New sound/noise
 

96 F150 XL 302. Started up the truck to day to move in to put on a new ignition coil. (replacement of original with MSD 8227) . I started to hear a "gurgling" sound from behind the dash, the higher I got the rpm the more it was noticeable. I didn't take it out for a drive to check if it went away. There are no leaks anywhere. I am assuming this is coolant going through the heater core in some sort of irregular fashion. Coolant levels are fine. Has anyone else heard this gurgling in their truck? thanks for any info.
Phil

Well, after letting the engine run with the RPM's up a bit the gurgling sound went away. It was as if the heater core was refilling itself or something. Maybe it just means that I have to flush my cooling system, some crud was causing a partial blockage or something so I was hearing the fluid move through it for the first time. Sorry to be an alarmist but I usually ask here when some new issue comes up because you guys have been so helpful.