C-13 Acert Cat Water leaking

I have a 2004 C-13 Acert with 695xxx miles on it in a peterbilt 385. I have started loosing water very slowly on n off the the last two months. When I do my short hauls trips estimated 600 miles round trip it will use up to 1/8-1/4 gallon of water. After doing a 2000 miles round trip I have used 1-1/2 gallons of water. I fill it up to the glass eye on the metal resivior/radiator. No sign of water in the oil engine and transmission. I even had it washed deeply through to find leaks turned the bunk n cab heater core valves on n off still hasn't made a different. Truck does not smoke or smell of antifreeze burning. I have done pressure test on radioator caps and combustion tests also it all has passed but during the combustion test it blew antifreeze into the tester very hard all at once like a volcano Mechanic n I can not figure out why its building up so much pressure so quick. I do have the precooler off and goin to the radiator shop for a pressure test and if its pass we are gonna flush system out and put liquid glass in it and put cat approved antifreeze in it unless someone got a better idea cuz im all ears and don't want to pull the heads off.
Is there a way to bypass the precooler cuz it seems like it warms n heat the air up before goin into the air cooler on to the intake. I know I can make a thing for it to by pass with no problem but the question is will it hurt or effect my motor