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Discussion Starter · #1 ·
hi all, i just purchased a 2011 OB 2.5 and, it has 150K on the clock. wonderful running/driving car, i am liking it as compared to the 90's legacy's and the current 2 2001 OB's we already have. that said, the new addition has a problem, that i'm looking for input on......
the car overheats, after about an hour or so of varied driving. as in, the red temp light starts to blink, i stop and let it sit. anyway, there are no bubbles in the coolant, and no steaming out the exhaust. i pump/pressure-tested the coolant system (snap-on hand pump sealed on radiarir cap opening) it held 30psi for over an hour.
now, when she gets hot, it pushes coolant out of the overflow canister.
i removed the cap, placed my spill-proof funnel in top of radiator, start the car, and it fills the funnel half way up, and is boiling the coolant.....all this, while the lower radiator hose, coming from the water pump, is cold to the touch!!!!!. i replaced the thermostat, and burped the system with no change?
are the water pumps on these known for failing and NOT circulating the coolant? the hot, tight, pressured up upper hose and un-pressured, cool lower hose has me stumped. any input is appreciated........
 

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OBW H6 VDC, Tribeca, XT6
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are the water pumps on these known for failing and NOT circulating the coolant?
definitely not.

1. burp and properly refill the radiator. maybe the system had air in it when you bought it. they won't flow if there's air in the system.

2. headgaskets. that's classic intitial internal headgasket symptoms. they won't mix oil and coolant or fail a compression test. they blow exhaust gases into the coolant, that will be the first and only symptom until it gets worse.

look for bubbles in the overflow tank at various times, not just when it's overheating...at that point it might just be "boiling" and not actually bubbles. you're looking for bubbles, not boiling.
 

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Discussion Starter · #5 ·
i forgot to mention. the car never gets much heat at the venys or defrost, even when its getting hot. had my funnel in the radiator, trying for the third time, to burp the system, the heater on full blast, the car went from dead cold, till it finally started boiling coolant out of my funnel, and onlt then, just before it turned the red flashing temp light on, it finally made heat. all the blend-door and temp controls are working correctly. as are both fans are kicking on and working properly.
and, there have not been any bubbles present at any time in the radiator or the overflow canister, cold, warm, or hot.....
 

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OBW H6 VDC, Tribeca, XT6
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you really should quit running it into the red. that's bad on headgaskets and oil/rod bearings.

replace the thermostat if you never get any heat and no bubbles.

if you run the car *without overheating at all* for some considerable miles - does it use any coolant at all?

"just purchased" - dealer, any prior information or maintenance history at all?

HG leak after an hour or more of driving doesn’t sound right. Hg would cause this far sooner.
it's not common but they can internally consume small amounts of coolant, not noticeable at the tail pipe, until the level of coolant is too low and they overheat.
 

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Discussion Starter · #8 ·
as stated in the first post, already replaced thermostat, with no change. i already stated, "no coolant curculation", and no coolant loss except what gets pushed out of the overflow canister. again, looking for some help or direction.......
 

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found the culprit to be a very, very clogged up radiator. thanks everyone for the input.
how did you diagnose it?

Could be a misdiaganosis or additional symptom and not the root cause.

1. The heater core should provide cabin heat with a clogged radiator. the heater core supply and return is not from or to the radiator. supply is from the engine and return is to the water pump. the clogged radiator subaru's i've seen do have cabin heat. but i haven't seen many so that's anecdotal.

Maybe there's a way for the radiator to fail that prevents proper water pump circulation, like if it's completely blocked, but technically speaking you can completely remove the radiator and the heater core still has coolant supply and return independent of the radiator.

2. A clogged radiator, on an overheating car, which you just bought has quite a few red flags. if the radiator was indeed clogged then it might be a symptom of something else rather than a root cause.

3. or maybe it was a clogged radiator and clogged heater core - do you now have cabin heat?
 

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2008 Outback 2.5
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Very likely both a clogged radiator and heater core. They both run small passages for coolant and can get blocked easily with sludge or scale build up. A new radiator will solve the overheating problem but not the "no heat" problem and a restricted heater core will reduce the circulation of coolant through the engine. First try to flush out the heater core. A replacement heater core is cheap, but you have to disassemble the entire dash to get to it and it's a full day job yourself or upwards of $1k for a shop to do it.
 

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Discussion Starter · #16 ·
lets see. i replaced radiator, completely flushed coolant system, heater core, and block. car runs great. has hot heat, and no issues since...thanks again to all who responded.........
 

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lets see. i replaced radiator, completely flushed coolant system, heater core, and block. car runs great. has hot heat, and no issues since...thanks again to all who responded.........
I would continue to monitor your overflow level (I'd check with every fuel fill-up) for activity. Varying overflow levels, bubbles, etc, could still indicate an issue. Not to say a clogged rad was your only issue, but with the increased frequency of internal failures I see with HG in the 2010+ design and extremely few "clogged" radiators I've actually come across, I would be cautious.

For future reference to searching people, clogged radiators usually present as such in Subarus:

-Long, slow overheat (not rapid cycling of the temp gauge/light)
-Stays cool(er) at low speed/demand (overheats at high speed/high demand driving)
-Fans will not turn off at idle (and A/C, defrost off)
-Takes a long time to cool down while idling, but will cool down
-Plenty of cabin heat
-Raised overflow level, but no bubbling
-Hot upper hose, cool lower hose

The distinct difference with failed HGs are:

-Loss of cabin heat as engine temp increases
-Rapid temperature spikes, and cools almost instantly
-Overflow bottle spills over
-Bubbling of coolant in overflow
-Overflow level rises during overheat, does not return to normal after cooling down, and radiator is low on fluid
-Upper rad hose is hot and highly pressurized, lower is cold and stiff
-Black debris in overflow bottle
 

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lets see. i replaced radiator, completely flushed coolant system, heater core, and block. car runs great. has hot heat, and no issues since...thanks again to all who responded.........
I'm having this EXACT problem on my 2011 OB 2.5 that I just bought thru auction cheap...think the previous owner had issues and just ditched it... I'm going to try a flush first and see if that helps at all but I was thinking it was a plugged heater core but rad will be easier to change I think if needed..lol
 
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