My dads 12V sounds like there is water in the turbo? When you accelerate, it sounds like there is fluid splashing around somewhere on the passengers side engine compartment?

Any ideas?

 

Sounds like an air space in the cooling system. The air going through the heater core will make the sound you talk about. Start the engine cold with the radiator cap off and top off the radiator. Let it run for a few minutes to let the pump push all the air into radiator and top off again. Shut down and replace cap once the air is out. The cooling system is quite large and an air bubble won't really hurt the beast much but the sound is worrisome.