Volvo A35 6wd Truck Coolant Leaving

Where can coolant go in this engine? Coolant was low and engine was overheating and coworkers filled tank up and then run it and now I have it in the shop and added 5 gal of coolant and run it for a bit and there is no coolant leaking on floor and don't think I run it long enough to get it warmed up to open thermostats but the level in tank went down a couple inches in a couple hours. I am working on fixing some air leaks and had air line off coming off of air compressor and could feel or see in coolant coming out of there. Do these injectors have coolant around them? If that was the case wouldn't the fuel be going into the coolant rather than the other way around? I don't know what the year is when I go in to Volvo dealer they say it is fairly old the truck serial # is 2741 I don't know what the engine serial # is but could get it in the morning. TIA Jerry

Volvo A35 6wd Truck Coolant Leaving