is 194 deg too hot for cool weather driving?

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I just installed a Koso so i am watching it like a hawk. temps have been cold here, 20-40 ambient. I mostly see 188 on the highway for short trips. Yesterday i drove it about a hour on the highway at 65 mph, temps about 45 deg outside. It stayed right at 194 deg. My coolant system has lots of PM done. Everything new OEM except water pump and fan clutch. Radiator was replaced by PM but i dont know what type. It has never gotten hot for my by the factory dash gauge. But i installed the Koso just to keep a better eye on it. Is this a normal temp or to warm for the cold outside temp?
 
Sounds normal to me.
 
Normal.
 
I have the factory radiator and run 178*F whether in -10*F or 75*F. Totally stock 96 w/ 285's. Why do I see so many with this high of temps? I have all Toyota replacement parts on a fresh cooling system rebuild and I temp tested my t-stat and it starts opening at 175*F and is full open at 192*F (I haven't got to run it in a 90*+ condition yet.)
 
Efficiency for a gas motor is 190-200
Seems 190ish is norm for the 1fz

Much lower and you get high wear and inefficiency from never warming up
Cold motor is not good either, warm up as soon as possible and live in the correct operating temp is ideal
Hotter and obviously overheating
 
Most gas engines are designed to operate at 190-200 degrees, hot day or cold day.

Diesel engines may have different operating temperatures but the concept is the same - that's why you see truckers with the grille blocked off in the winter.
 
Stock gauge is dumbed down, search temp gauge mod. Where does the Koso pick up it's readings from?

regards

Dave


My Koso will pick up reading close to ambient temps ( +5*) if it sits for a day or two. If it sits for 10-12 hrs it will read slightly higher ( +15* )than ambient.

Edit: At a cold start.
 
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Keep in mind that the purpose of a thermostat is to WARM up the motor. Not cool it. It will cool with no tstat but not warm in cold weather . If the stat is 195 that's what the motor warms TO.
 
Keep in mind that the purpose of a thermostat is to WARM up the motor. Not cool it. It will cool with no tstat but not warm in cold weather . If the stat is 195 that's what the motor warms TO.
Not always the case, some engines will run hotter with no tstat because the coolant is passing through the rad too quickly to efficiency remove the heat...

But agree, that if our tstats fully open at 192, then that's what they were designed to run at...
 
Not always the case, some engines will run hotter with no tstat because the coolant is passing through the rad too quickly to efficiency remove the heat...

Nope, an old mechanics tail. In this case, the system is a bypass type, so with the thermostat removed, some/most of the coolant will go through the bypass, causing it to run hot.

But agree, that if our tstats fully open at 192, then that's what they were designed to run at...

Not so much. The 1FZ has an intake thermostat, bypass system, so the thermostat controls the temp of the coolant entering the motor. If the coolant is say 192F when entering the water pump, by the time it gets to the OBD2 sensor in the head will be significantly hotter, how much depends on conditions, load, etc, but it won't be 192F.
 
My 96 loves 194 degrees per my Ultragauge this time of year. Runs 195.8 on hot summer days.
 
I just installed a Koso so i am watching it like a hawk. ...

This also adds some difference. The ECU sensor is in the head, so measures true head/motor temp, thermostat mode has little/no effect. I said "OBD2" in previous post, that is only significant for those of us who use an ultra-gauge type device to monitor temp.

Aftermarket sensors are often installed in the outlet neck or worse the upper radiator hose, this will read output temp. During thermostat fully or mostly closed, bypass operation there is little/no flow in the upper neck/hose, so will read artificially low, less than head temp. Once the thermostat opens and the bypass is blocked, the reading will more quickly go up and when fully loaded will read slightly higher than the head sensor (output temp is further downstream, has more time to absorb heat).

If you understand the difference, both are acceptable, useful. Directly comparing motors with differing sensor strategies is pretty much useless, so best to compare like data.
 
