Replacing hydraulic lifters in an M102 or M103 is an easy and inexpensive job, but first you need to be sure they need replacing. If they only tick until the oil pressure rises then they are fine. If they continue to tick after the oil pressure rises then they are worn. I replaced mine recently on my 190E (at around 220,000km) because they would intermittently tick until the engine reached full operating temperature. With new lifters (I replaced them all) the problem is fixed. On a cold start they may still tick for a couple of seconds before the oil pressure rises. This is due to one or more slowly leaking down while holding a valve open. Our 300TE at 180,000km does the same. If you decide to replace them, just remove and replace one pair of rockers at a time. This avoids the need to remove the timing chain tensioner and reduces the risk of replacing parts in the wrong position. All valve train components must be returned to their original location.

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107.023: 350SLC, 3-speed auto, icon gold, parchment MBtex (sold 2012 after 29 years ownership).
107.026: 500SLC, 4-speed auto, thistle green, green velour.
124.090: 300TE, 4-speed auto, arctic white, cream-beige MBtex.
201.028: 190E 2.3 Sportline, 5-speed manual, arctic white, blue leather.
201.028: 190E 2.3, 4-speed auto, blue-black, grey MBtex.
201.034: 190E 2.3-16, 5-speed manual, blue-black, black leather.