I have a 2004 Murano with 130,000 miles and it is inconsistently leaking coolant. A couple weeks ago I checked the coolant reservoir and it was pretty dry. I brought it to a local mechanic who pressure tested the coolant system and was unable to find a leak. He suggested the inconsistency may be a sign of a bad water pump. I then brought it to a different mechanic who pressure tested it and said the head gasket needs to be replaced.
This seems a little bit curious that there were two different diagnoses of this issue. My little knowledge of cars would lead me to believe that if the head gasket was damaged then the first pressure test would have revealed a leak somewhere in the system. Also, there is no white smoke in the exhaust, and there does not appear to be any coolant present on the oil dipstick. However I have little knowledge of this issue and car mechanics in general.
Can anyone shed any light on this problem? Any thoughts on how to proceed since I think there is a significant price difference between a water pump and a head gasket?