Thermostat ?????

[jdub]

good deal.. i was always told 160-180*t-stat is what you want? isn't it better to keep your engine cooler?

You were told wrong
The thing is, a lower temp stat will not keep the motor cooler unless excess thermal transfer capacity exists...i.e you have a bigger rad providing additional coolant volume and greater efficiency to facilitate heat removal.

This is not necessarily a good thing. On a stock rad, the coolant will delay warming up to the 176 degs the TCCS is looking for to come out of warm-up enrichment. You will run rich for a longer time (gas mileage) until ops temp is reached. If you have a big rad with a 160 deg stat, it's possible you will never hit the 176 degs the TCCS is looking for...you will never reach ops temp.

The ops temp range is 176-210 deg...this is normal and what you want the cooling system to do. A 190 deg stat is good for 99% of the 7Ms out there. The exception is parts of the country where it's hot as blazes (like Arizona) in the summer...the Delta T between OAT and coolant temp greatly reduces efficiency. In this case a 180 deg stat will help the system get a "jump" on cooling....max coolant temp will still depend on total thermal capacity. I would never use less than a 180 deg stat.

FYI - above 210 degs, the TCCS starts to pull timing.

 

[noel]

well as stated before im running a 190* theremost with a OEM Rad. The neddle in the gauge is not halfway[middle] it's like 3-4 lines under that middle line...why does my gauge read alil cooler beats me i have no aftermarket Cooling systems all OEM

 

[jdub]

The stock cooling system has excess capacity
It's designed to keep the coolant close to 190 degs...just like yours does now. The stock temp gauge pointing at 4 o'clock is just about perfect and what you would expect on a stock system. BTW - I am glad it was the stat...that is a good thing.

Previously when you saw 1/2 to 3/4 scale on the temp gauge, you were overheating.

 

[suprafanatic]

ok, well thanks for the helpfull info. my car has a 180* in it at the moment. so i guess its ok. i guess the reasoning behind what i was told is that the cooler things are under the hood the more power you will make..

 

[jdub]

ok, well thanks for the helpfull info. my car has a 180* in it at the moment. so i guess its ok. i guess the reasoning behind what i was told is that the cooler things are under the hood the more power you will make..

It's reasoning that has no basis in fact. Colder intake charge air, sure...lower coolant temps, ummm no. Now that you know, you can pass along the correct info next time you "hear" someone make a statement along these lines

 

[eman2289]

Thanks Jdub, I was always told the same thing about cooler= more power. Never really understood it, but now I know why.

 

[suprafanatic]

ya, i will diffintly pass the word on. thanks!

 

[MA70witBoost]

get an oem one. go to toyota and buy it from them. its like 20 dollars (i think im exagerating) and its better than the crappy pep boys one. i put one on my 7m because it had a gutted thermostat. the new one lasted me 3 weeks befor it stopped openning and blew my head gasket. aftermarket thermostats ftl!

 

[jdub]

^^^ The exception is the Stat SuperStat

If you guys are getting rust, stat jamming up, etc...you might want to take a look at the last time you flushed/changed coolant...every two years is a good schedule. You want to run at least a 50/50 mix coolant to water...colder climates 60/40. Coolant is not only anti-freeze, it also has rust inhibitors the system needs to function properly.

 

[black89t]

don't forget distilled water. its only a couple bucks and makes a HUGE difference with corrosion in the system.

and the guys at toyota just like any other car company did a TON of reseach to get everything on the entire engine to revolve around that 190 them stat. i wouldn't mess with it.

good thread for newbies.

 

[black89t]

jdub how many of us can even go two years with out pulling the motor for some sort of mod. ROFL.

just joking.

