Dripping/gurgling sound from heater core?

[35Remmy]

Guys, I could have sworn I read a TSB on this...

I'm hearing a dripping/gurgling sound from the heater core area of the cab.

No, it is not leaking anywhere. No coolant loss.

I'm thinking gurgling equals an air bound system, but I would also think that the radiator cap would purge this air from the system?

If not, I could see the water pump cavitating and introducing air into the system.

Any ideas? 99 4.0 OHV.

 

[35Remmy]

OK, so I still have this issue!!! When it does it bad, the temp gauge will fluctuate. You can hear it most when I give it gas, so it's fluctuating with the speed of the water pump.

I went for weeks without losing coolant. Checked the overflow tank yesterday, it was empty!!! Checked radiator itself, and coolant JUST covered the top of the tubes on the inside. WTF?

Filled it...drove about 50 miles today, coolant level didn't go anywhere.

Oh, I can't find any leaks, either. Besides oil, heh.