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Thermostat Question

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I'm in the process of swapping out an old radiator. I noticed the lower radiator hose drained free of coolant and stopped quickly. I assumed that this was due to the thermostat being located at bottom of block.


About 10 minutes later the lower house started draining again and stopped.


A few minutes later it gurgled and started slow leaking continuously. I plugged it with a juice container...


So my concern, does this mean my thermostat is not working and is normally blowing by some level of coolant? I could have swarm the thermostat stayed closed last winter when I installed upper and lower hoses.


Any thoughts? Nearest dealer is over 40 minutes each way. And I’d need to get there nthis morning (Saturday parts hours).

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the t-stat is located on the rad side of the water pump,

basically at the end of the lower hose.

with it closed, the coolant is going to flow out very slowly, if at all.

so do not worry.



do not replace the t-stat UNLESS you use a subaru part.

part store t-stat are not as good.



read up on how to re-fill the system.

failure to do it properly will result in overheating.

and overheating an ej25 engine can cause head gaskets to blow.

you have been warned.









why are you replacing the radiator?


good luck.

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I swapped over the 1” core from the early outbacks into a 95 Legacy, EJ22. No t-stat swap. I tried to reply sooner, but the interwebsnwas not happynwith my login.


Notes for the swap:


You need the fans from the outback as well. The smaller 5/8” core's fans have a different bolt setup/pattern. It appears the fans are the same, unbolt three bolts from shrouds. The shrouds are different. Electric connectors are the same, no re-wiring.


The radiator brackets are steel with bolts, most of mine snapped. Be ready with some good drill bits and a tap (believe they were m6x1)


Overflows were interchangeable.


You need the outback upper radiator brackets, different from the 5/8" core.


The bracket are just rubber grommets. I just had to swap mine into the other oem-pre-punched hole.


I use a combination of hand burping the system with the upper hose, and top off from the corner screw (opposite rad cap on radiator). Give it some time to settler on the first fill, give the engine a quick idle/cool down, then repeat. Has worked well so far. Usually takes three cycles to top off, then I'll check after a week, or a solid hour drive.

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