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Old 07-16-2013, 12:01 PM   #1
Scooby Newbie
Member#: 347756
Join Date: Feb 2013
Chapter/Region: VIC
Location: Coquitlam, BC
2005 Outback XT

Default Overheating OBXT, top rad hose hot, bottom cold.

Hey guys! My Outback suddenly started gaining heat incredibly fast. I noticed it yesterday, topped up the coolant, drove it to work today and had to turn on the heaters full blast to keep it cool.

I'll log it later today to check the AFR and make sure I'm not running lean (stage one open source tune), but I logged extensively after the tune and I was running a little rich the whole time.

I grabbed the top hose and it was hot, the bottom hose was lukewarm.

The water pump and thermostat were replaced at the beginning of May this year, with Gates parts

Any ideas would be greatly appreciated!
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Old 07-16-2013, 04:09 PM   #2
Scooby Newbie
Member#: 281522
Join Date: Apr 2011
Chapter/Region: Tri-State
Location: Albany Ny
05 Outback 2.5XT


recheck the thermostat. it's not working from your description. did you redrill the hole to 1/8 in it?
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Old 07-16-2013, 06:26 PM   #3
Sammo Hung
Member#: 10613
Join Date: Sep 2001
Chapter/Region: South East
Location: S Ga / N Fla


check coolant flow.
remove radiator cap and watch for fluid movement.
no movement..bad pump..

but from what you described about the hoses i would lean toward
a bad thermostat.
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Old 07-17-2013, 02:50 PM   #4
Scooby Specialist
Member#: 136296
Join Date: Dec 2006
Chapter/Region: TXIC
Location: Midtown, Houston, TX
2005 STi


Coolant flows from top-down in the radiator so the upper hose will be hot and the lower one should be colder but not cold.

Make sure you installed the thermostat properly. There's a relief hole drilled in the housing, it has to be pointed a certain way.

To check for coolant flow, you can take off the radiator cap (carefully, especially if the engine is "hot") and look for coolant swirling and flowing.

Here's a quick check for the water pump. Get the engine warm. Open the windows. Turn fans to max, no A/C, hottest setting. Let the engine idle. Does the air come out hot for a few minutes, or does it come out hot for a few seconds and then cool down?

If it stays hot for a few minutes, your pump and thermostat are probably fine. If it's hot for a few seconds and then cools down without you messing with the controls, your pump or your thermostat could be shot. Take the thermostat out and boil it in a pot of water. See if it opens up when in the hot boiling water. The stock thermostat is set for 180F so it should open up well before the water boils at 212.
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