The way always did it was to take the valve cover off, start the motor and go through and press down on the top of each lifter until I hit the one that was making the noise. Then shut the motor off and check the gap between the lifter and the valve stem top. Adjust if needed. That is the most common way to do it although some of the MB purists may cringe at the idea.

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89 190E
2.6L
Arctic white
Grey leather
Sunroof
Pirelli P400 rubber
Smoked corners