OK I know this is a basic thing but I dont want to pull my thermostat for nothing.

 

I would say yes, bad Thermostat.


And does your mileage read under 10,000 miles?????
If that's the case, the thermostat shouldn't be bad.

 

With so few miles that is rather strange.

I have TRD T-stat and use Redline WaterWetter and I can get mine going over the space of one notch like yours only when I am going super fast on a cold night on a highway, but when my vehicle was younger and stock, hardly ever moved regardless of my driving habits or air temperature.

 

Naw man. I got 61,000 miles on it. That's just a good cluster pic I snatched off the forum to illustrate my point.
When I got the car running after the full swap it was hot as hell outside.
So it looked normal to me. But now it's getting chilly at night and the motor never seems to fully warm up. I'm going to get a new thermostat from toyota.

 

is mine bad? mine is always at the 2nd line down from the red. so i would say its at the 2nd line from the top even in chilly weather.

 

I've got the same problem, with 260+k miles on the SC400. It never gets to full op temp and therefore runs rich; I'm down to about 19.5 mpg. Low coolant level or bad thermostat, or both?

 

I deleted my hydro-pump and went with dual electric fans a while back, this altered the sensor reading and my car constantly runs just a hair over the 1/4temp mark read on the cluster, never moves....I have heard running the engine even slightly below normal operating temperature promotes premature engine wear and potential loss in performance....

Does anyone have any insight into this?...I would think with a cooler running engine block, less heat and friction would occure, which I would have thought would promote less engine wear....Anyone?

 

No way man, most engine wear happens when the engine is below normal operating temperature. That's why an engine that suffers a lot of cold starts to do 5-mile trips will wear faster than one that goes on much longer highway drives.

 

Cloud9 is right...some. The short trips that don't let the engine warm do cause accelerated wear due to the block and etc. not being fully expanded. The majority of the wear that operation below normal op temp does comes from the OIL. Simply operating your engine causes water to be introduced into your crankcase. With properly warmed oil the water is evaporated out of the oil quickly. Also present in oil is sulfur. Let sulfurated oil sit with water and you get weak solutions of sulphuric acid. That eats little pits in the bearing material. Got the picture? Bad, huh? If there ever was a case for full synthetic oil it is that it has no, as in none, sulfur in it. Does get a little from the combustion chamber, however, so you have to change it at extended intervals. Remember a while back the fed created a stir with a requirement for "low sulfur diesel"?

I can't believe you guys are paying such close attention to the dash temp gage. It is a crude and uncalibrated device that shows you relative and approximate data. Measure the temp of your water and then "NOTE" what the gage says. Our engines have aluminum blocks and that metal gives up its heat easier than iron. My thermostat works OK but on a really cold day my gage reads a half a division lower. Running at 90 for 10 minutes on the dessert in summer will give me a half increment increase. I think our cooling systems are very stout and unless there is a failure they will keep the engine far below any damaging high temp.

I sure agree with the thought that it is a good idea to replace the thermostat with a Lex OEM item. I have looked at a ton of thermostats and I have NEVER seen one as comprehensive as what is in my SC400. It might be super spendy and that means you need Gazi.

If you are not running FRESH high grade antifreeze, well, your nuts. The aluminum in the cooling system is dissolved by fresh water. Remember the HORROR STORY about replacing the heater core and how you should junk the car if that happens? Fresh water! When you add antifreeze you should never dilute it with tap water. Distilled water, ONLY.

You can put your mind at ease by having your OIL and COOLANT analyzed twice a year. That will tell you how your oil and coolant are working and what problems are creeping up. Reminds me, need to do that myself.

Good luck and my apologies if I got on a high horse.

John

 

Most of what John said is true. But, in areas where it is now getting cold and the engine never gets up to full operating temperature, the temp gauge is another graphic reminder that one is freezing one's butt off. So, to get back on topic, I replaced my thermostat and everything is back to normal! Toasty -yeah!

 

I was told to think "Thermal expansion"

Cold engine - large gaps - loose engine
Hot engine - small gaps - tight engine

Also on these SC4's when running the engine slightly below normal operating temps the ECU compensates a richer fuel mix which promotes faster ring wear over time... The compensated ECU fuel mix when ran colder makes the car feel more responsive and crispier to the feel... But then again, running the motor leaner I always thought gives you more power...I am just forwarding info I have read...Does that all sound right?