96' legacy 2.2 l wagon, auto 97,000miles

 

So ever since I got this car about a month ago my temp gauge has not worked properly.  It almost always stays below or even with the C, and will occasionally climb about a 1/4 way between the C and the half way mark.  I replaced the thermostat with a Subaru one about a week ago(the one I pulled out was aftermarket), and just replaced the coolant temp sensor today, with no luck.  the only change I noticed was that with the old aftermarket thermostat the temp gauge would sometimes climb to normal operating temp(just below the half-way mark) but go back down after a minute or two and now it never gets above 1/4 way up.

 

When I drained the coolant to do the thermostat I just pulled the plug on the bottom of the radiator and didn't remove the cap or bleeding screw, then pulled the lower hose to drain the rest.  When refilling the coolant I just popped off the cap and added about 3/4 gallon tell it seemed full, then started the car and pulled the bleeding screw and let it run like that for 5 minutes and put it back in and went for a test drive.  The next morning it was low on coolant so I pulled the cap and bleeding screw and added tell it seemed full.

 

Then I searched for info on burping the system.  so that night I parked on a hill, so the coolant could drain into the engine.  The next morning I started the car up pulled the cap and bleeding screw and added until full, about a quart. Repeated this the next night/morning, but only added about 1/2 pint.  Some drained out while replacing the temp sensor, so I jacked up the front end as high as it would go, started the car, pulled the cap, added fluid, then pulled the bleeding screw and added fluid until it was sort of fountaining out of the bleeder hole, put the bleeding screw back in and the cap back on.  went for a test drive, and nothing changed.  I don't feel comfortable driving it not knowing what is going on with my engine temp.

 

At this point I'm stumped, and probably going to take it down to the mechanic.  Unless there is something else I can try?

 

you probably have a butchered T-stat.

 

when the head gaskets go bad, you can keep it from overheating by punching the guts out of the t-stat and reinstalling it.

drive the car for a while, long enough to bring it to full operating temp and then look for bubbles in the over flow bottle.

bubbles would be an indicator of bad head gaskets.

this is just a guess.

 

but if you install a subaru stat, these cars do not like after market stats,

and find the one in the car has been altered or is missing, you will know.

Remove the upper hose from the radiator side and fill the block there. If it takes on coolant, you would have had an air pocket. This is what you would have wanted to do when you originally serviced the thermostat.

 

How does your heater run. If it seems cool, that would be indicative of not enough volume of coolant.

I would remove the lower hose from the block to take a look at it. Have a new Subaru brand replacement T-stat at hand. Compare what comes out, with the new one to put in. Odds are, you will install the new T-stat.

Maybe the gauge itself? is there a way add an aftermarket temp gauge?

 

I put in a new Subaru thermostat( the old one was aftermarket, but not altered in any way)

 

also put in a new coolant temp sensor(no corrosion on the connection at all)

 

Just took off the upper radiator hose that was pretty full looking.  Was able to add fluid, and I found that every time I would fill the hose to the top it would make a stream of fluid come out of the radiator where the upper hose was supposed to be.  I put the upper hose back on and filled the radiator until full from the cap. 

 

Went for a drive to get the engine up to normal temp and still the temp is riding at the C mark

 

Heater works great!

 

No bubbles in the overflow tank whatsoever=)

 

Drives like a new car

 

On my other 96 legacy with 259,000 I always just took the cap off, added fluid and was good to go?

Edited August 31, 201312 yr by Grasshopper2.2

Could be that your Temp Gauge isn't working right because the sender is bad.  It mounts in the crossover pipe right next to the ECTS.

 

Congrats on getting her running "like a new car!" 

Did you replace the 1 wire sensor or the 2 wire sensor?

Hmm, it had two wires in the clip that connects to the sensor.  I remember you saying its the "single wire", but that's the only sensor I could find in that area of the engine?

Edited August 31, 201312 yr by Grasshopper2.2

  Thank you,  I found that single wire sender for the gauge, I ordered one off ebay, and will throw that in there when I get it!

 

http://forums.nasioc.com/forums/showthread.php?t=1274787 I found this helpful

Edited August 31, 201312 yr by Grasshopper2.2

The two wire sensor feeds the ECU. Has no connection to the gauge.

 

The sensors should be right next to each other on the crossover pipe. I seem to remember having to remove one in order to get a wrench on the other one. It has been a while since I've had to change one though.

 

The gauge sensor is small, only has a 12mm hex drive, and a single spade sticking off the end of the sensor. There is no connector plug like on the 2 wire sensor. The female spade connector in the wire harness is just insulated with shrink tubing. More than likely, the spade terminal just needs to be cleaned up. Corrosion on the spade terminal increases the resistance of the connection, which means lower current flow through the sensor.

High resistance = cold temp. Low resistance = high temp.

If you were to remove the wire and ground it to the engine block the temp gauge would peg way over hot.

That makes sense.  I can't believe I didn't see that while I was in there putting in the ECTS lol.  I saw it, but was so focused on the ECTS that it didn't even register that it was the single wire spade connector you spoke of.  I pulled the wire off and there was no visible corrosion, looked clean as can be, so I just ordered a new one off ebay.  I'll post the results when I get the new sensor installed.

 

Can I ground the wire to the block to see if it makes the gauge shoot up, without damaging the gauge or anything?

this will be a first.

i don't think i have ever heard of a gauge temp sensor going bad.

Migh pull the sensor put and clean the threads. Sensor grounds through the crossover pipe, so it needs a semi-clean connection to work properly.

 

No harm done by grounding the sensor wire, though its more fun if you have a long jumper wire that you can ground in the car (under the dash somewhere) and watch the gauge flip out.

!! Problem Solved !!  My temp gauge is now working properly.  The sender for the gauge was no good.  I removed the original and it looked perfect, I cleaned it and put it back in, still no temp gauge.  Got a new coolant temp sender installed today, and finally my temp gauge is at a constant normal operating temp!  Almost the best thing that's happened to my car so far... couldn't have done it without you, much appreciated.