overheating on 2005 Chevrolet Express 3500

overheated after a 3 hr trip last night, expansion tank is empty, still some anti freeze in the radiator. I've owned it for 2 yrs. and have occasionally smelled anti freeze but have found no evidence of a leak. No steam/smell from tail pipe either.

1 answer
I would get your car's cooling system really inspected, you have either have a leak or the engine is consuming it, both of which need repair.