Coolant Leak-2001 Mitsubishi Eclipse 4 Cyl

I was driving and noticed that my temperature gauge went close to the warning zone so I blasted the heat and it went back down. When the car cooled I popped the hood and noticed that the coolant reservoir was pretty close to full but I couldnt see any coolant in the radiator. I filled the radiator with water for now but it looks like it gone again. I cannot spot any actual cracks or leaks on the hoses but I did spot a puddle of coolant in the groves on top of the transmission. The closest hose I can spot next to the puddle is the lower radiator hose but I really do not know too much about cars. I also noticed a hissing sound today coming from the radiator cap, which I am going to replace. Does anyone have any ideas on where the leak could be which is causing the puddle on top of the tranny? Thanks!

On the firewall (the passenger compartment divider) there are two pipes going straight in(4 if you have a/c). Look and see if those might be leaking on to the transmission. It is likely the heater plumbing from the engine that has the leak. Best time to check is to get the engine hot, turn it off and look along the heater lines for wet spots.

Take the car to a mechanic and get fixed before you damage the engine.

FYI, you should never add plain water to a car’s cooling system.

It is a lot better to add plain water than let it run dry. You can add antifreeze after you get the leak fixed.

True, but adding water is not a solution to the problem.