Both engines are om617.952. One is sedan another is wagon.
Last winter, I can not start my sedan when temp reached -3 without block heater. It was not adjusted in the past 6 years told by PO.
After adjustment, I can start the engine at -11 without block heater plugged.
Clearly the valve adjustment , in my case , actually increased the clearance. After adjustment, it sucked more air, improved the compression, made engine easier to be started.
Slightly increasing the valve clearance on the intake valves can improve effective compression, it is also something that is recommended by MB for very cold climates. There might be some drawback, less performance at full load probably.
More air means more power, why it is a performance drawback?
"The clearances get tighter mainly due to Wear on the Valve Faces and their seats that causes the Valves to move up and close the clearances.
according to your response, to increase the clearance is to push down the valve stem, without change the valve and head, how to compensate the worn between valve face and head after increase the clearance?