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Discussion Starter #1
hey guys, my 98 legacy gt 2.5 bru (auto trans) is overheating and has been in the shop for over 2 months and they cant figure out why, i have also done the following... oh and the engine only has about 85k on it.

-replaced stat and ended up removing completely
-checked the HG and for signs of HG issues (none)
-check the water pump, replaced timing belt while i was at it
-replaced the rad
-pressure tested entire cooling system and flushed
-bypassed the heater core
-bled and tried to readd coolant 50x + hooked a external pump to a bucket of antifreeze to force it through the system with the rad vent out just to make sure.

i can run the car in park at 3000rpm for 1 hour+ and no issues as soon as i put it into drive, not even 3 min it will overheat, i do not loose coolant unless its overheating and blowing out of the reservoir, while it overheats the top hose to the rad is burning hot, while the bottom to the engine is ice cold (both are nice and hot while its not overheating) ( even with out a stat) i also loose heat when it over heats (yes everything is bled 100%) PS could it be the tranny? should i try to loop the tranny to an external cooler? because it will only overheat in gear.

but my question today is.. if i get a japan 98 ej25 will my current computer work with it? i know i have to drill out the EGR which is no big issue i just do not want to get into computer and rewiring. Or could anyone suggest another engine that will bolt in + work with my tranny (not looking for more power just a working car.)


PS, iam a marine mechanic so ive been working on the car in my shop(but did have it at a auto mechanic shop for 2 months) and will be allday today aswell if anyone can think of other things to try iam going to loop the tranny and see what happens (maybe the tranny is heating up and causing my coolant to get to hot? i dont know iam pretty much at a wall. but ive done ALOT of tests and do not believe its the HG.
 

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Discussion Starter #3
What did you do to check for signs of HG issues?
its not foaming its not bubbling, iam not losing coolant its not burning coolant, i used the fluid dye and it never changed color 4x trying, also used the coolant tester and theres no exhaust atoms in it,

ps i just finnished looping the tranny and took her on a 2 hour drive never overheated untill i got back to my shop and put her in park, entire time driving heat was coming on and off :/ and when i pulled into the shop(still outside) heat went off and never came back on and she overheated.
 

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2001 VDC/SC One of a Kind
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An engine without a thermostat will run hot. It's called heat soak. The thermostat not only allows the coolant to exit the engine to cool, but it also restricts flow through the radiator to help cool.

Did you use a Subaru thermostat or a cheapy from the parts store?

Are the fans coming on? With AC or when it reaches hot? If they are on with the AC but not when hot, replace the two wire temp sensor. That's the one for the computer.
 

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Discussion Starter #5
An engine without a thermostat will run hot. It's called heat soak. The thermostat not only allows the coolant to exit the engine to cool, but it also restricts flow through the radiator to help cool.

Did you use a Subaru thermostat or a cheapy from the parts store?

Are the fans coming on? With AC or when it reaches hot? If they are on with the AC but not when hot, replace the two wire temp sensor. That's the one for the computer.
i got the stat from napa parts, yes the fans come on with AC and also stay on while hot, my original stat works fine while boiling it (subaru one) and still overheats, the napa one still overheated the car, and removing it completely still overheats just takes longer ofcourse
 

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'11 outback 2.5i premium '12 impreza sport limited
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probably will have to rewire everything in the car. you can probably get much better info on japanese engine swaps from another site like nasioc. the JDM drivetrains are usually very cheap in comparison to the stuff from another market.
 

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Are you sure about the water pump? As for the HG, how did you check it?

The absence of heat from the heater when the temp gauge is high interesting. When the HG fails internally, those are typical signs. But loss of heat from the heater could also be due to lack of coolant flow through the heater core. As the heater is in a constant flow circuit, setting aside air or exhaust gas pockets, this could be due to lack of flow, and that could explain the temperature gauge going up, and the cold return hose at the radiator.

There have been cases of the pump impeller corroding and in one photo I recall, the vanes were collapsed due to the resulting weakness. In another instance, the impeller was slipping on the shaft.

If the pump isn't working effectively to move coolant, there could be boiling around the cylinder walls; that could account for the blowing out the reservoir in the first post.

Just some thoughts . . . .
 

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2007 OBXT Limited, 5MT 148K
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I've also seen a radiator hose delaminate and actually pinch itself shut internally. It looked pretty normal outside.

It sounds like flow to me too.
 

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Have you hooked up a pressure testing gage to the Rad and ran the car?

This test will show if the head gasket it leaking pressure into the cooling system while not allowing water in to the engine.
 

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2001 VDC/SC One of a Kind
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DITO what Plain said.

JDM engines swap right in. Same harness. You'll have to put your AC compressor on because the plugs are different. And you'll need to extend the vacuum hose to the opposite side if the motor for the brake booster. Otherwise, no problem.
 

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Discussion Starter #11
well nothing ive tried worked sofar, it prolly is a HG issue, top rad hose was sucked right in this morning (first time this happened) pulling out engine and checking HG on wed.
 

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Discussion Starter #13
ok well i replaced the water pump timing belt again, the pullies because some were seizing by the feel of them uhmm PS the headgasket was GONE on one side and starting on other even tho i was 90% sure it wasnt that... so cheers to everyone and if you have these issues go for the HG.
 
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