Lately I have lost coolant but could not find out where it was going.The heater and temp gauge were giving me trouble for awhile then I added collant a few times to keep the bottle full and everything was better. The truck was good as new like it has always been since I bought it. This morning when I went to start it fired right up like always but had a horrible ticking sound. I closed the hood and took the old lady's toyota to work. When I got home I checked the oil and it was at the bottom line so I unscrewed the filler cap and found green sludge/snot under the cap and thick in the filler hose. I guess it is a gasket leaking coolant. I had a new intake manifold installed about four months ago and would love to blame it on faulty mechanic work but I dont know how to tell if that could be the case.

 

What engine, and what has been done?