Can these things really cause significant vacuum leaks?

[mbboy]

I happened to find the article below while searching for the elusive source of a possible vacuum leak in my 81 380sl. According to the article, vacuum leaks can be caused by a valve cover gasket, oil cap gasket, and even the rubber grommet on the dipstick.

Has anyone ever heard of or experienced these things affecting the idle on a 116 or 117?

Pelican Technical Article: Mercedes Benz - Fixing Common Vacuum Leaks

Thanks in advance for your usually enlightening replies

[97 SL320]

It isn't so much an intake manifold vacuum leak as it is unmeasured air. In a air flow type fuel injection system, unmeasured air will let the engine run lean.

[mbboy]

Thanks for the response. But i can't imagine how "unmeasured" air entering the crankcase from the dipstick or filler cap could affect the fuel injection system, since (1) there's plenty of air in the oil pan already, (2) the oil isn't pumped under vacuum into the crankcase or onto the cam shafts and rockers, and (3) gravity returns it to the oil pan.

In fact, I assume that's why the air isn't measured in the first place; i.e., it doesn't figure into the combustion mixture, unless there's something far more wrong with the system -- e.g. a cracked head.

[abiby]

I don't buy it....

If that were the case, removing the oil filler or dipstick while idling would immediately screw up the cars idle.

[C.Doner]

I am wondering how the oil system is connected to the fuel system, other than PCV. The logic has me stumped. Oil leaks don't affect how an engine runs until pressure gets low.