Nissan Repair: water leak, head gasket leak, nissan truck

Question
There is a small tube/hose extending from the firewall (under the hood)near the heater a short distance (3"). Water will drip from this hose when the engine gets hot and in about a week I have to top up the radiator or the engine will overheat. What is causing this water to drip?

Thank you,
Tony
1995 Nissan Truck, 4 cylinder, 155,000 miles. This is the 1st problem this truck has ever had.

Answer
Tony,

The hose you are discussing is where the condensate from the airconditioning evaporator core leaks out.  This is normal.  However, if the liquid that is leaking out has antifreeze in it you have a bad heater core.  So, check the fluid for signs of antifreeze and if it is replace the heater core.  If you just have water leaking out and you are using the airconditioner this is normal.  Other causes for the loss of coolant are a bad pressure cap.  A small leak in the system that only really gets going when the vehicle is in motion.  You can get under the truck and look for signs of small leaks by the sediment left from the coolantt as it dries.  Look under the waterpump as this is a place engines start to leak with the year and the number of miles.  Lastly, and you do not want this, is a bad head gasket.  If there is steam coming from the exhaust or it smells like coolant at the back of the truck you need to have the system checked for exhaust gas in the coolant.  This is how they determine if there is a head gasket leak.  You can buy the kit yourself and follow the directions and it only runs about $30 bucks.