Hi guys I am new to this but am in desperate need of help, I have a 08 Titan 4x4 with 162,000 miles. Over the last couple months we have been smelling what smells like anitfreeze, truck is not overheating at all, would lose about a half gallon a every few weeks. Noticed it had antifreeze all over the plastic cover on top of the engine. We checked could not find any leaks anywhere. A couple weeks ago we put a new radiator cap on it. A couple days ago we drove it not even a mile when we got home heard a hissing sound and water all over on the ground under it, still was not showing to be overheating, Noticed this morning it was bubbling up under the new cap so bought a new cap with the pressure release, now it is bubbling out the release & filling the cap. I need help what could possibly be causing this.