HiCustomer Welcome to JA. I am Buddy, and i will try and help you out. How much coolant loss are you getting out of overflow hose?Did this problem just start or has it been getting worse over time?
It losses 1and1/2 gallons on 4,000 miles. The hoses that go to the radiator were hard so i changed them.
If coolant temp is normal it sounds like you are possibly getting compression in your cooling system. If you have a radiator pressure tester with adaptors ,you can pressure test the radiator cap and make sure it is opening up at correct pressure. Then you could hook it to your surge tank and run your engine to operating temp and monitor pressure.If pressure is getting above 15 psi, you are getting pressure in there from somewhere. First you would need to bypass the air compressor and see if it is causing the problem. You could remove discharge line from air compressor and bleed air down. Run engine again and see if pressure rises above specs. If it does, then you more then likely have a head gasket blown or head issue. If head gasket is blown i would check liner protrusion and make sure it is between .004 and .007 . You can also do most of these checks without a pressure tester. You can get a clear bottle of water and put your over flow hose in it from surge tank and run engine up to operating temp on fast idle and see if you are getting air bubbles in bottle. If you are getting bubbles, you are getting pressure in cooling system. I hope this helps you out.If you have anymore questions, just ask.
You are welcome. Let me know what you come up with. If you have anymore questions, just ask.