I've had two coolant leaks in the last year and neither were because of headgaskets. One was the waterpump, the other the heater core.
The water pump has a weep hole in the snout, behind the pulley, that'll weep coolant once the pump seal fails. It's a almost PITA to replace it and my advice is to seriously consider replacing ALL the hoses at this time, I did and it's much easier to do both a pump and hose replacement together than to do them separately. If you do replace all your hoses make damned sure you reuse the orifice restrictor in the heater supply hose or you will need to replace the heater core.
The heater core is another story. It's a PITA that makes the water pump look easy. You have to evacuate the AC system, take the dash completely out, pull the heater box, hose it out (to get rid of the coolant smell that your wife says makes your car "stink") all to replace a $40 heater core. For giggles I had the dealer quote me a price, $600 labor.
A note on the restrictor, no I didn't forget to reuse mine. The original setup has the restrictor positioned in about the middle of the heater supply hose with a crimp band holding it in place. I reused the restrictor and crimp band. Evidently, I didn't recrimp the crimp band enough and the restrictor got loose, turned sideways and one 5500+ rpm blast later I had a leaky heater core. I went to the dealer to buy the hose, but they don't come with the restrictor installed, it's an added $32 part you have to buy separately. Being cheap I said F that and made one. I used a 1/2" pipe plug, with an allen socket in it. Drilled a 1/4" hole thru the fitting, screwed it into the hose, put a screw clamp (hose clamp) on to hold it and it works fine. Cost me nothing as I had the parts in my bin of spare crap I might one day have a use for. If you had to buy it I suspect it'd be less than $3.00.
Now, how do you know you have a leaky heater core? Simple, if your nose doesn't help (mine smelled like someing rotting, not like coolant), if you turn on the defrost and the windshield fogs up, you have a heater core leak. Another place to look is the heater box drain. It drains thru a tube located at the bottom of the firewall, just to the pass side of the trans tunnel, can see it from above, but odds are you'll have to stick a finger or something in the tube and see if it comes out wet, slippery, and green. (bad visions in my head unrelated to this post, go away visions).
A head gasket is something else altogether. There are tests that can be done, but it requires tools you probably don't have. You can add a dye to the coolant that'll fluoresce under black light, that might help track the location of the leak. An analysis of the coolant can show the presence of combustion chamber gasses in the coolant showing a leaky headgasket. A lekadown test can help too. Another indicators is bubbly coolant when the engine is running, start with the engine cold, pull the cap, start the eingine and observe the coolant CAREFULLY, do not stick your face right over the tube cause it'll burp hot coolant into said face making you unhappy whilst amusing the friends and neighbors. If the coolant is bubbly that's a sign of a leaky headgasket.
That's about it.
Now if you can't do the work yourself all of this is kinda moot anyway.
Originally Posted by slvr2000stang
Holy crap he's right.