Tackering at 406

Hello, I have been driving a 406 for half a year, year 97, 1.8L. 16V 110hp. I am actually very satisfied with this car. However, since a few he gives unusual noises of himself. The buzzing when the electrics are switched on has already been identified by my workshop as a defective reversing valve actuator. When driving, however, as soon as the engine gets warm, there is still such a slight tacker at regular intervals (not constantly). Filling in oil and can also be heard clearly in the interior. This tackering increases in 3 speed levels, depending on how much gas I give. My workshop could not help me any more and said I should go to the contract workshop. However, this one has only one week off, which is why I am a little nervous, because I don’t know if I should put the car off better by then. Does any of you still have advice? Thank you in advance Oscillator