Coolant Temperature Gauge

[byw]

I am new to this forum and just took delivery of a Presara.

I have a question about the coolant temperature gauge and wanted to find out where the needle points to on the dial when the car is running normally after a few kms.

My Presara seems to point to the 9 o'clock position (in the middle of the temperature range), is this normal? My other cars (also Toyotas) seems to point to some where below half way and does not get to half way unless it's overheating.

Looking forward to your responses.

Thank you.

Edited January 4, 2009 by Boof

[Rolla Boy]

Smack bang in the middle or 9o clock is normal for the temp guage...

Any lower and your thermostat isn't closing correctly...

Any higher and you've got bigger issues...

[JIN]

Yeah I am quite sure that is normal.

some other cars may be different like my old car which was honda accord and it pointed at 8:00.

But for aurion middle is 100% ok I guess.

Edited January 4, 2009 by JIN

[DJKOR]

It always amazes me how it can stay so level and consistent. Like even on a hot day when you are pushing it hard and the heat radiating from the engine bay is intense, it still manages to cool sufficiently for the gauge to register in the middle. Just one of those random thoughts that amaze me.

[e240]

Actually, you raised a very good point.

The factory temp gauge is not accurate. Its designed to give a general indication and usually by the time it registers a noticeable change, there is usually something seriously wrong. I guess its ok for the street because you never push the engine that hard for that long a period anyway but for circuit cars, we have additional temp monitoring measuring water temps as it comes out of the engine into the radiator.

However, a mark of a good cooling system is that the temperatures stay within the working range, especially if you only drive on the street.

I actually have a secondary water temp measurement and for most parts, it stays just a tad shy under 80 deg. The hardest I've pushed it on the street see's it go to around 90 Deg, thats about it..and No, the factory gauge did not move a single mm.

It always amazes me how it can stay so level and consistent. Like even on a hot day when you are pushing it hard and the heat radiating from the engine bay is intense, it still manages to cool sufficiently for the gauge to register in the middle. Just one of those random thoughts that amaze me.

[Hiro]

It always amazes me how it can stay so level and consistent. Like even on a hot day when you are pushing it hard and the heat radiating from the engine bay is intense, it still manages to cool sufficiently for the gauge to register in the middle. Just one of those random thoughts that amaze me.

Thats because the cooling capacity of the car is automatically adjusted by the car (through thermostat/thermofans) so that the temperature stays in the right range. The maximum cooling capacity of the radiator + fans running 100% and no airflow has to be capable of keeping the engine within that safe operating range on a stinking hot day, otherwise you'd be having cars overheating all over the place.

And also remember that when you're "pushing hard" ie moving, there is significantly more airflow and thus cooling. Cars overheat standing still (look at F1 cars for instance, which don't have thermofans - they overheat just idling on the starting grid), not on a spirited drive.

[lateralus]

on another note, i had a 92 celica sx with a 5s-fe with 250,000km on it as a first car. the engine never missed a beat, but it always amazed me how sensitive the temperature gauge was.

driving around the suburbs, it would sit just shy of halfway and wouldnt budge. however, as soon as i hit the freeways or highways for a cruise, the needle would drop to around 1/3, and at one point during a drive through the black spur, it dropped to almost cold. although if i stopped and idled, it would be almost as if the engine were still cold as it idled around the 1500-2000rpm mark for a minute or two before slowly dropping back to normal idle speed.

my camry's temperature gaage never budges though

[e240]

Thats because the cooling capacity of the car is automatically adjusted by the car (through thermostat/thermofans) so that the temperature stays in the right range. The maximum cooling capacity of the radiator + fans running 100% and no airflow has to be capable of keeping the engine within that safe operating range on a stinking hot day, otherwise you'd be having cars overheating all over the place.

Only to a point - The Thermostat controls the minimum temperature, and the thermo fan helps keep airflow up during low speed operations.

There will come a point where the cooling system is unable to keep up with the heat, but thats probably only if you drive on a circuit. For road use and even hard road fangs, you are right, the stock cooling system (properly maintained) would be sufficient.

