[svskyus]

Once the engine warms up, dash thermometer on my '19 Limited never varies. It is always exactly in the center. Pulling a trailer up a long hill in 100+ degrees with fan roaring, right in the center. Coasting 7 miles downhill from the ski area in zero degrees, right in the center. Is this normal, and if so, why even have the thermometer?

 

[DocRock]

Once the engine warms up, dash thermometer on my '19 Limited never varies. It is always exactly in the center. Pulling a trailer up a long hill in 100+ degrees with fan roaring, right in the center. Coasting 7 miles downhill from the ski area in zero degrees, right in the center. Is this normal, and if so, why even have the thermometer?

I believe you mean the temperature gauge never varies once it's warmed up.

 

[lians60]

This is normal. Fluctuations in the temp gauge would actually be a sign of an issue. The purpose of the gauge is to make sure that the temps are where they should be - in the middle.

 

[svskyus]

Of course the "temperature gauge". Long day of skiing.
Every other vehicle that I have owned that had a gauge showed quite a difference from hot uphill travel to cold downhill travel. My Mercedes Sprinter goes from 180 to 218 degrees and back on every hill, for example. I Know the temperature of the Ascent engine changes, as the fan comes on when it is working hard. I am sure that if I installed a ScanGauge II, it would show significant temp changes. Does everyone's gauge stay exactly in the center? No biggie, but kinda like to know when car is nearing overheating.

 

[redscreen]

Every Subaru (4) I've ever owned has warmed up and sat smack in the middle of the gauge no matter what happened. Cold, Hot, sandwiches. H6, 2.5NA, 2.4 Turbo, 2.0NA, its one of the things I love most about Subaru's after having endured overheating and horrible water cooled systems in other cars for decades.

 

[hokiefyd]

Modern temperature gauges are not intended to be accurate representations of coolant temperature. They will generally read "in the middle" for anything the manufacturer considers to be "normal" temperature. This is very likely because people will mistakenly think something is wrong with the car if the temperature gauge moves around a lot. The coolant temperature will fluctuate quite a bit during normal driving, but a moving gauge worries some people. That said, it WILL move up to the hot zone if the coolant becomes dangerously hot -- with enough time for you to be able to to something about it (like pull over, etc.) before the whole thing melts down.

You can do a few things about this, or to make yourself feel more comfortable:

1. Add the oil temperature chiclet as one of your dash-top monitor "favorites". This actually IS a digital temperature indicator that will vary quite a bit. Oil temperature is generally a better indicator of how much heat an engine is generating than coolant temperature, because coolant is actively cooled by the radiator and there's more cooling capacity built-in to the system than the car needs. Even pulling a trailer up a long hill, the car won't overheat unless something is mechanically wrong. As noted above, the gauge will indicate a problem to you before it's too late to correct it.
2. Buy an inexpensive Bluetooth OBD-II reader and monitor coolant temperature directly with a smartphone app. You can read the coolant temperature parameter directly and make some mental notes to yourself about gauge positions and what coolant temperatures they generally represent. I haven't done this myself, but I'm guessing that "dead middle" on the gauge could be anywhere from about 185 *F to about 220 *F.

 

[Robert.Mauro]

The temperature gauge is pretty accurate. Run Torque for Android or some other tool that'll get the temp from the ECU. Your Ascent will be running at about 195° virtually all of the time, even under load, or in the middle of the desert off roading.

Oil temperature and CVT Fluid temperature will change, but it's ridiculously rare for engine coolant temperatures to move more than 5 degrees, if that much.

 

[Trey T]

Of course the "temperature gauge". Long day of skiing.
Every other vehicle that I have owned that had a gauge showed quite a difference from hot uphill travel to cold downhill travel. My Mercedes Sprinter goes from 180 to 218 degrees and back on every hill, for example. I Know the temperature of the Ascent engine changes, as the fan comes on when it is working hard. I am sure that if I installed a ScanGauge II, it would show significant temp changes. Does everyone's gauge stay exactly in the center? No biggie, but kinda like to know when car is nearing overheating.

Depends where the coolant temp sensor is located, before or after the radiator. For the coolant reading to be constant, the sensor must be after the radiator. The sensor for FA24 (gasoline engine) is near the intake, which is after the radiator. How about your Sprinter?

You said "exactly in the center" .... well, the analog gauges may not be precisely at let's-say-195degF all the time but it does fluctuate a bit like several degrees if you use a digital guage.

Finally, something to think about: ideally, you want your coolant reading to be constant because you want to compensate significant fluctuation of engine oil temp. My Limited MFD will show 195-215degF in the summer.

 

[Robert.Mauro]

Just to add to @Trey T's excellent post, we have absolutely zero true analog gauges. Every gauge in the Ascent is a digital gauge (with a simulated analog representation) run by the computer via digital data being used to set needle positions. It's actually been like that for over a decade. It's why our gauges, just like the ones on this decade older Subaru, are able to do this "Subaru Start Sweep"

BTW, you can actually turn that on and off in the settings using the i/Set control on the steering wheel, when the car is in park.

Various other cars of various years have actual mechanically/resistance/direct current driven true analog gauges, but, the Ascent isn't such a car. The difference being, instead of a thermistor being wired to a needle's coil in the dash board (a truly analog gauge), our temperature sensors all go to the computer, and, the computer tells the gauges what to do. It's why the output representation is always as accurate as what the computer thinks is going on, in conjunction with which vehicle sensor is being used.

