Coolant coming out of overflow

So my son inherited the Legacy. It's pushing coolant out the over flow every once in a while. We recently added a new stereo that has gauges.

 

 

He noticed the temp hit 250 and the AC wasn't blowing cold at the same time.

 

 

I'm thinking fans. Whats, the best way to test relays vs. fans as the issue?

 

 

Thanks

Pushing coolant out of the overflow means that gas is entering the coolant system.

 

 

On Subaru boxer engines, this is caused by a headgasket leak, combustion gases enter the coolant around the cylinders and that causes bubbles in the overflow bottle and when it's really bad it pushes coolant into that bottle.

 

 

Because there is now gas taking up the space that the coolant once did in your system, the coolant does not get drawn back into the system from the overflow bottle.

 

 

Anyway, time to test for a blown headgasket.

I suspect the ECU will cut off the AC if the car is overheating.

 

When the car is cooled down, check the radiator to make sure it’s full. If it’s got a big air pocket it’s likely the head gaskets. On mine I tried a new radiator cap hoping the original was bad and stopping the overflow from drawing back into the radiator but it didn’t help, I needed new head gaskets.

 

I’d get a dealer to diagnose it and then open a case with SOA requesting goodwill help. Unless you plan on just trading it in as is.

As for the fans, it’s hot enough this week that you could see if they’re working by just letting the car idle.

 

If you really delve into them, check out this guy for troubleshooting tips:

 

Edited July 17, 2019 by NVAKeith

So my son inherited the Legacy. It's pushing coolant out the over flow every once in a while. We recently added a new stereo that has gauges.

 

 

He noticed the temp hit 250 and the AC wasn't blowing cold at the same time.

 

 

I'm thinking fans. Whats, the best way to test relays vs. fans as the issue?

 

 

Thanks

 

Kind of sounds like something to do with the engine internals, like the head gaskets or something...

the very first thing I would do is replace your radiator cap...

the very first thing I would do is replace your radiator cap...

 

+1, shouldn't be too expensive either.

Pushing coolant out of the overflow means that gas is entering the coolant system.

 

 

On Subaru boxer engines, this is caused by a headgasket leak, combustion gases enter the coolant around the cylinders and that causes bubbles in the overflow bottle and when it's really bad it pushes coolant into that bottle.

 

 

Because there is now gas taking up the space that the coolant once did in your system, the coolant does not get drawn back into the system from the overflow bottle.

 

 

Anyway, time to test for a blown headgasket.

 

 

or it means your radiator cap is not holding pressure. common occurrence as the caps get old and weaker from the constant heat cold cycling and the rubber seals break down

or it means your radiator cap is not holding pressure. common occurrence as the caps get old and weaker from the constant heat cold cycling and the rubber seals break down

 

 

 

I agree that it’s worth a shot. I think I speak for everybody when I say we’d all be happier if it was just a radiator cap failure.

 

It does sound like classic head gasket failure between the combustion chamber and a coolant passage forcing combustion gasses into the cooling system. That would be sucky.

 

 

Sent from my iPhone using Tapatalk

^

don't guess then, get a coolant tester like this one

 

 

https://smile.amazon.com/Block-Tester-BT-500-Combustion-Leak/dp/B06VVBSFTF/ref=sr_1_8?crid=VH5LGGKVW1DK&keywords=coolant+tester&qid=1563466955&s=automotive&sprefix=coolant+tester%2Caps%2C173&sr=1-8

 

 

when the rad cap fails, it will blow coolant out of the over flow tank just like a blown head gasket will due to the systems inability to pressurize...

I agree that testing the system is the only way to find out.

 

It would be interesting to see a comparison of blown head gaskets to failed radiator caps in Subaru's.

^

don't guess then, get a coolant tester like this one

 

 

https://smile.amazon.com/Block-Tester-BT-500-Combustion-Leak/dp/B06VVBSFTF/ref=sr_1_8?crid=VH5LGGKVW1DK&keywords=coolant+tester&qid=1563466955&s=automotive&sprefix=coolant+tester%2Caps%2C173&sr=1-8

 

 

when the rad cap fails, it will blow coolant out of the over flow tank just like a blown head gasket will due to the systems inability to pressurize...

 

Sounds like a great idea, and not breaking you're wallet either

You can rent these from auto zone. I used it on my STi, I passed according to this test but I’m still leaning towards head gaskets for myself. I have the same problem. She eats coolant and it sometimes pushes coolant out the overflow. No leaks, no bubbles in the overflow tank, no white smoke, no other normal head gasket signs. But coolant is going somewhere and it’s not the leaking*. System holds pressure too

I recently had this same problem. I bought a new radiator cap and that tester linked above. Fortunately I not have a leak. However, I still added the OEM coolant conditioner and topped off the coolant. I'll be keeping an eye on the cooling system over the next few weeks.

 

 

 

https://www.amazon.com/Subaru-OEM-Coolant-System-Conditioner/dp/B00WFI0W2Q/ref=sr_1_fkmrnull_4?crid=1OLNYD15MKLME&keywords=subaru+coolant+additive&qid=1552941173&s=gateway&sprefix=subaru+coolant+additive%2Caps%2C238&sr=8-4-fkmrnull