Edited January 5, 2009 by e240

[e240]

on another note, i had a 92 celica sx with a 5s-fe with 250,000km on it as a first car. the engine never missed a beat, but it always amazed me how sensitive the temperature gauge was.

driving around the suburbs, it would sit just shy of halfway and wouldnt budge. however, as soon as i hit the freeways or highways for a cruise, the needle would drop to around 1/3, and at one point during a drive through the black spur, it dropped to almost cold. although if i stopped and idled, it would be almost as if the engine were still cold as it idled around the 1500-2000rpm mark for a minute or two before slowly dropping back to normal idle speed.

my camry's temperature gaage never budges though

With your Celica, that problem is typical of a Thermostat thats stuck open, or half open. Technically, with the Thermostat closed, it would route coolant away from the radiator enabling the heat to buildup.

[Blind Kid Seeks]

on another note, i had a 92 celica sx with a 5s-fe with 250,000km on it as a first car. the engine never missed a beat, but it always amazed me how sensitive the temperature gauge was.

driving around the suburbs, it would sit just shy of halfway and wouldnt budge. however, as soon as i hit the freeways or highways for a cruise, the needle would drop to around 1/3, and at one point during a drive through the black spur, it dropped to almost cold. although if i stopped and idled, it would be almost as if the engine were still cold as it idled around the 1500-2000rpm mark for a minute or two before slowly dropping back to normal idle speed.

my camry's temperature gaage never budges though

With your Celica, that problem is typical of a Thermostat thats stuck open, or half open. Technically, with the Thermostat closed, it would route coolant away from the radiator enabling the heat to buildup.

X 2 my 4AGE did the same thing, and was fixed with a replacement thermostat.

[Soloman]

mine sits just at 9 o'clock too.. Being in this heat up in darwin and me driving it hard.. im surprised i have never seen it above this half way mark...

[PsychoRez]

My gauge is usually below the middle by a bit. But lately its been averaging at the middle and i think i know why. Its usually hot in my country so my AC is mostly turned on. Its only cold in the winter for me.

For some reason its because i don't turn on my AC nowa days, Weather is pretty cold so i don't need to. Of course i was worried when i noticed the needle wasn't in its regular spot. But recently i tried Turning on the air conditioner for a while and guess what, The needle goes below the middle point right back to the usual point.

So i guess its normal.

[NOEL GORDON]

Hi All

I am but a humble Avalon owner and find it a nice car.

The temperature gauge needle sits halfway up the last segment before "90 degrees", around town. On the open road, the needle rises a smidgen so that the needle and the 90-degree mark are virtually as one, with the needle immediately below the mark.

In its 71,000k's the needle has not risen higher.

An engineer friend tells me it all depends on where they place the sensor.

On my early model Falcon, if the ignition were left on after stopping the motor, the temperature gauge needle would climb up the dial, to halfway between 90degrees and Hot.

For what it's worth.

CHEERS

NOEL GORDON

[pegaxs]

It always amazes me how it can stay so level and consistent. Like even on a hot day when you are pushing it hard and the heat radiating from the engine bay is intense, it still manages to cool sufficiently for the gauge to register in the middle. Just one of those random thoughts that amaze me.

The reason it does this amazing feat is because its digital. almost all modern cars have digital temperature gauges. The way they work is the ECU gets a signal from the sensor, works out how to use it, and relays that information to the dash display. you will find the gauge has a tolerance of about 20 degrees where it will not move, say from 90C to 110C. It is more of a step gauge. if you went out and bought an old type temp gauge and put it in the car along side the original one, the analogue one would move up and down as you drove. Thats why everyones gauge sits in exactly the same place on the aurion. If your car over heats, you usually get no real advance warning.. all that happens is the gauge goes from the horizontal to the red section of the gauge and a light comes on and a buzzer goes off. gone are the days of looking and sseing it inch up higher and higher and pulling over to let it cool down. now its basically.. cold, warm, hot, overheating.