Coolant loss

[Soulreaver0102]

Hello everyone. Been a while since I’ve posted. I have a 2012 cascadia 2250 demandate programmed by someone on this site. Just shy of 698,000 miles. I have had coolant loss lately and thought it was from my heater core hose leaking a little bit from hose connection as I have seen it leak from there. Well yesterday morning I topped off the coolant and hit the road. I went give or take 100 miles to my drop location dropped container and bobtail back. I made it less than mile and check engine light came on followed by stop. So I shut it down popped hood and was low on coolant. Added 1 1/2 gallons of coolant. No leaks anywhere. Not even heater hose connection. Hit the road made it back. This morning checked coolant 2gallons needed to fill. 40 miles add 2 more gallons. Total between yesterday and today to and back from shop I’ve ran through 6 gallons of coolant. Mechanic wants me to bring it back after he finishes the engine job to further diagnose. There is no external leaks. He pressured up the system with pressure loss of course. He thought compressor maybe bad. No sign of coolant in air dryer purge valve area or in tanks. Then he said he smells it around the turbo and thinks maybe actuator. But says that kind of coolant loss it should be at least leaking from around the turbo. Nothing is being blown from exhaust nor does exhaust have a coolant smell. Did block tester for head gasket and it showed nothing. Egr cooler was welded shut and put back on during demandate. I am not making any oil and oil looks good. I will drain a hair off tomorrow just to make sure. Any things else I can check or a way to check if actuator is leaking or any insight. I appreciate any ideas. Thanks.