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· Registered
12 Posts
Discussion Starter · #1 ·
Okay, I believe I have a blown head gasket in my 2002 WRX. It has 158k on it, which is probably fitting the mileage and age description of when they usually go bad.

I just recently seen how the car would overheat when idling, but when given gas, it would drop down in temp. Also, when idling, the car wouldn't blow hot air, but when driving, it would. So I replaced the thermostat with a Gates OEM style. Which was 100% identical with the stock one I removed.

Well, I flushed the coolant when I installed the new thermostat. I let the car suck in the coolant from the reservoir and slowly added new coolant in as needed. Also added the Subaru coolant conditioner. I never added anything to the overflow beside the radiator. (2002 don't have radiator caps).

Well, when the car finally accepted no more coolant (2 gallons went in + the conditioner) I have been taking it as my daily for the last few days. I have noticed that after hard pulls of boost, that my overflow (remember, empty) has completely filled up, and is BOILING out the cap. And when I idle, I also lose hot air. But when I drive, it warms up again. Almost as if I had low coolant or another sticking thermostat? If I drive it normal without hitting too much boost it won't overflow. The car has actually been running cooler than normal. The needle stays below the half way mark. It never rises. And the car never smokes. But I do lose antifreeze when it boils over. And when it boils over, I lose A LOT.

The overflow does bubble, has a steamy look to it after those hard runs. But I'm pretty sure I do smell exhaust in the overflow. I don't see any particles floating around, but my over tank is filthy with crusty dirt looking **** over the walls of the tank.

I'm 100% it's a blown head gasket. It's just weird it doesn't smoke or overheat. But I've learned that nothing is surprising with Subarus.

And I don't know anyone around that works on Subies locally to me. So, I guess I'm stuck doing it myself. And it looks as if I'm going to have to pull the engine just to get to them.

Best worst 3500 I've ever spent on a car lol

Coolant does get sucked back into the system and doesn't stay in the overflow. It always goes back to bone dry like it was previously. My bottom hose doesn't get hot, or feel like it has any pressure. Could it be a faulty thermostat? Or blockage in my radiator somewhere?

The bubbles and steamy overflow after hard boost still leads me to believe it's my head gasket.

· Super Moderator (Actually a SuperSpy)
30,450 Posts
Head gaskets do not usually fail.

You do not need to remove the engine to fix a head gasket but it's also not an unreasonable idea.

Pressure test the system. If it passes, burp it.
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