i cannot for the life of me get rid of sound of coolant flowing through the heater core, i can start hearing it right around 150 degrees when stuff starts to flow, ive tried every bleeding method, im not losing coolant, not overheating, etc
i had the car on 2 ramps yesterday lifted the tank all the way up, even opened bleed screw on the inline thermostat
i had the tank held up with a bungie cord for 30 min to see if air would come out cold
i had the tank held up high while i rev the engine to 2k for 2 min to see if air would get pushed out
ive driven around with the cap loose
ive driven around with the cap half loose

i remember on my 03 after a coolant repair and refill i would do the normal bleeding procedure and still get the water fall sound for maybe 30 min but would go away right after , this 04 is being a pain in the ***

By-pass flow valve The by-pass flow valve is held closed by a light spring. It operates to further aid heater warm-up. When the main valve is closed and the engine speed is at idle, the coolant pump does not produce sufficient flow and pressure to open the valve. In this condition the valve prevents coolant circulating through the by-pass circuit and forces the coolant through the heater matrix only. This provides a higher flow of coolant through the heater matrix to improve passenger comfort in cold conditions. When the engine speed increases above idle the coolant pump produces a greater flow and pressure than the heater circuit can take. The pressure acts on the flow valve and overcomes the valve spring pressure, opening the valve and limiting the pressure in the heater circuit. The valve modulates to provide maximum coolant flow through the heater matrix and yet allowing excess coolant to flow into the by-pass circuit to provide the engine's cooling needs at higher engine rev/min.



anyone have any tips or come across this issue before

 

I have the exact same issue, waterfall starts right around 150F according to the Ultragauge. I do have the Extinct in-line mod but don’t think that has anything to do with it. I filled the system with an Airlift (via vacuum) and no leaks where found. I had just completely rebuilt the entire cooling system. I also tried the same bleeding procedures you mention but no luck. Same with the cap.
I just recently purchased a new Oem cap from a dealer as I did have a pressure release sound when removing the cap when cold. My next step is to pressure test, not vacuum test the system. I think there is a slight leak someplace that is pulling air into the system when it’s cooling down. I do lose the smallest amount of coolant.
Also, driving around seems to purge the system of air after a little while but not always. I do see temp fluctuations at idle from 170 -199 while I hear the sound. Once I start moving temps around around 180-185. Once the sound is gone temps hold steady.

 

This might be a clue. I have a high mileage car that had the coolant sound in the heater core. After many miles of wonder, I found the small diameter hose from the radiator to the coolant reservoir was badly plugged at a low spot. After the plug was removed, the sound stopped. Maybe worth checking.

 

thanks for the tip.
I only hear mine when I hit the gas

 

ya seems like your having the exact same issue.

I had no problems bleeding the air on my 03. It’s like the air would escape on its own

I have the alisport aluminum tank but that should not cause any bleeding issues.

even if I had a small leak that water sound should not be there right after you bleed the system
I spent a hour yesterday bleeding the system
hoping this morning on the way to work I wouldn’t hear that sound. Nope still there

 

I never had a problem bleeding a D2 before as well. I should also mention that I have heat so it’s not really low on coolant in the core or plugged in some way.

 

i have heat as well and my expansion tank is near full. The alisport tank I have the coolant is always above the sight glass
one thing I don’t like about these tanks you don’t really get a look at the level
and it’s gets bloody hot you can cook meat on it

 

My 00 with 225k on it does it, inline thermostat of course, runs very cool. I don't worry about it. The other 5 don't.

 

Well after 1 hour of topping this to the rim it goes down maybe 2 inch after 20 min. Kept topping it up until it stopped going down. It’s a bit better but still there. I think it needs another round of this. It’s a slow process


cess

 

My Kalahari did the gurgling business right before my heater core clogged up. Then it went silent, and first time I needed heat = I didn't have any.... Back flushed the heater core and white snot looking blobs shot out. Ran the hose thru it until it flowed clear then flushed it the other way. You can quickly tell if it's clogged as one line will be hot and one will be cold. However that's only until after it's clogged. Up until it clogged both heater core lines were the same temp.