I have a 1995 Mercedes E320 I took it to the mechanic and he said it has a vacuum leak from the intake to the engine, he said he is still checking it out. He put the smopke machine on it and there was smoke coming out of the oil dip stick tube. In fact you could hear bubbling in there. I'm just curious after detecting a leak from the intake to the engine what is the next step? is he going to have to take the heads out? replace the intake gaskets??