Hyundai Repair: 100 percent leak down in coolant, 2003 hyundai elantra, bumper to bumper warranty

Question
Hello, I have a leak down in coolant.  It is leaking between cylinders.  Has bad head gasket, compression test shows cyl #1 70PSI, #2 45 PSI, #3 20 PSI, and #4 at 25 PSI.  What would cause the leak in the coolant or what would cause the car to completely shut down?  Is this a costly job?  If it is a 2003 Hyundai Elantra, 2.0 L, with 44,000 miles on it will that be covered under warranty?  Thanks for your time

Answer
Usually, damage to the engine that causes coolant to leak between cylinders is caused by overheating, usually due to a defective thermostat.  In every case I've seen like this, the head was warped so badly that the cylinder head itself needs to be replaced.  

The good news is that if you're in the U.S., this should be covered by your 5 year/60,000 mile bumper to bumper warranty.  If not, you're probably looking at $2000 or so in repair costs.