Coolant surge sound in heater core
 

I have a 2000 classic k2500 w/7.4l. When I accelerate and the water pump increases in rpm I can hear the coolant surging through the heater core. Would this indicate low coolant level or something else? Any ideas?

I hear it too, but my heat still works. I guess maybe there's an air pocket in there that gets pushed around?

yeah i have it

add coolat and burp the system. when you add the coolant hold the rpms at like 1500-2000 and all the air will bubble out. thats how i fixed my problem.

There are valves to shut off the flow of coolant through the heater block. Suspect that you have one that is sticking and not fully open or closed. Should not be hard for a mechanic to check.