Thermostat 180.

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Dec 5, 2005
Herndon, Virginia
New car, 2005 Hyundai. 180 degree thermostat. Any chance this thing isn't going to boil off the condensate in the oil, etc, etc?

I thought all the new cars went 190 or 195. Are 180 degree thermostats a new trend or something?

What happened in the computers and emission systems, etc. that 180 is ok?
Nah, it will be fine.
Did you get the 180 spec out of a service manual or did you take a 180 out of the car. Yes, most new cars are 195 or higher. I know of one car that runs at 200+ ( don't remember if it was 206 or 216 ). If you took a 180 out of the car confirm with the dealer that it shouldn't have a higher one it.
Well, I don't have confirmation from the dealer, but Stant and RockAuto spec a 180 for it. The heater isn' quite as hot as my last Hyundai, which was a 195. That sucker was HOTT inside.

Makes me wonder why, is all. They buying some safety margin in an overheat situation? I'm hoping 180 does the trick regarding burning off water from the oil and so on.
i really dont think hyundai would have put a 180 in there if it would hurt the engine. they dont need a bad rep over a little thermostat.

but it is a good question as to why a 180. a cooler engine burns more gas. i dont thing there would be much of safety margin with a cooler thermostat. if the engine was in a situation to overheat i dont think opening the thermostat a little earlier would help a lot, but that is just my opinion on the situation. i could be wrong.
Well, I can't complain about the gas mileage, brand new it gets a little over 36 on the road, no AC. And that's doing 70-80 pretty steadily.

In any case, I'll not be putting a 195 in it, they have to have tuned the computer and the rest for the lower temp. I wish the makers weren't so secretive about this stuff. It would be cool to have the engineers' theory of operation regarding certain aspects of the operation of the engines in these beasts, especially the thinking behind the coolants and oils.

I suppose that stuff is locked up in vaults, never to see the light of day.
Less chance of premature detonation at lower temps? But, maybe coolant temp doesn't really affect combustion chamber temps enough to make a least, not when comparing 180 to 195.
The engines run rich out of the box. I am sure that this is one of the reasons. I would like to see the Elantra tuned to run like a Honda or other lean burn engine and see what kind of hp and mileage can be gotten out of them.
They run rich? How do they clear emissions? Haven't seen any results, but 2005s probably have pretty tight standards to follow regarding CO, and particulate?

I didn't think anything runs rich anymore, but what's one more challenged assumption, right?
Oh, Hyundai, for 2006, put the VTEC on the Accent (they also get about 1500.00 more for the courtesy). And, for that, you get a mush-sprung Accent that gets a whopping five or so more (unusable) horsepower at 6000 RPM.

Under VTEC( Hyundai's iteration is called VTTC, or some such) doesn't the engine management meter the fuel to a pretty lean standard? The 2006 also advertises slightly higher MPG for the automatic, too, I thought that was mildly interesting.

Not thrilling, but interesting. Ok, ok, so it's insignificant, waddya want from me?
The Hyundai shop manual indicates that the initial opening temperature is nominally 180 degrees F., but that the full opening temperature is 200+ degrees F. Don't worry about the horsepower rating at redline - that spec just makes for nice advertising copy. The more meaningful torque curve is broader with the new I4 motor - and includes much of it in the band where everyday driving takes place. I don't always see eye to eye with Hyundai's product planners, but the company's engine people seem to have been given a green light to over-engineer these motors for their anticipated stress level.
Hey Ray! Where ya get the shop manual from? Got a link? I see nothing from Chilton's for a 2005. You're right about the torque curve, it's from 2-4k rpm, quite usable, but the peak rpm is preposterous. Mine is the "old" (2003-2005)one, very smooth, turns a surprisingly low rpm at 70-80, but isn't the Hyundai version of VTEC. Too many changes to the handling, suspension and price took place with the 2006 to make the marginally greater horsepower worth passing up the 2005 GT.

But that's just me.
That only means that 180* is the coolest it will run once it's warmed up. Doesn't mean the coolant won't get to 195* or 200* when you're driving.
TC2Y, you can either order the shop manual for your car from a stealership's parts department (I gave ~$60.00 in '03), or you can access it online at HyundaiWebTech*. If the latter, you'll need Adobe Acrobat Reader installed.

*HyundaiWebTech also lets you peruse and printout the TSBs. (Stealership service department managers hate it when you counter with, "Oh, yeah? Here - read this, Bozo!")
This engine may have odd coolant flow routing.
The 180 may actually correspond to a hotter thermostat in a normal situation.
For instance, Chevrolet reversed the small block water flow in some high perf engines, and needed to use a 180 thermostat to maintain the same cyl wall temps as a 195 used to.
As a side note, some Fords have a regulator on the thermostat, to allow hotter running when cruising, and cooler when full power is needed.
Hot is 225 or so, and warm is 195. Hotter coolant is great for thermal efficiency of the engine.
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