Date registered: Aug 2009
Vehicle: '72 250C, '74 280C, '85 500SEL, '81 300CD.
Location: Tucson, Az.
Mentioned: 3 Post(s)
Quoted: 53 Post(s)
Ahhh! The control valve. Piece of cake! Drain a bit of the coolant, undo the hoses, slip the cables off, two small bolts (either 8mm or 10 mm heads) and pull the entire assembly.
There's a snap ring on each end which needs to be removed. The valves slip out of the body of the unit. Make a note of the positions of the cable levers and the slots in the valve body. Give it a good cleaning, a light lube with some petroleum jelly, renew the o-rings and re-assemble.
When you re-fill with coolant, leave the center hose disconnected at the valve body. Allow the air to bleed out before re-attaching.