I have a 92 300e ,103 motor, after a complete valve job, now there is a tapping noise, louder when the motor gets warm, noise is coming from the rear 5 and 6 cyl, so far I have replaced all the lifters,change the oil,replaced #6 exhaust rocker, replaced oil delivery tube, and noise is still there, also checked for exhaust leaks, otherwise the motor runs smooth. Going to replace the camshaft next, but dont really want to spend the money if this doesnt cure the noise, would rather sell the car, has anyone had this problem? MB techs ,I would greatly appreciate any input, thanks!