'89 W126 Monovalve question, checkball??
 

Still working on my 'up to speed heat'. I wanted to ask a specific question so I started a new thread. For back info look for my "weird heat problem thread'

I am getting heat at idle and around town. 60 mph plus, the heat turns luke warm at best.

I have pulled monovalve piston(brand new) out looking for a blockage. Under the piston, down low in the housing looks like a check ball(valve?) of some sort. Is it supposed to be there? could this be my blockage? It is not siezed up and looks to kind of float around down there....anyone??

from what i can tell, the coolant flows down towards the electric pump and keeps the coolant from backflowing when the pump is off.