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Discussion Starter · #1 · (Edited)
I have been dealing with an overheating issue for the last couple of months that has been driving me up the wall. Originally the vehicle was leaking coolant from the radiator and possibly the water pump, we replaced both as well as the thermostat and the issue seemed fixed. Went for a test drive and every 2-3 miles we had to pull over to let the engine cool. Pulled out the thermostat and have been driving without for about a month now. From what I understand, without a thermostat the engine has a constant flow of coolant and won't run hot. Thing is, it heats up quickly whenever I'm pulling a grade or at highway speed and especially during a long trip.
Originally when we purchased the car, assuming it would be an easy enough fix, a mechanic claimed that there was a head gasket problem and that was the cause of the coolant leak. We dismissed this since the spark plugs were clean and the original radiator had a small hole in it.
Its been a few months now and just yesterday on a trip we started overheating again. Anyone have some idea on a possible cause? All the fluids are full, oil is clean, and I haven't detected any leaks whatsoever at this point.

Edit: 214K Mileage and it's a 4 cylinder.
 

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fans engaging as the engine heats, and spinning fast enough?

OEM thermostat and rad cap?
 

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Discussion Starter · #3 ·
The fans engage just fine, the radiator cap is new with the radiator. I had a new thermostat in it as well but it is overheating without a thermostat.
 

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4 cylinder, 6 cylinder ?

(or possibly if you are outside the US/Canada, ...a turbo 4?)

and miles on it?
 

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The fans engage just fine, the radiator cap is new with the radiator. I had a new thermostat in it as well but it is overheating without a thermostat.
the reason why I asked if the rad cap was OEM.

subaru caps measure and relieve in KPA,

and even on a new aftermarket radiator a little tighter or looser aftermarket cap will do odd things to the cooling system,...such as make it overheat for no known reason. (lots of cars pop up here with a new/ bad aftermarket cap).

the subaru cap # is 45137AE00B = $8.00 worth of piece of mind. (really cheap as it fits like all .."legacy/ outback" cars from 2000-2014).
 

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I was just thinking you could have air bubbles in the system also.

how many times did you burp? (putting the car facing up grade with the cold rad neck open without a cap, and a funnel or bottle on the neck to catch the burped bubbles)

...some cars need repeat burping. it is usually found out as people all of a sudden have no heat as the air bubble lands in the heater core, ...but if you are not using the heat you will not know.

after the rad swap did you pressurize the cooling system looking for leaks? (lots of hoses there now 13 or 14 years old,..and can start leaking or sucking air, or sucking closed one at a time).
 

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Discussion Starter · #8 ·
Thanks for the thoughts, I'll go ahead and try burping the system and seeing how many bubble I get. I will have to check on that cover you posted, can't say I remember off hand what I'm running with at present.
 

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Can you get to the radiator to feel if there are any cool spots? I had the same problem with a cool spot in the center of my radiator. I replaced everything but had something in the center of the radiator that clogged it. Changed it out again and all was fine. It is imperative you have OEM parts though my rad was after market. Also check your top and bottom hoses, they should be very hot so be careful, if they are not hot then there is a clog somewhere. Do you have a temp reading and time it takes to overheat? Make sure you have heat on high inside the cabin and nose up when you burp.

All the best!
 
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