What does the stainless steel plug do in the E3D Kraken cooler block? In the E3D Kraken cooler block, there is a big, 10&nbsp;mm grub screw, along the side of the cooler block.

I watched the entire Kraken assembly video:


                
            

There was no mention of this very thick grub screw. The E3D Kraken assembly wiki page may refer to this part as the "stainless plug".

Does the depth of the screw inside the Kraken heatbreak affect the effectiveness of the water cooling?

Why was it included in the design at all?

I'm asking because water frequently leaks out of this pore for me, ever since I had to repair some damaged tubing. Additionally I often have to use an extra fan when printing at high temperatures. I'm wondering, before I epoxy this grub screw into place, whether the amount it is tightened into the Kraken has some advantages or disadvantages.

The video shows the part already assembled on the Kraken. This is what the part looks like - it is much larger than the screws used to secure heat throats.
The connecting channel between the two brass barbed hose fittings needs to be drilled out.  To open that channel, a hole is drilled into the side to connect the two top holes (which have the brass fittings screwed into them).  The hole doesn't need to penetrate both sides, but it must get through one side.

The grub screw seals the hole.

Instead of using epoxy to seal in the screw, you could use the PTFE (Teflon) white plumbing tape.  It is specifically designed to seal threads.

If I remember, you can thread it in as tightly as you like.  It won't interfere with the water channel.

I have a Kraken, and I looked at how to make another one.