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Weird coolant leakage - Subaru Legacy

Hello everyone,

A few days ago, the temp gauge in my 1995 Subaru Legacy went sky high in a matter of 2 minutes. I immediately stopped the car, let it cool down & checked the radiator. The reservoir was empty and radiator took about 1/2 gal of water (I figured water was fine since the weather is 90 degrees here right now). Suspecting a leak, I also added a bottle of that “Bar’s Stop Leaks” stuff. I hesitantly started making my way home, about 16 miles away. The car was perfectly fine – no overheating at all. Next day, I drove the car maybe 10 miles & again no problems. Yesterday, I went to a friend’s house – about 50 miles round trip. I assumed (I know, dangerous) that all was well … until today. This morning I noticed a small puddle of antifreeze near driver’s front tire. The reservoir was down by about 1/2 it’s capacity BUT the radiator itself was almost full (if it took 3 oz. that was a lot). Now I figure there’s a leak, but if there is then why wouldn’t the system drain itself all the way? Is it unusual to have a leak that limits drainage?
I am also tempted to add another bottle of stop leak but looking around this and other forums, I’m not too sure that’s a good idea. Should I? Thanks much!

First, you should be aware that overheating and failed head gaskets go hand-in-hand with Subarus. You may already have a leaking head gasket which either (a) caused your overheat, or (b) resulted from your overheat. A leaking head gasket will allow coolant to leak into the engine cylinders, causing the coolant to mysteriously disappear…out the tailpipe. Sometimes it will be visible as a puff of white smoke when you start the engine. If the head gasket is leaking, it will eventually require an expensive repair. So, be warned, and look for inexplicably disappearing coolant and white smoke.

Second, the dripping coolant could be from anywhere…a leaking hose, a leaking radiator, a leaking water pump…etc. Take it to a trusted local mechanic and have him find and fix the leak, or you will soon overheat again.

If the engine does overheat again, even with a full radiator, then you have more problems…like a clogged radiator, a bad water pump, a cooling fan that’s not turning on, or an already-leaking head gasket. One of these likely caused the first overheat.

Subaru actually sells this stuff for that purpose. I’d use theirs because it is said to actually do the job:

A leak near the driver’s side tire you’ll need to look at ASAP.
It could be the bottom radiator hose, the water pump or that your head gasket has breached but it could be a heater hose as that routes around that general area as well.
You don’t want to drive that car unless you know where that coolant is coming from.