If it is the valves the noise is coming from, its most likely that your hydraulic lifters are worn out and don't hold the oil pressure. Makes 12 pieces for your car. They are not too difficult to replace and can be done by any Do-it-yourself'er.
81 300 SD grey/palomino 168K miles
84 190E 2.3 black/grey 64K miles (wrecked)
85 190E 2.3 maroon/palomino 92K miles
88 300E desert red/palomino 204k miles
(made to look like a '94-95)
92 400E desert taupe/creme beige 120K miles
(converted to 94-95 E420 looks)