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Old 11-09-2011, 12:45 PM   #25 (permalink)
ConnClark
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Join Date: Jun 2008
Location: Richland,WA
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Das Schlepper Frog - '85 Mercedes Benz 300SD
90 day: 23.23 mpg (US)

Gentoo320 - '04 Mercedes C320 4Matic
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Quote:
Originally Posted by Old Mechanic View Post
I know in the old MB sedans in the early 80s a vacuum leak in the central locking system would allow the engine to run on the air passing through a 1.5 MM ID vacuum line in one of the doors. In 82 they eliminated the throttle butterfly in all of their diesels and claimed a 7% increase in efficiency from eliminating all manifold vacuum completely.

Unicorn.

regards
Mech
Ahem, the reason why the Mercedes diesel sedans in the late 70s and early 80s would continue to run with a vacuum leak is that they used the vacuum to shut off the engine. A severe leak would drop the vacuum enough it couldn't pull the injector pump to the off position. There was no butterfly valve on the diesels. The diesels had a dedicated vacuum pump. The gains made in 82 were due to an improved cam with more lift that allowed the engines to breath more.
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