Updates (For others with similar situations) :

This problem is because of a head gasket failure & breach. Additionally due to the heads being slightly warped from overheating and or heat ups. I've changed radiator caps, burped the coolant system several times, and as time has gone on it seems to have only gotten worse. The car is pushing coolant into the expansion (Recovery Tank) and it also has bubbles in the coolant expansion tank.

I'd also like to point out the car passed several block tests. However the HG leak is so small that it really shows its issues while under boost (at first) and as time goes on it will happen under normal driving conditions and out of boost; However it was so small that the block test was always negative.

Regardless, bubbling in the coolant expansion is occurring when even at normal temps, or spiking, and or overheating. (Seems to be pretty constantly showing signs of bubbles)

If you see this on your car and you have checked the obvious things (fans, caps, coolant level, tstat, so forth), you might as well be starting to have a HG issue. Started very randomly and slowly and since only gotten worse.


Also in the picture of the example I have posted. The red line on the "uphill" (right side) represents where the needle would move to. (just putting that there to clear up any confusion)

My headgasket was bad and both heads were warped based on the specs from Subaru and what is tolerant. I had the heads machined and new gaskets put on. The car runs perfect and I no longer am seeing coolant pushing or bubbles.


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Coolant Temp Rising Uphill

I've had my share of overheating issues, mostly on long drives (4+ hours) then coming off the freeway and noticing the temp going way up. When this happened I would always notice the Coolant Overflow Reservoir filled up to the top.

I had an early 90K maintenance completed over a year ago and was told I had a lot of air in my coolant system. Rewind: About 2 years back I actually had a puncture in my upper radiator hose which damn near emptied the whole coolant system. I refilled the system but failed to "burp" it. Doh!

Anyhow, fast forward to today; I am driving back from Modesto to Oakland. I get to the Altamount Pass and begin climbing. Driving normally not pushing the car, and I notice my temp gauge starting to raise. It rose up a bit but it brought back some memories of the days I had air in the system. I ended up blasting the heater with the windows down but noticed as soon as load from the uphill climb was down with; aka going downhill, the temp went back to its normal position.

Everything was looking fine until I reached in between Pleasanton and Castro valley on 580. There is a slight incline, nothing like the Altamount Pass, but sure enough under load the temp shot back up to the same position. Likewise, going back to downhill normal driving; the temp when to its normal position.


Granted the temperature is not super high; then again I laid completely off the throttle as much as I could, but I am concerned about it shooting up since it never does.



Anyhow any thoughts/suggestions? The system has been fully changed and burped a while back. Never had an issue until today. Maybe I'm over reacting... i donnoo..


Check the attachment for an example of the slight temp raise, it stayed in the "norm" zone but makes me wonder how fast it would have climbed on prolong uphill driving.

Thanks in advance!

 

I should note upon arriving home I checked the coolant overflow, it was about an inch above the fill line. It also was bubbling every few seconds. I've seen this before so I'm not sure if that is norm or not.

 

probably still some air in system, similar thing happened to me - temp rises on hills (was while idling though)

had my coolant done shortly before, had it reburped and issue was solved

 

if it was bubbling, there was probably some air escaping...pockets of air can get caught in the hoses, squeeze some of the hoses while burping coolant and you can sometimes see extra bubbles come up

 

Thanks slugrx, I'll give that a try. I am hoping it is something small but you never know.

 

Hopefully it's not damage from previous overheating. Overheating is veryyyyyy bad. This is a shame, I've never had any issues with all my subarus. I've always been glad the stock system is so reliable. So it sounds like you got some bad luck, hope it doesn't steer you away from the cause.


I'd be curious what happens when you are driving up a hill and the gauge starts to rise if you just pull over and let the car idle, what happens then?

 

This happened to my gf camry, it was the thermostat. dont know if it would be the same issue tho, gl

 

I dont know but its something I could test out. I didn't even pull over since it was not climbing extremely high. The gauge would blip up as I was going uphill. it never climbed out of the middle mark or past the two main "normal" temp marks on the gauge.

But regaurdless of it not climbing high, it still climbed and it never does that unless it is about to overheat or get to that point.

 

That could be possible, I am highly doubting it though. I barely have ~86-87K miles on the car, but it maybe worth testing.

 

I'd have the cooling system pressure tested and or have the coolant tested for exhaust gases. Hopefully you dont have a blown head gasket, You never mentioned that you have had to add fluid so I guess you would be safe from the head gasket problem.

 

I did not think that half way up was hot or overheating lol

 

I agree with that but it is strange that this has not happened before while driving uphill. I'm being very caution and for good reason; hence the post.

 

Looking at your gauge shots, it doesn't look like the temps went up that much for a long uphill. That small a change is normal. If you have the AC on, that can also boost coolant temps because the condenser is dumping heat in the airstream ahead of the radiator.

If the thermostat was not opening, then it would have overheated long before you got to the Altamont pass. I just replaced a buddies thermostat in his Mazda and he couldn't even drive the few blocks to the freeway before it was spewing coolant.

A FMIC will also increase your coolant temps if you have one.

 

Well pulling over and leaving the car on if it was on the verge of overheating should infact make it overheat faster because there is no airflow going to the radiator. My subaru never changes its temp like this. My 04 wrx, 05 sti and 06 sti all have been very consistent temp even in very hot weather.

People you are saying oh thats not overheating, but keep in mind the car has had problem in the past, and has overheated and dumped all it's coolant. So if you don't think there is any issue, wise up! Shouldn't change that much. Could be a simple problem, but something isn't right.

Can you run AP and confirm the temp actually rising when it says?