2006 legacy wagon 2.5i coolant temp is cold

[Andremor]

Hey there everyone I've been having problems with my recently purchased 2006 subaru legacy wagon 2.5i. I've been reading some threads and haven't really seen anybody experiencing a similar problem. Now that we're in the end of November and the weather is colder my coolant temp gauge isn't rising past the first hash mark after the c. I drive on the highway everyday to work and I've found when the gauge does get halfway to the middle, once I get on the highway and do about 100kmh the gauge will dip down closer to the c. I do get a little heat coming from the vents but I've noticed my fuel milage is worse. My mechanic has tried flushing the heater core, checking the thermostat and changing the coolant temp sensor but I still have the problem. If anyone has any experience with this problem or have any ideas before I start spending big money on a new rad or new heater core it would be much appreciated

[bomberlegacy]

"Check" the the thermostat? Sounds like it's bad and needs to be replaced with an oem part

[DonnyJagaru]

I would agree with the above. Unfortunately to check the thermostat will call for a coolant purge but you can re-use the coolant if it doesn't get dirty. Just filter it through a coffee filter to remove any grit.

 

I would also check the ODBII and see what temp it is reporting. It should be very close to the Thermostat rating and creep up a little at idle before the electric fans come on.

[Andremor]

Thanks for the quick responses guys, sorry I couldn't update sooner but I changed the thermostat and still having the problem. I've been trying to read as much as I possibly can on what the issue is and I'm thinking it might be the water pump. On cold days when I start the car I hear not so much of a grinding but a whirling type noise. The car is still not heating up to a normal temp, unless I am in traffic then it will make it to the halfway mark. If I'm driving faster the temp gauge will drop to around the first hash mark past the C. In the summer I do think use my a/c a lot but on a very hot day I had the A/C running and while I was in gridlock traffic I noticed it stop blowing cold. When I looked at the temp gauge it was rising so I turned the heat on all the way and it dropped back down to normal. At the time I thought maybe because it was a hot day that happened but now that I'm having it running too cold in the winter I think it may be related. I'm no mechanic so I'm just speculating but from what I've read the water pump sounds like it could be the culprit. I talked to my mechanic and he said it's possible that the guy I bought the car from put on an aftermarket water pump and it's starting to fail already. I'm just worried about the coolant temp dropping too low and somehow damaging my engine. I honestly don't know if running too cold will damage anything but if someone could enlighten me on that I would much appreciate it. I've been too worried about it to go see my family as they live about 2 hours away and with Xmas coming up Imy gonna have to chance it if I can't get it fixed. One other thing I forgot to mention was the check engine light is on (and it's very annoying with the cruise control light flashing as well). It's been on since I've had the problem I forgot to mention it in the original post. I read the codes and one was for my o2 sensor and another was coolant temp was too low. Sorry I don't remember the code numbers or what they said exactly but I'm going to use my friends reader tomorrow and update with proper codes and descriptions. Sorry for rambling on but if anyone could help me with figuring this out or confirming my suspicions of the water pump I would really appreciate it.

 

Thanks again

Andre

[NORULZleggy]

I have a Gates pump, and OEM subie thermostat, works great. With My Amsoil coolant and coolant boost I run cooler then normal when driving hard but normal when in traffic. I would get a gates water pump, and change coolant while your at it. I did this all my self and all worked great. GL

[GEE-OTTO]

I would pick up a new water pump and coolant temp sensor, then have your mechanic inspect the existing pump.

 

The impeller is direct drive so its always turning, the seals and bearings fail but that usually results in external leakage. When my gates pump failed the impeller was actually not spinning at the same speed as the input shaft, like it was loosely pressed on to the shaft.

 

The A/C and the heat issues are odd b/c the AC is a separate sealed system if it stops blowing cold that means its lost its drive (slipping belt or a bad clutch) if the heat blows cold you have a clogged heater core.

 

When you bought this car was there ever any records of headgasket repair or work? It could be as simple as a bad temp sensor or failing water pump to as complicated as a clogged radiator and or heater core.

[SubOperator]

I can't imagine a working engine not warming up to a operating temperature. Your sensor readings may be wrong if the sensor is bad. Unless you have some monster radiator your engine temperature MUST be at some point around middle of the scale.

 

You need to get systematic with symptoms, sorry your description is rather chaotic which does not help. So go step by step, something like this:

 

1. On cold engine, open the radiator cap and see if you actually have coolant in the radiator.

2. Before and after driving, notice coolant level in the expansion tank, it should get higher after a drive, and then get back to "cold" level after you let the engine cool.

3. After engine runs for few minutes the heater should start blowing warm air and in short time after that it should get hot.

4. Try to notice if you ever have your radiator fans turn on if you let the car sit idling or you are sitting in the traffic.

