I have a 1996 Subaru Outback with almost 200k. Yesterday, I drove about a mile and a half and noticed that the temperature guage was all the way up. No a/c on, just around town driving with air temp about 65f. I wanted to get home so I cranked the heat to try to dissipate the temperature of the engine. No heat came on. It just blew ambient air. Then when I got home, I noticed that there was coolant dripping slowing from the front passenger side. I think that there’s an overflow valve there for when the pressure builds in the radiator too much (that could be totally wrong). In any case, I added coolant this mornning and tried it out again. Same result. Any ideas?
I would suggest that you have the engine checked for a blown head gasket. This is a known issue on Outbacks of the '96-'02 vintage, once they have passed 100k.
In the short-term, a blown head gasket will cause the engine to run very hot, and possibly overheat. That can lead to swarped cylinder head, or other more serious types of engine damage. It can also lead to dilution of the motor oil with coolant, which will lead to bearing damage.
Most likely, the lack of heat from the heater was as a result of a low coolant level in the cooling system and heater. While the cause of all of these problems could be an external leak, such as from a broken hose–which can be serious enough in and of itself–it is also very possible that the low coolant level was as a result of internal consumption of coolant as a result of a bad head gasket (or two).
Incidentally, there is no overflow on modern cooling systems. That was replaced many years ago by overflow containers (yours is next to the battery, alongside the radiator), and if there is coolant leaking, you can definitely rule out the old-fashioned overflow that you may have had on earlier cars.
Get this situation checked out immediately, as one of the sure ways to ruin an engine is to drive it while it is overheating. With any luck, you stopped in time, but you should be prepared for a VERY large repair bill for replacement of both head gaskets.
It’s not the overflow, which is on the driver’s side. You have a coolant leak, and if you continue to drive the car you will very likely damage the engine (if you haven’t already).
How much coolant did you add this morning, and where did you add it?
From here it’s impossible to know what’s leaking, but you must either figure it out and fix it yourself or get the car to a mechanic ASAP.
Subarus do not take kindly to overheating. Don’t fool around with this.