Coolant issue

[Thesubielover]

At idle my car is over heating. When I drive the car or have it at idle with the cab air on there's no issue, but at idle with my cab air totally turned off the fans don't turn off or will go through one cycle of turning off then click back on again and while sitting at idle, the temp gauge slowly rises. When I'm driving though, with can air off there are no issues. Any thoughts? No CEL, not sure when the water pump was last replaced along with temp sensor or coolant sensor.

[Thesubielover]

Might I add that when it got hot last time a few days ago like this, I took off the coolant cap off and a geyser of bubble came from the tank. However I tried to burp the air out of the system today for about 20 minutes, with no changes.

[vrg3]

It's hard to say for sure what the cause is.

Turning on the air conditioning (assuming that's what you mean by "cab air") is masking the problem by bumping engine speed up a little. The alternator spins faster so it provides more juice to the radiator fans, which then spin faster. Also, the water pump turns faster.

Likewise, driving the car masks the problem by doing the above but also providing more airflow over the radiator.

Can you clarify what you mean by a "geyser of bubble?" Even a properly working cooling system will shoot a bunch of coolant out if you take the radiator cap off when it's hot.

If you have the means to run my scantool -- http://surrealmirage.com/vrg3/b10scan/ -- then you can do some checking on the temperature sensor, but the fact that the fans do turn on probably means the sensor is not the issue. More likely it's the thermostat or water pump.

In my mind the water pump is more likely just because of how the problem goes away when the car starts to move. How long have you had the car? If I were you I'd look at replacing the water pump anyway if it's of unknown age.

There's also always the chance that there's a head gasket leak, but let's hope that's not it. Tell us more about the bubbles. With the system closed do you see bubbles keep appearing in the overflow tank?

[Thesubielover]

So the A/C doesn't even have to be on. I guess I haven't looked in the over flow tank. When I burp the system it's with the tho' coolant tank casio off which I watch the coolant rise. Sometimes I notice a tiny pool of coolant on top of the aluminum coolant tank. Maybe my casio is also part of the issue and the way I'm burping the system. When I replaced the casio before with the car over heating the problem went away sure awhile. I will say I'm the second owner of this car with 120k original miles. I don't think it's the has gasket, I've had a couple inspections done and that never came up. If it is though then I'll have a great excuse for my dohc swap . Maybe I'll try burping the system with the coolant tank cap on and add more coolant to let the coolant.cycle through more.

[kimokalihi]

What is a casio?

[vrg3]

I feel like you could make your posts a lot clearer for us with just a little bit of effort. We'd be able to help you more if you did.

So, yeah, what's casio? And what's tho'? And what's cab air?

And what do you mean by "So the A/C doesn't even have to be on?"

You have some kind of aftermarket aluminum coolant tank? Tell us more about that.

Assuming it's an equivalent to the stock black plastic piece, coolant on there means a leaking radiator cap or a failing tank.

You'd have to have pretty bad air pockets or a pretty bad leak to cause it to overheat at idle though. Unless your tank is in a weird place, that's probably not it. And you'd still need to figure out the root cause of the air pockets to begin with.

Most people replace the water pump every 60,000 to 100,000 miles. I'm still putting my money there, based on my current understanding of what's happening with your car.

[kimokalihi]

He's got an ej20g metal tank located near the battery.

[kimokalihi]

Did you replace the coolant tank cap with a stock oem sti cap?

[Thesubielover]

What is a casio?

So casio, was supposed to be cap. I was using the oem cap that came with the tank, but I was having issues with it so I put on my original stock one and the symptoms went away. I'll be ordering a water pump, thermostat and wrx/sti coolant cap through subaru this week. Or ill just stop by on the way down or back home from kimo's. Thanks guys on your input

[kimokalihi]

Its gonna be considerably more expensive at the dealer for the pump and really any part and they won't have the turbo water pump in stock most likely.

[Thesubielover]

Oh yeah, ill order from that site you mentioned.

[kimokalihi]

Fur sure. I've spent thousands there probably. Great place to buy parts from. Almost always lower than all the other online subaru oem parts places and its in renton so shipping is quick.

[Thesubielover]

Niiice!

[rallyak]

I just replaced a radiator an condensor for the same issue. It wasn't able to cool because of to much debre in th cooling fins. Is this possible?

[91Beater]

When the A/C is turned on fan is forced-on on low with no regard to coolant temperature. The purpose is to cool the condenser so refrigerant can liquefy.

When A/C is enabled from the cab, it activates two relays. Fan relay and A/C relay. On Legacy first gen, when refrigerant pressure exceeds a threshold level it will push the fan over to high speed. If refrigerant pressure exceeds further due to blocked air flow or faulty fans the pressure relief on back of the compressor dumps the refrigerant into air to prevent component rupture.

When you disconnect power to compressor, IACV boost is disabled because ECM looks at this signal. The fan on is commanded at the A/C switch level, so fans will still come on without IACV activation.

So, if you disconnect the A/C compressor you can use the A/C switch to manually override the fans on without having the compressor coming on.

Replacing the condenser due to debris in outside fins is ridiculous. Condenser shouldn't be replaced unless it's leaking refrigerant or there's an obstruction inside the tube(s).

[rallyak]

the debris was like concrete and almost no air flow even after pressure washing it. Mind you this car also has over 700,000 miles of rocks and bugs cramed in it.
It not ridiculous its a valid question.

[kimokalihi]

700,000 miles??

[rallyak]

Yes 700,000 miles.

[kimokalihi]

WAY more than I've ever driven in my entire life! lol

[Legacy777]

That debris is pretty bad!!

[Thesubielover]

I think its the oem thermostat.