Buy a water pump. That’s what’s leaking from under the fan hub. When you replace aluminum washer under bolt of “protruding thing” otherwise known as cam chain tensioner make sure you bleed it. Once you bolt front cover back on and you’re just about ready to close things up, take an oil can with some fresh engine oil in it and squirt into the small cavity the tensioner sits in til it’s overflowing. Take a screwdriver and pump the piston in and let it spring out and keep doing it until you feel strong resistance when you do it. You will see bubbles coming out too. Once the bubbles stop and you feel the resistance get heavy, it’s bled. You don’t want to miss this small but important detail.
You might want to check the condition of the plastic chain guides and tensioner rail along with cam chain, oil pump chain and sprocket's for cam chain on the crank and the top sprocket bolted to cam while you have the cover off. Look for wear on the rubber part of the tensioner. Also take a look at how much slack there is in the oil pump chain. I took apart an engine with 60k on it and oil chain was stretched and had enough slack to just about hit the casting on one side. I had a bunch of shims but when you have to use too many like over 5, get a new chain. New chain was needed in this case with one shim. The cam chain, tensioner and plastic rails in that engine were still okay. These are a little more involved to change. If you decide to do this set engine cam marks to top dead center. Do not just leave engine in some random position when and if you take the cam chain off.