when I first start the truck up, and sometimes later after warming up there is a sound like a tranquil waterfall up inside my dash. My wife says it is there for stress relief but I'm wondering if that is a problem. any ideas would be helpful.

 

sorry, and its a 95 disco I

 

You have a bad thermostat or have air in your coolant lines or your coolant level is dangerously low. If my wife was in charge of diagnosing mechanical problems we would be without means of conveyance.

 

With the engine cold add engine coolant, there is a "X" inside the coolant over flow bottle, that "X" needs to be underwater.
Do that and the noise should stop.
It is doing that because you are low on coolant.

 

What hasn't been said is that 1, you have a coolant leak and 2, you need to bleed the air from the system, do you know how?

 

no I do not, please tell me. I am fairly mechanically inclined and plan on doing a lot of the work on my disco myself.
I did add some coolant and it got quieter but didn't go away.

 

Top off the coolant again and then with the cap off the radiator overflow tank turn on the heater and idle the engine for 30 min, then replace the cap, turn off the engine.
The noise should be gone.