Side note: the Ascent has a bunch of temperature sensors throughout the drivetrain.

 

[hokiefyd]

You can get an idea of the coolant temperature based on the cooling fans operation, at least if you don't have the A/C on (air conditioning compressor load will also control the cooling fans, independent of coolant temperature).

From service data, the cooling fans will turn on at about 50% at 208 *F and then will turn back off if it cools down to 205 *F. If the fans are on at 208 *F and the temperature continues to rise, they'll go to 100% at 214 *F. And they'll stay on 100% until it cools down to 212 *F, when the fans will drop back to 70%. Then they'll stay at 70% until they turn back off at 205 *F. Again, the fans are pulse width modulated, and they'll respond to either coolant temperature OR the air conditioning load. So, if your A/C is off and your cooling fans are off, you know your coolant temperature is under 208 *F. If your A/C is off and your cooling fans are on, you know your coolant temperature is at or above 205 *F.

We recently took a drive on Skyline Drive (from the Front Royal entrance) and it was kind of a slow crawl to the top of the mountain up to the visitor center. The cooling fans were screaming by the time we got to the top, but the needle hadn't moved. I noted it because it's the first time I had heard them on what seemed to be high speed. So I guess the coolant temps had climbed up over 214 *F on the climb up. It was about 30 *F outside that day, so I know the load was not from the A/C system.

I imagine the needle would start to move higher if the coolant temp goes up beyond about 220 *F. Because at that point, it's sort of in a runaway condition unless you modify the operating environment. The fans are already on their highest setting and the thermostat is already wide open. If it keeps climbing much beyond 214 *F, then it should just continue to climb unless you remove the engine load, etc.

 

[Robert.Mauro]

The needle will move before that. Sadly, I blew my head gaskets on my 2010 Outback at about 180,000 miles, and, watching data via Torque, I could see the needle move in direct relationship to temperature increases.

 

[hokiefyd]

That's a sad day indeed (head gasket failure)!

 

[Robert.Mauro]

That's a sad day indeed (head gasket failure)!

I so ridiculously abused that car that I am not surprised. I drilled out the bottom of the thermostat and drove another 20,000 miles until I finally got the gaskets replaced.

 

[vitenite]

On that note, what should be the normal operating temp? I get it to about 198, driving under easy conditions and it goes up to 212-215 under heavy acceleration (uphill climbs...) fairly quickly.
Strangely, using manual trans to downshift for downhill slowdowns does not result in temps shooting up...

 

[Robert.Mauro]

On that note, what should be the normal operating temp? I get it to about 198, driving under easy conditions and it goes up to 212-215 under heavy acceleration (uphill climbs...) fairly quickly.
Strangely, using manual trans to downshift for downhill slowdowns does not result in temps shooting up...

That's about where my oil sits, except during some of my most extreme driving.

 

[denissh]

Many cars now days have Temp gauge stay in the same spot from ~175 to ~215 .... aka "normal" operating range ...
if it start moving you may have a problem ...

 

[hokiefyd]

On that note, what should be the normal operating temp? I get it to about 198, driving under easy conditions and it goes up to 212-215 under heavy acceleration (uphill climbs...) fairly quickly. Strangely, using manual trans to downshift for downhill slowdowns does not result in temps shooting up...

That sounds very normal. Especially for systems with electric cooling fans that may not be on all the time, the coolant temperature can actually vary quite a bit. If it's a cool day and you're not running the A/C, your cooling fans may never come on -- as long as there's enough airflow through the radiator to keep the coolant at a good temperature. If you sit parked with no A/C on, the coolant temperature will start rising and will continue to climb until the fans kick on. Then they'll cycle on and off from there.

Temperature should not rise with downshifting for slowing down. Engine speed itself is not the main driver of coolant temps (because the engine is making very little power at closed throttle).

 

[svskyus]

Original poster here....
What I have learned from the comments here is that the temp gauge doesn't give you any useful information until the engine is about to seriously overheat. Otherwise it stays at dead center thru a wide range of actual engine temps.
If you want to know what temp the engine is running at you need to:
1. Learn the on/off temps for the various fan speeds, and keep your music low
2. Install a scangauge II and set engine temp as a parameter
3. Set oil temp as a dial in the small screen above the radio, and keep cruise control off so you can see it. Learn safe range of oil temps.

So really the temp gauge is useless. I stop looking at something that remains static even tho the conditions it monitors change. I would stop looking at the spedo if it constantly read 55mph regardless of my speed, only to move if I exceeded 90mph.

I get a large warning on my screen if my windshield washer fluid is low. Can I assume I would get a similar warning in an engine overheat situation as well? Basically a digital idiot light?

Bottom line, I would like the gauge to warn me if I am getting close to a problem, not just when the problem occurs. End of rant...

 

[Robert.Mauro]

If your gauge does that, it's not operating correctly.

 

[hokiefyd]

Can I assume I would get a similar warning in an engine overheat situation as well? Basically a digital idiot light?

Your owner's manual has information on how the car will warn you of a condition that you need to be aware of. Your temperature needle should begin to warn you if the temperature climbs above the normal operating range, and you'll get additional lights and indications if the condition worsens to the point where you need to take action.