Disconnected a 2 piece "connector" on a harness that is located right next to the monovalve but is headed towards that aux water pump...it looks pretty easy to find... ( looking at the picture was helpful --see below -- seems to be the harness that I disconnected!)
Needless to say that did NOT solve the problem, but what did was a monovalve repair kit. This on teh higher mileage 300SD. In all fairness, this car had the problem of "continous heat" and not the intermittent heat.
The other car has more of that intermittent problem so I will try to disconnect the aux pump on that one and report back my findings.
I should have disconnect this thing a long time ago as we barely need heat in California. Here's a good picture from fastlane: