You can replace with older and cheaper valve from older w124 diesel (om603). Then just loop coolant to other side of engine.

This valve was probably used to reduce engine temperature fluctuations and therefore reduce emmisions. It is not necessary on 20 year old car.

__________________
-- Chris

'95 E300, 216k miles, Silver Surfer
'05 E320 CDI, 138k miles
'07 S550 4matic, 69k miles

Gone but not forgotten:

'76 300D, 350k miles?, SOLD in 1995
'75 240D, 300k miles, SOLD in 1991