Rear brake bleeder issue

[forgiven]

I needed to replace my fluid in the rear brakes due to boiling. In the process I was trying to use the rear bleeder. When I turned the lock nut on the bleeder the whole bleeder started rotating out. Tried numerous times to unfreeze it. First what kind cross over and two when I go to put it in I know that it threads in but I don't see a way to tighten it.

2010 ec300 btw.

 

[gasgasman]

There's no lock nut on the bleeder. It just unscrews.
You should only have to loosen it a couple turns for fluid to come out.

You can see in the pic below how unseating the nipple opens the port in the caliper. The fluid then travels through the hole out the center of the nipple.

 

[forgiven]

Perhaps the port is plugged. Fluid was coming out around the threads. I have had the plastic cap on the whole time me.