In doing some work on the '87 Wolfsburg last weekend describing that and the
troubles I encountered would require several more posts) I discovered that
someone had broken off the small house and nipple that comes out of what I
would call the top of the thermostat housing, but which parts places call
the thermostat cover. They had stuck a nail in the hose and some epoxy
around it, so that it plugged the hole left by the broken nipple, and also
restricted anthing that would have flowed through this small hose.

I got a replacement cover, but when I looked inside I became puzzled. The
bleed screw sits on top, and this nipple seems to come from the top near the
bleed screw, but the only hole is less than a mm in diameter and looks like
it is only for bleeding air. So what does the hose do that comes out of this
nipple? It goes to the rail that surrounds the engine compartment. The hole
looks too small to carry any meaningful amount of coolant. What's going on
here?

Ed in CT