 

Cooling system is not really complicated. And I agree with GEE-OTTO that your AC issues are most likely unrelated to your engine temperature issues.

[RustyRuu]

nothing has been asked about the temperatures where this guy lives. this happened to me the last couple days we've been in the high 12 degrees F. Canada has been so kind as to give Colorado its arctic storms. i've been bottoming out from snow build up even because the stock legacy is that low, i wish i could afford a tranny for my outback right now, but back to what i was saying.

 

so i can get up to operating temperature in town very easy. you began to drive 55- 75+mph(sorry cant convert to KPH off the top of my head) that sucker gets cold. and you do to you have some heat-ish (at least warmer than out side). it was -2 today completely frozen road no actual asphalt for hours (i drove 4 continuous hours). i only got to operating temperature maybe 3 times. when it sat warming up and doing 3rd/4th gear high rpm pulls for multiple miles up long hills we call them passes here. but mostly i was sitting in the lower hash marks by the C on the gauge. this is not the first time and probably not the last. My gf's 09 forester has no gauge for how cold or hot you are running just a blue thermometer for when its a cold motor and a red one for when its too late and you already overheated it. but the blue one as come back on indicating a cold motor driving in the cold temperatures a couple times too, so thats just my cars and experiences and it seems to be normal for these N/A 2.5s.

 

so i began to think how to fix this problem... and i know someone here could do it better than me.

there are heaters that heat your coolant at night or just not operating it. what if you had one for when its completely frigid or going through huge fog patches that are -20F and begin to freeze your window, and are doing the same to your radiator. you could hook it up to your battery instead and have a switch or could possibly make it automatic to turn on and off depending on coolant temp.

this would be nice for us cold weather folk that like to still get out and do things in the coldest of weather. you ever hear a car cold start in -20? i hope i never have to again but know i will.

[GEE-OTTO]

I think you are overthinking this there really are two causes to this problem:

 

1. Bad temp sensor

2. A blockage

 

 

You get heat and it goes away while driving due to heat soak. If you idle your car for 20 mins and the fans never come one that is a sign of a bad temp sensor or fan relay.

 

While idling and up to temp (needle in the middle of the range) run the heat. If at first is really hot and starts to fade off you have a blockage somewhere.

 

Also while idling at at temp feel the lower radiator pipe it should be warm but not super hot, indicating coolant flow same for the top hose. The top should be cool until warmed up

then it too should be warm, if either hose is scalding hot something is blocked.

[NORULZleggy]

I think you are overthinking this there really are two causes to this problem:

 

 

GEE is right, It was -2 this morning, I started my car in the garage and let it idle for 5 mins. When I left for work and made it up my street driving 25 MPH, the car was warm. on the highway I assume the wind hitting the car doing 75 would be like -25 and my car temp was fine. Something is bad on the car.

[RustyRuu]

Not to steal OP thread, but thanks guys. I just rebuilt my bottom end (I'm at about 1000 miles). Now I have the top end problems to deal with that I forgot about when I took it off the road.

 

Could that temperature sensor throw a idle control malfunction CEL? One of my current struggles since the engine was put back in the car, another one would be my dead battery the last couple days but that's just bad luck.

[GEE-OTTO]

IACV could be malfunctioning or clogged you can replace it or clean it.

[RustyRuu]

It's been cleaned several times, and is too much for someone like me to drop all at once for a new one and wreckers are slacking on getting back to me and I'm slacking on going to a u_ pull_it. Guess we'll have to wait to find out. Gonna have to try and use a 96 obw battery for now since its sitting around.

 

How much coolant do you lose replacing the temperature sensor?

[GEE-OTTO]

It's been cleaned several times, and is too much for someone like me to drop all at once for a new one and wreckers are slacking on getting back to me and I'm slacking on going to a u_ pull_it. Guess we'll have to wait to find out. Gonna have to try and use a 96 obw battery for now since its sitting around.

 

How much coolant do you lose replacing the temperature sensor?

 

none

[RustyRuu]

I think you are overthinking this there really are two causes to this problem:

 

1. Bad temp sensor

2. A blockage

 

 

 

 

Also while idling at at temp feel the lower radiator pipe it should be warm but not super hot, indicating coolant flow same for the top hose. The top should be cool until warmed up

then it too should be warm, if either hose is scalding hot something is blocked.

 

i think this is my issue my lower hose is cold every time i drive and i've checked it after an hour of driving and 3 hours of driving its still cold.

 

gonna try and replace the thermostat and get back to you guys

[GEE-OTTO]

Yeah sounds like your Thermo is stuck closed and doesnt have a bypass hole. Go with the OEM t-stat it has a larger opening and is built better.