My Yukon sounds like it river running through the passenger side firewall.

It begins to flow soon as the engine begins and runs rapidly throught the right side floorboard. It subsides after a period of driving but after truck is settled or turns you hear hear the internal river racing again. All fluids are maintaing levels and vehicle does not overheat. Just a big mystery to me as to what is the source of this raging river inside the vehicle. Never heard of such a thing!