Running water sound

I have an 89 C1500 and it is making a strange noise. When I accelerate, I hear water rushing through the heater core. It rushes for about 10 seconds then stops. It does it often. Any ideas as to what is causing this?

Dave

That can happen when you don't have your radiator quite full, and you get air bubbles. Fill it up with antifreeze/water mixed and it will stop.

there is a restricter in the heater hose that can cause this. It is not a big deal just a minor inconvienience...both of mine do it but it doesn't bother me enough to jack with it.