Last week my Autel gage was reading 80C (176F) going down the highway at 65 mph, but it was -20C (-4F) outside. I found that it was a little low compared to what I recall it normally is which is around 88C (190F). Maybe i should check out the coolant level.
 
This also adds some difference. The ECU sensor is in the head, so measures true head/motor temp, thermostat mode has little/no effect. I said "OBD2" in previous post, that is only significant for those of us who use an ultra-gauge type device to monitor temp.

Aftermarket sensors are often installed in the outlet neck or worse the upper radiator hose, this will read output temp. During thermostat fully or mostly closed, bypass operation there is little/no flow in the upper neck/hose, so will read artificially low, less than head temp. Once the thermostat opens and the bypass is blocked, the reading will more quickly go up and when fully loaded will read slightly higher than the head sensor (output temp is further downstream, has more time to absorb heat).

If you understand the difference, both are acceptable, useful. Directly comparing motors with differing sensor strategies is pretty much useless, so best to compare like data.[/QUOTE

This is very true. Mine is in the rad. hose and i did notice this heating pattern. The coldest tit reads is 32 deg. On the first days i used it the ambient temp was around 20 deg. The Koso would read 32 even after the factory engine temp gauge had started to move. To me indicating that there was not much "warm coolant" leaving the head yet moving to the radiator. Than as it warmed (and the thermostat opened some) the Koso Gauge would very rapidly go from 32 to about 130 if i remember correctly. Then from there it would quickly climb to 160 before slowing its climb to 175-180s. This is a smooth gradual increase in temp once it leaves 32 degrees, but just very rapid initially then gradually slowing gain in temp. Seeing this actually helped me understand a lot about how a cooling system works. But it makes even more sense the way you wrote it. I guess one major flaw would be that if my thermostat was to stick closed, the engine would over heat and my Koso gauge would still read low.

Seeing this it tells me that my Koso gauge will not tell me my engine temp per say, just a MAXIMUM engine temp with the thermostat fully open. With the thermostat closed ( the engine still trying to warm up) it does not accurately reflect the engine temp at all. That being said. I can tell from the Koso when my thermostat is still closed because it is read basically ambient air temp because no warmed coolant is circulating. Which is interest knowledge but i am not sure it is directly useful. I bought the gauge to monitor peak engine temps in the summer. I think it will still be perfectly useful for that. No regrets.

Last summer i drove over Teton Pass heading out of Jackson Wy. The truck was loaded with four of us and camping gear. I tried to take it easy on her and keep my speeds slow. But by the time i got up top you could smell some oil burning. The in dash temp gauge never budged from the middle. This is the only time i ever smelt this. Maybe it was just a few drips of oil seepage burning off. But i made me concerned about pushing the engine hard with out a good temp gauge.
 
seems in the normal range, but a touch high maybe. It has to be hot summer temps before I can get above 190 at highway speeds.
 
You said your fan clutch isn't new OEM; how old is it?
I've made some posts about my seemingly fine fan clutch that really wasn't. I got flamed a little regarding safety, but a rag on my hand proved to me that the fan wasn't locking up at temperature.
 
My truck runs about 179-183 here in the AZ winter. Last summer it ran at 195+ all the time, with the occasional climb into the 220s while under heavy load. Since then I have changed the coolant, WP, T-stat, all the hoses and the fan clutch mod. I'm eager to test the new system in the normal ambient temperature of 105F, common here in the summer months.
 
I got flamed a little regarding safety, but a rag on my hand proved to me that the fan wasn't locking up at temperature.

Been doing the 'fan grab' for years but, always checked it rotated by hand before starting the engine, then as you say gently drag it to a stop with your hand protected, no flaming from this direction LOL.

Back to post, as I am at the moment compiling a list of engine running temps for a project on my own car it seems that 190 - 210 is about right. Even when the water is coming out of the head at that temp it is not close to boiling because the system is (should be) pressurised.

regards

Dave
 

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