Coolant Leaking

[ruijay]

Hello community.

I have bought a toyota 4runner 98 recently with around 160k.
Truck runs great but I have encountered a small problem with the coolant leaving from underneath the engine by the passenger side. The first time I inspected it, I found few drips of coolant by the back of transmission but I know it's coming from somewhere else. Yesterday evening, I blew some air on the water hose between the pressure cap and the reservoir, went underneath the truck to see if I could find anything, and I did find a line of coolant but I am not sure what the black housing is called. I took a picture of it and I was wondering if someone knows what is called and if it possible to be the cause of my leaking headaches.
hxxp://i60.tinypic.com/29eiwrl.jpg

 

[ruijay]

That was my oil pan.
I found my coolant leak source. It was coming from one of my freezing plug on the driver side of the engine. I could barely see it and I could only touch it using a long flat screw driver. I will have to jack up my truck and see if I have enough room hammering the screwdriver to remove that rusty boy. If not, I will have to take it a mechanic and get an estimate.

 

[ruijay]

Last update:
Because of the complexity of the job and the risk of ruining the cylinder while removing the old&rusty freeze plus, I decided to give the job to my mechanic. He charged me $230. He was not able to remove the old plug without making a whole first so he could pry it. He tried 3 different freezing plug sizes from the auto parts shop before he finally settled on the freeze plug with expendable rubber. He used red locktite sealant before tightening it. Everything looks good and there is no more leak after two days of driving. I read somewhere that people don't like the expendable freeze plug because they don't last long, so I hope it does not fail on me.