Drinking Coolant! HELP Please!

[Zicomba]

Hello folks,
Just happened upon this site tonight and must say I am hopeful with the support that you are showing each other that you might be kind enough to give me some advice.
I bought a JGC Ltd 4.7L V8 in 2001 (new) and in the latter half of last year it started to blow cold air out even with the temp control was up high after a couple of minutes. (For example I'd turn the temp up a few degrees....it would blow out hot air and after a few minutes it would blow out freezing cold air!) Thought it might be the thermostat and had it replaced. (did not solve the problem).
Next it started to loose coolant so I would have to top it up once a month. Had a pressure test done and all positive. Still had to top up coolant. [All of the diagnostics were done at a Jeep dealership!]
Contacted Jeep technical direct and they suggested that I change the radiator cap. When reviewed the existing cap was not holding any pressure.....Happy days I thought - problem solved. WRONG! Now I am replacing coolant at a rate of about 1 litre every 300 - 400 miles. (every 8 days).
I am hoping that it is not the block. The forum correspondence has given some food for thought. My Jeep has only turned 56k miles on the clock.
Anyone out there heard of this one? I have been told that a crack in the block was common in the diesel engines - but those I have talked with have never heard of this happening to the V8.
Your response appreciated.

[dksob81]

Could be a bad head gasket, a blown head gasket will tend to use coolant at a slow rate then steadily get bigger and bigger until it's more noticeable.

Could also be a abd Water Pump, The water pump has a weep hole in it and when it goes bad the coolant leaks out past the bearing and out of the weep hole and the coolant will ussually burn off on the engine at first (not leaving any evidence like puddle or anything). it will also start to get worse to the point you will smell it burning off the engine and will flow out faster.

[BenBB]

I replaced the water pump on my '96, an easy way to tell if it is the water pump is to look under the car, and if it is draining from the bottom center of the engine block, it's more than likley the water pump. Good luck.