What is this for??? (Beneath the water pump)

[Triple13]

Can anyone tell me what this tube is for and what might have leaked from it???
The other day I noticed some dried up substance that seems to have come from this fitting. Also, there appears to be some kind of sealant/glue substance around the fitting that may have melted???
Has anyone experienced this yet?

 

[warp9.9]

Green and yeller are coolant green to top of radiator and yellow to the bottom right rear of the radiator behind the chicken cage. Red oil breather between oil tank and engine crank case gases flow thru it plus allows the gravity oil tank to feed .

Not sure if the little hose is leaking which is usual. But I do notice a fare bit of snot (clear silicone) near where the little nipple goes into the thermostat housing. In pink below

I'd bet the hose and clamp or the snot for sure. You can see the droolings on the engine case right below the front of the oil tank.

 

[Triple13]

Thank you for the great info

 

[warp9.9]

Thank you for the great info

A new morning thought check the hose coming from the overflow bottle and how much is in the bottle. If its leaking you can see from the picture that it would run down the hose and drip in the same area. And check you radiator cap for the heck of it.