I have a2001 outback...My wifewasdriving this morning and the car ran hot...Sheput the heat on high audit cameo normal temps...When she got home and after it cooled down, I opened the. Cap on the radiator and it was full but the over flow was empty...Would the empty over flow cause that to happen???? Please help!!! It's our only transportation ...

No. But your radiator was low on fluid for some reason. When it cooled down, it sucked the fluid from the reserve jug. That's why your reserve jug was empty. Refill reserve jug and keep and eye on it. Pull your oil dipstick and make sure the oil isn't all milky. The fluid went someplace. If you notice it getting hot again, you may want to replace your thermostat. Keep an eye on your exhaust also. If you notice that it's very white and thick, that means you're burning coolant. If your burning coolant or you have milky oil, that means your head gasket is shot.

^^ditto. You could also look underneath the engine to see if you are leaking coolant, causing an air bubble inside the cooling system, from one of the cylinder heads, water pump, oil cooler (automatic) hoses, etc.

If anything it has to be leaking from somewhere....Had the heads replaced last year with new water pump, timing belt/chain....But with this weather being 2 degrees maybe I have a cracked hose or a hole in my radiator??? It's so hard to notice any leaks when we have a foot of snow on the ground...I'm gonna place a piece of cardboard under my car and fill the over flow then let it run....Maybe, just maybe the water is defective and it ent bad????

If you actually have water in the system, then yes, something probably cracked and broke. You should be running a 50/50 mix of water and anti- freeze. If you were running anti-freeze and water, you may want to buy a cheap tester and sample what's in your radiator. The tester should tell you the freeze temp of your mixture.

I am using a 50/50 prestone antifreeze....Someone said maybe the therosate is sticking causing the over flow to boil over???? Is that a possibility????

If it's the original thermostat, yes, there's a good chance that it's going bad. Sometimes the radiator cap itself goes bad and the coolant leaks from under the cap. Did you narrow down the leak yet?

Not seeing any leak....I will try running the car for a good 20 mins then see it any changes

I'm sure it's not the original thermostat, the car's almost 15 years old. Possible, but unlikely. Is it the original? How many miles are on your car?

I started the car today, filled the over flow back up, topped off radiator, let it run parked for about 1 hour with the heat off...I wanted to see if when the engine gets hot that the fan kicks on ( and it did )....So then I took it for a long ride and the car never ran hot! We are changing the therosate tomorrow or at least taken it out and checking it to see if it opens and closes....Lets see what happens......The only other thing I could like is there was a block of ice under the front bumper and maybe, just maybe it stopped the fan from turning until it melted.....

you could also try some of the dye stuff you can put in the radiator with a black light and see if there is a leak it is a a great way to spot a leak

Isn't there a way to check the radiator feeling it to see if it hot or cold?????

So far I did everything I thought was the right thing to do....The only other thing I can do is have a mechanic check the pressure in my radiator....I'm a women and I think I pretty much covered everything but that! If I put dye in the radiator it's not as good as doing the pressure check itself....Plus I am changing out the therosate either way....whether it's good or bad

Just change the thermostat and call it good. If the car doesn't over heat again, I wouldn't bother spending money on a pressure test. If you ran it for 20 minutes and you found no leaks, I would stop there. If you bring it in for a pressure test, you may get scammed into spending a ton of money on something you don't need.

I imagine that someone who has knowledge told you your thermostat needed replacement. If so, do that first and see if this remedies your problem. If not, get another opinion from an independent garage, find a reference if you can. A good diagnosis is money well spent before making unnecessary repairs.