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Ok folks, I'm hoping someone out there can help guide me to my problem area. I have a 2001 outback wagon with the 2.5L. It runs greats, but recently is have been pushing the antifreeze into the overflow and not drawing it back into the system. I did the obvious and changed out the radiator cap for a new one. That was not the problem. I put the car up in the air and pulled the cover off to have a look at the head gaskets. They were dry. I squeezed the lower radiator hose and had antifreeze come out of the thermostat housing. I figured the gasket went bad and replaced it. That seemed to work for a bit, but on my way back from a 300+ mile trip the car began having the same symptoms again. I stopped, shut the car off and burped they system until I was able to open the cap. The overflow was full but the radiator was again low on fluid. I topped it off and made it home with no trouble. My thoughts are it's the waterpump, but I had already replaced that no more than 8 months ago when the timing belt was done. I am hoping it's not the head gasket, but I am not sure. Wondering if anyone else out there had a similar problem and could tell me what they had done to fix it. Thanks for taking the time to read/reply folks! 

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Head gaskets for sure, IMO. I had a 99 with the same elusive issue, intermittent, and could not duplicate it in a radiator shop under continuous load. But it would happen driving 20 miles up a canyon or under continuous freeway driving. 

Maddening! My understanding is that exhaust gases were leaking internally into the coolant, superheating and pushing out the overflow. So I made the 20 minute drive up the canyon every morning, watching temp slowly rise at the end of the drive. And every night I would empty the overflow back into the radiator and drive home with no problem. I did not want to invest in that 200K car so finally sold it cheaply with full disclosure, which the previous seller had NOT done with me. Bad car karma. Good luck!

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coolant into the over flow bottle is normal, as you know.

but not sucking it back into the rad is a problem, again as you know.

this is just a guess, but i suspect the pressure forcing the coolant out to the overflow,

is greater than the suction drawing it back in.


the most common cause for this is a leak in the system.

the leak could be the cap, done,

the hose that runs to the overflow bottle,

any other hose in the system,

or it could be that the over flow bottle hose is jammed down in to the bottle too far,

preventing the suction from drawing it back into the rad.


i had a leak on my lower rad hose at the clamp once.

it only leaked when at full operating temp.

when cold at idle, nothing,

drive it on the hiway and then let it idle,

drip, drip, drip .


if the system leaks it will eventually cause an over heat situation.

this will force more coolant in to the overflow.

but when the system cools it may suck air at the leak point

instead of sucking coolant from the over flow bottle.


so look for leaks.

let the car idle in the drive way after driving around, and look for leaks.


it could also be caused by an internal head gasket leak,

exhaust gases leaking into the coolant.

this is very unusual for a 00 - 04 ej25 engine.

so i would look for another cause before focusing on head gaskets.

Edited by johnceggleston

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That type of head gasket failure is unusual for that engine.

I agree with John, I would look closely for leaks first. A leak up high in the system may not allow much coolant out during normal operation, but could easily let air in while the system is cooling.

A cooling system pressure test may pinpoint the source.


A leakdown test would confirm the head gasket theory.

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