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The coolant filter discharges to the degas bottle which isn't full of water and is the suction point of the pump, so I don't see how that could increase the pressure in the degas bottle.
Perhaps you are getting a lot of coolant bypassing the radiator thru the coolant filter which is raising the water temp & along with it the pressure.
I design large building heating/cooling systems utilizing water for a living. Very similar system. Typically the pressure at the pump suction (degas bottle on our trucks) is a constant and doesn't change with pump operation. the pump is sucking & pushing back into the same place so the pressure equalize. It only changes with temperature. I'll try and sketch up a simple diagram tonight when I get home.
Need to install a pressure sensor on my degas as I run similar conditions (big load, high temps, long grades).
Dave,
Where in the Degas tank do you plan to put a sensor? I have seen them in the top half. BUT, that's an "air" space and as such is compressible. Which could cause inaccurate readings? However, the entire system technically should be at the same pressure since it's a semi closed system? Just curious. B.
By definition the system cannot have the same pressure throughout it while running. If it did there would be zero flow. The suction side needs to have lower pressure then the discharge side. FiveO, you forgot about the larger source for the suction side, the radiator.
Not counting the bypass filter the heater core loop is a fixed system.. I mean whatever is pumped into it comes out right below the degas bottle and right back to the front cover. The degas bottle recieves it in flow from the 2 overflow hoses.
As shown in my quick little pressure curve experiment, the water is adding significant pressure to the degas bottle.
Now that I am writing this I realized one little glitch in the test I ran, I had the heatr control valve closed so to deadhead that line.
By definition the system cannot have the same pressure throughout it while running. If it did there would be zero flow. The suction side needs to have lower pressure then the discharge side. FiveO, you forgot about the larger source for the suction side, the radiator.
Not counting the bypass filter the heater core loop is a fixed system.. I mean whatever is pumped into it comes out right below the degas bottle and right back to the front cover. The degas bottle recieves it in flow from the 2 overflow hoses.
As shown in my quick little pressure curve experiment, the water is adding significant pressure to the degas bottle.
Now that I am writing this I realized one little glitch in the test I ran, I had the heatr control valve closed so to deadhead that line.
Drew up a schematic of the system based on the 6.0 Bible and what I see on my truck. Helps see how flow goes thru the various engine components. Will try and do a legit one in CAD next week while I"m at work.
I guessed in some pressures to help illustrate how pressure will rise at the pump & decrease thru the various components. They are not real numbers, just my best guess.
Where in the Degas tank do you plan to put a sensor? I have seen them in the top half. BUT, that's an "air" space and as such is compressible. Which could cause inaccurate readings? However, the entire system technically should be at the same pressure since it's a semi closed system? Just curious. B.
Bruce you would tap into the top of the degas. There's a flat surface on the driver-side that is pretty thick right behind the cap.
Since the weight of air is negligible the pressure in the airspace of the degas tank will all be at the same pressure. Water does have weight and will add pressure as you add "head of water". Typically 2.3ft of water equals 1psi (varies a little bit based on the water temp).
And yes those pressure changes are immediate with RPM change.
Like I said originally INTERESTING.
I was thinking the heater core supply came off the water pump more directly, but reviewing your diagram and the 6.0 Bible most comes from the passenger side head and the 2 coolers.
I guess I need to try my little experiment with the heater on full to got max flow thru the heater core, and see if that changes the pressures.
Drew up a schematic of the system based on the 6.0 Bible and what I see on my truck. Helps see how flow goes thru the various engine components. Will try and do a legit one in CAD next week while I"m at work.
I guessed in some pressures to help illustrate how pressure will rise at the pump & decrease thru the various components. They are not real numbers, just my best guess.
Great schem ... snipped and saved for posterity. Big Thanks!
Opening or closing the valves may change the flow through the system, not only of the compressible gas but also of the incompressible coolant? The location of the sensor measures both the static and dynamic pressure in the line, which may not be the same as the relief pressure of the cap. So you're potentially changing the conditions at the sensor, not knowing what else is changing in the system.
Might be interesting to pinch off, or otherwise close, the flow from/to the degas bottle through that line altogether so that the sensor is only measuring static pressure in the degas bottle, just to see what changes? Leaving the valve to the filter open might allow the gas in the radiator to vent back into the cooling system. I wouldn't want to allow the gas to continue to build up in the radiator for any period of time.
Bill
