I just purchased a 1997 f150 4.6l 4x4 and when I accelerate there is a water pouring sound under the dash. I don't have any leaks. Could it be water flowing thru the heater core. Does anyone else have this sound?
Thanks.

 

turn the a/c on, give it 5min of driving, look to see under the truck if the a/c is dripping under the r/h firewall. no drips means the a/c vent is plugged. If it smells like a wet sock in the truck its plugged for sure.

 

Mine does too.. Mine will drip water from the tube so its not clogged. Must just be normal. I have no problems with my hvac system. Coolant was flushed 3k miles ago.