In my 1987 model 4runner, at higher RPM's I hear the sound of water trickling in my dash. My original thought was that I had air trapped in my coolant system, but I have followed the directions I found on here for purging the system and the sound is still there. I know that the hot water valve under the hood is stuck and does not move when I change the temperature selector from hot to cold (I do hear the "flapper" move though). I do get warm air from the vents when I run the fan with the selector on hot, though not as warm as I would like. Does anyone have any ideas about what might be going on?
Thanks in advance,
Rick

 

unclip the heater valve selector wire from the valve on the engine side of the firewall and manually move the valve open or closed and see if the sound goes away. start at that valve first

 

I hear the same thing in mine except mine only does it between 2-3k RPM in first gear pulling out of the driveway in the morning, after that, no noise.

 

That is a great idea. It is frozen, but I can just bypass it.

 

yes but you will have no control from inside the truck. it wont hurt or damage anything though.