Engine Temperature Gauge Question
 

So I have a question regarding engine temperature and the stock gauge.

I recently noticed my stock gauge is sitting higher than what it used to. See pictures below

Old setting

New setting

Now I don't hold much stock in the gauge but I did go through the ECU to get actual temps.

Highway driving the temp floated from around 179-189 (40/45mph to 65/70mph)

City driving resulted in a bit higher temps 185-196 (Moving including stop and go).

Now when not moving and idling the temp would reach 205, but at 205 the fans kicked in and the temp dropped down to 185 range.

Basically are these within the normal operating temperatures or is it running hotter than it should be. I already did a coolant change, thermostat and radiator cap.

Re: Engine Temperature Gauge Question
 

To me all seems normal. Are you looking at the gauge at a different angle? Seat hight?

There's a dead zone of at least 30 F in the gauge :-)

/T

Re: Engine Temperature Gauge Question
 

Same seat and height. I guess the gauge must be getting old. I might attempt replacing that sensor.

Re: Engine Temperature Gauge Question
 

Young Tom told me that there is a definite difference in the normal operating position of the gauge between OBDI and OBDII cars.

In my 92 pearlie, the normal operating temps put the gauge just below the halfway point, as in your old setting photo.

In my 96 polo, from day one at 42,000 miles, the temp gauge was dead center at operating temperatures. After a head gasket failure, YT installed a new engine at 122,000 miles, and the gauge still read the same and never fluctuated. He said that for some unknown reason, OBDII cars read a little higher.
.

Re: Engine Temperature Gauge Question
 

Hey John,

Thanks for your reply. My svx is a 94 and OBDI. The mystery continues, I am more concerned it is operating within operating specs.

Re: Engine Temperature Gauge Question
 

There seems to be a difference in idle speed between the two..... AC on / AC off (?) - fans run all the time with the AC on.....

The dead zone should "cover" all this, though....

/T

Re: Engine Temperature Gauge Question
 

Really seems normal. When you're idling, there is no airflow over the radiator so the temps creep up, the fans turn on to pull air through the radiator and it cools down. The gauge reading higher is a moot point IMO. As Tapani said, the temp gauge, just as in all other cars, has a huge "dead" zone as otherwise everyone would freak out if they saw their temp gauge constantly moving.

Just keep an eye on things and on cold starts, just double check the level in the radiator.:)

Re: Engine Temperature Gauge Question
 

Thanks Nate, I am kind of set on the gauge being funky. I will stop worrying about it. If coolant starts disappearing I'll be concerned or if the gauge spikes. I just wanted to make sure the gauge sitting higher wasn't a sign of some coolant issue or it running hot. I also might just replace that one wire sensor see if that makes me feel any better.
So anything above 205 constant would be considered out of normal then?

Re: Engine Temperature Gauge Question
 

The AC might have been on the old setting but if anything that should have made it run warmer.

Re: Engine Temperature Gauge Question
 

I recently went through the same thing with my '97 SVX, except it was the opposite... my temp gauge said I wasn't getting up to temp. 1986Nate and Tapani gave me some great direction to track it down. I also changed the thermostat ( and found out that it needs to be installed "right side up"). It was eventually determined by a OBD 2 code reader with a "live data" function that all was within specs. I had basically the same readings as you are seeing, it was the single wire temp sensor that had slowly ( over the space of a couple of weeks), decided to re-calibrate itself.

The idea that the temp gauge has a "dead zone" was a little hard to wrap my head around... but the explanation that car owners don't necessarily want to see it moving around makes perfect sense. Today, virtually all cars use electric fans, which means in traffic, the temp will go up, the fans will come on, and the temp will go up.. and the cycle will repeat. If you're used to seeing it at one specific point ( like you were), you'll pay attention / notice it more if it moves, but for most everyday driving, it just sits in the "dead zone" as the coolant temp cycles up and down with road speed or fan function.

"Back in the day" .. cars commonly used a constantly rotating, engine driven fan, some fixed, some clutched, some flex, but all of them had one thing in common.. They would usually keep the coolant temp fairly constant. A rise in temperature was a definite warning sign.

Personally, I've decided to leave my sensor alone for now, I know from the code reader what gauge reading correlates to what temperature, and I don't mind seeing it go up and down as the fans go off and on. The OBD2 reader sits in the glove box if I ever want to get a second opinion on the gauge reading.

Re: Engine Temperature Gauge Question
 

It turns on both fans at full speed, so not really. ;)

Re: Engine Temperature Gauge Question
 

So after more testing today I have come to the conclusion that it is fine.
Here is some hardcore data for peoples.

Over the course of 1.2 miles there was a elevation increase of 550ft. Temperature (A/C was not on) went from 187-194 climbing the hill. Once the hill was climbed the temperatures went back down to 187-189. (all maintaining 65-70mph).

Another hill was an elevation increase of about 700ft over 2 miles. A/C was on again and I did not go over 194. (Again 65-70mph)

Only thing I will note is that with the A/C on after about 45 minutes of driving coming to an idle resulted in the temps hovering around 196 then downwards after a few minutes. This could also be attributed to cap apparently leaking a small amount going to look into why this is as its a new cap. Going to make sure the PWR isn't causing it to sit too high.

I did change out the sensor for another one I had lying around and it is still sitting at the same spot. I can't explain the change but I will have to live with it. I did see when costing down hill and the temperature reached 178 it went to its old spot. I don't feel the engine was running so efficiently it never went over 178 so I will just assume all is well.

Just in case anyone else notices the gauge sits higher its worth checking data. I did know about the dead zone of the gauge but did not want to make assumptions.

Re: Engine Temperature Gauge Question
 

196 F engine outlet is fine. I bet the thermostat is not fully open if the airflow across the radiator is sufficient. There's a lot of margin for more heat rejection even with the OEM flimsy looking rad.

A temp sensor in the thermostat inlet housing would be nice :-).

The Subaru cooling (or any other system with the thermostat in the engine inlet and one based on high flow rate) can not be approached like the more traditional systems.

/T

Re: Engine Temperature Gauge Question
 

Both gauge reading look normal to me,fans run. Be sure overflow us up and maybe change the temp. Sensor(s) just to say you did.