I've noticed the last couple of times I've driven the old girl that she's spewing some coolant after being parked. Temp gauge doesn't indicate she's overheating. Could it be a faulty thermostat? I don't have the heater core hooked up, just a crossover hose from output to input on the block.

 

First thing I'd do is replace the cap. A bad cap won't keep the system at proper pressure and will do exactly what you're describing.

That said, overfilling a cooling system that doesn't have a reservoir can cause the same problem.

 

Radiator cap is about 3 years old. I just checked the coolant level and it's about 1 inch or less below the hole for the overflow tube.

 

I do hope you're not trying to say that your 3 year old radiator cap can't be bad.

Coolant level sounds fine, maybe even a little high, for a car without an overflow.

 

your best bet is the usual. bring her up to temp and poke around. could be from any number of places, thermo, pump, upper/lower hoses. if you dont see anything drive it around, park it and poke around. get under the car and just wait until you find drips and trace em back to the source. ever once and awhile tracing it back can be tricky as water tends to find interesting areas and paths to follow. had a pin hole leak from a pump gone bad. took me about 30mins to find the freakin thing

 

Where is the coolant coming from? If it doesn't have a recovery tank, then it will blow it out the tube and onto the ground. This will happen more in hot weather. Thats how they were originally. If it doesn't have one, pick one up. Its a good cheap upgrade that is also good for the environment.

 

Coolant coming from overflow tube. Recovery tank sounds like a good idea.

 

No need for a recovery tank. The expansion tank is built into the top tank of your radiator. New cars have gone back to using a pressuized expansion tank and done away with overflow or recovery tanks. IE gone full circle. Get the coolant level correct and a functioning cap and it will not burp coolant even on the hottest days. The level should be about 1/2" above the cores when cold. The rest is expansion space.

 

Any particular pressure rating, etc., for the cap?

 

13lb is stock. If all of your cooling system components (radiator, heater core, hoses) are new, you might consider a 16lb cap.