I've been having constant waterfall noises despite all cooling system components being new, except the heater core, of course. I've pressure tested and bled the truck dozens of times with no luck. So yesterday I filled the heater core with white vinegar and let it soak all night. Today I rinsed it all out and put everything back together. Result: Significantly reduction in water fall noises but it's still present. Like... if before it was 100%, now it's 20% and sporadic. I think it could use another soak but was wondering if I should try something a little stronger? Any ideas what might work well? I'm assuming what's left is stuff vinegar either has no effect on or needs more time to dissolve.

 

your problem sounds more like trapped air in the heat exchanger.
Did you back flush then forward flush the heat exchanger? that's the best way to dislodge anything trapped in there.
Be careful of adding fluids that might be too caustic on aluminum.

 

I agree about the trapped air. I think it's trapped though by some of the galleries/passageways being plugged with sediment or crusted Dexcool. Hence the vinegar soak.

And yes, I flushed it both directions.

 

I still had waterfalls in my truck as well after bleeding and there's been very few trucks I've not been able to bleed completely...However, I was able to get rid of the sounds with a vacuum bleeder. During the vacuum bleed I actually found out the nipple for the overflow on the radiator was seeping. That replaced and a vacuum bleed done with new BMW blue coolant yielded a lower operating temperature than I've gotten before and no waterfall sounds.

May want to give it a try, I bought mine from Harbour Freight for around $45. It is made by Mityvac.

(edit) https://www.harborfreight.com/mityva...ump-39522.html
It seems as though they have their own brand as well: https://www.harborfreight.com/brake-...kit-63391.html

But I do not have experience with it....

Good luck buddy