well today i got in my truck to head home from work and i put it in gear and i swear i heard water moving?? its the second day in a row i heard this. but no leaks in the cab? is there a line for the heater core running under the dash way up high. the noise almost sounds like a vehicle over heated when it pops and gargles.i was wondering if its maybe antifreeze running through a line? just a thought. terran did you always have this noise ive had it since ive bought mine 4 mths ago and some people have had it since new so thats a little settling i guess

 

Air in the cooling system will do that. Minor annoyance ... relatively easy to eliminate.

 

I don't know it it is the same noise put I always likened mine to an exhaust leak or possibly shorted plug wire. More of a tick tick sound is best I could describe. Death flash was the dealer solution but did not help. When cold was fine after warm up would hear it.In my case it was more noticeable between 35 and 50 mph. Turned out to be the intake gasket. The other sound I have found is the heat shield vibrating against the exhaust manifold. It is more irregular and does sometimes happen at idle.

 

i think your noise is a bit different well for me anyway those noises are a bit easier to recognize.they sound a bit raspier. but this is just strange i cant think of anything that would make a sound of popcorn popping in a vehicle

 

My 1999made the same noise for a while after I bought it used. I was on the forum with the same question about six months ago. It mostly was happening just before the truck got to full operating temp. since then i went back to standard plugs, royal purple, and a CAI. I haven't heard it since. Not sure what fixed it but I think the plugs were the main thing. Good Luck