Severe Coolant Leak

[mitchellfried]

This morning when I started my truck and came back about 5 minutes later I found a big puddle of coolant below my engine. It leaks to the point where its almost a steady stream. It only leaks when running. It appears to be leaking between the fan and the block. Anybody have any ideas?

[mitchellfried]

I'm guessing water pump seal?

[madpogue]

Or maybe thermostat housing. Gotta look/feel around that neighborhood.