter you can make a cylinder/engine run while avoiding detonation is a well-known approach for getting maximum power across the operating range, while also getting the highest fuel efficiency.