Hello together… on my car there was a problem recently that after hot driving there were noises from the engine compartment. The search was caused by strong vacuum in the area of the valves. The pressure compensation then probably via camshaft seals or valve lids… The symptom has now been fixed (two 5mm holes in the valve lid). But the reason is not. Therefore the question: How does the pressure compensation usually happen ? Can it come to such a large vacuum? In the meantime the engine control light occasionally goes on. The on-board computer does not show any message. OBD II causes the message mixture to lean. Theoretically this can be related to the additional “ventilation”. What do you think about it?