Is this unconnected vacuum line, that apparently leads to the elusive thermovalve. There is another nipple underneath it that can't be seen in the photo that is blocked off (modified) that supposedly used to run to the regeneration valve, in earlier versions.

Checking on-off ratios today with this line simply squeezed shut, my readings stabilized and rose from around 10% at idle to around 35%. Readings at 2k rpm were in the mid 40's%.

I'm going to forget about finding the thermovalve and close this line shut -- IF no long term damage or effects result. Can a tech please chime in on whether this is desirable or not? What's the thermovalve for in the first place?

As I stated in a previous post, the valve used to be located on the front of the head on earlier versions ('87-'89? ... '86 manual does not show it there). In its place is the coolant bleed screw on my 103.

TIA for any help in this area,

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-Paul-
'01 E430, Sport 72,000 mi
'98 C280, 126,500 mi