Subaru Repair: overheating, legacy outback, head gaskets

Question
We have a 1999 legacy outback 2.5L engine that intermitten overheatng problem. The water pump went one year ago and was replaced. Shrotly after that this overheating problem started. It does not overheat all the time, usually have to run the engine for more than an hour, the length of my commute. I've replaced the thermostate several times, put in a new radiator. Could this be a leaking head gasket or a bad pump? if it's the gasket how do I know which side and what is a reasonable cost?
Thanks for your help

Answer
Hello Steve,

The easiest thing to look for is evidence of  an exhaust smell in the coolant overflow bottle.If the bottle smells like exhaust,fuel,or sulfur its the head gaskets.This is very common for the 1996 to 1999 1st generation EJ 2.5l engine.The head gaskets need be done both sides when repaired.At our shop the repair starts @ $1500.00 and goes from there depending on its exact needs.I hope that helps

Justin
All Wheel Drive Auto