 

[jdub]

LOL...or, pulling the motor for "other" reasons

 

[Who]

This is topic is pretty basic compared to others but it just got complicated for me. The TSRM shows a test for the thermostats and it gives you a range of 187-194F to be within specs. We all agree that the OEM stat rad should be 190F..I've called, Advance auto, Napa, Bennett Auto Supply and Pep boys concerning thermostats for the supra. They all sell 180 or 195 degree stats. All four shops tell me that the 195F is the OE stat and the 180 was the alternate. I called my local Toyo dealer and the parts guy gave me a price ($28) but he couldn't tell me what the stat temp was. WTF
If I use a 195F stat I figure the operating temp could never be below 195F due to the thermostat closing. On the flip side if I had the perfect efficient cooling system my temps could be as low as 180F. I guess I will play it safe and use the 180F considering my climate.

On another note the tsrm shows that the condenser fans turn on if the coolant temp goes over 210F. Condenser fans that run when your ac is off should be a warning or a alert to a overheating problem. Feel free to correct me if I am wrong.

 

[Poodles]

BINGO, yep, the stock aux. fans are supposed to kick on in an overheat situation. They have their own circuit and sensor as well.

Stock t-stat is marked 88C, which comes out to 190F...

 

[jdub]

The condenser fan is controlled by water temp sensor #3 and functions at 203 deg F
The aux fan(s) are controlled by water temp sensor #2 and function at 225 deg F
http://www.cygnusx1.net/supra/Library/TSRM/MK3/manual.aspx?S=AC&P=33

Both switches are on the thermo housing.

The Toyota stat is 190 deg F. I've tested several different thermostats...boiling water with a thermometer. I've seen +/- 10 degs F on them, including OEM. The 180 SuperStats tended to start opening at 185, full open at 195...the Toyota OEM was almost identical, but full open at just over 190 (opened faster). The 195 SuperStats didn't go full open till almost 200, but started opening at 190.

This variance is another reason I cut the jiggle valve off
I also test a brand new stat before I install it...I've returned them (including OEM) because they did not open correctly.

 

[Who]

The condenser fan is controlled by water temp sensor #3 and functions at 203 deg F
The aux fan(s) are controlled by water temp sensor #2 and function at 225 deg F
http://www.cygnusx1.net/supra/Library/TSRM/MK3/manual.aspx?S=AC&P=33
Both switches are on the thermo housing.

I got my info from the second paragraph in the provided link. My vehicle is a 7mgte A/T. It seems that my 210F-212F temp quote only applies to the 7mgte A/T. Just wanted to let you know I did some homework and I didn't pull the numbers out of my arse. In any case I could still be wrong. MK3 TEWD

Toyota stat is 190 deg F. I've tested several different thermostats...boiling water with a thermometer. I've seen +/- 10 degs F on them, including OEM. The 180 SuperStats tended to start opening at 185, full open at 195...the Toyota OEM was almost identical, but full open at just over 190 (opened faster). The 195 SuperStats didn't go full open till almost 200, but started opening at 190.

This variance is another reason I cut the jiggle valve off
I also test a brand new stat before I install it...I've returned them (including OEM) because they did not open correctly.

Great Info and you saved me $15.00 I was going to buy both superstats and test them in the water pot per the TSRM.

 

[jdub]

Ahhh...the TEWD shows the off temp from page AC-33.
I didn't figure you pulled the numbers out of your arse...the temp specs from AC-33 are what's used to actually test the switches. Thought I might as well post the aux fan temps too

For where you live (South FL), the 180 stat would work well. I'd still test it though!

 

[MA70witBoost]

^^^ The exception is the Stat SuperStat

If you guys are getting rust, stat jamming up, etc...you might want to take a look at the last time you flushed/changed coolant...every two years is a good schedule. You want to run at least a 50/50 mix coolant to water...colder climates 60/40. Coolant is not only anti-freeze, it also has rust inhibitors the system needs to function properly.

i was running full 50/50 w/ redline water wetter in my koyo radiator.

 

[jdub]

A heads up - Redline Water Wetter can react with certain coolant chemistry and cause a kind of "slime" to form. I did on mine using Toyota Red coolant. It is mostly for use with straight water on a track car.

 

[MA70witBoost]

A heads up - Redline Water Wetter can react with certain coolant chemistry and cause a kind of "slime" to form. I did on mine using Toyota Red coolant. It is mostly for use with straight water on a track car.

Know anything about prestone 50/50? thats what i was using