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Old 11-09-2011, 04:27 PM   #28 (permalink)
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Originally Posted by ConnClark View Post
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.
Ahem, the information I provided was from very ancient memory, when I was working for Mercedes in Houston Texas in 1982. It was a factory bulletin, so while you may disagree with me the information was provided by MB. Now memory is a fickle thing when age starts to degrade the mental pathways, but I do remember Mercedes (not me) claimed a 7% increase due to the improvements made around 1982. Part of the improvement was due to the elimination of the throttle plate.

Engine braking or drag? - Page 2 - PeachParts Mercedes ShopForum

Sounds like this fellow knows what he is talking about. I remember they started using a vacuum pump driven by the timing chain around 1982. Again old memory. After that they just controlled engine speed and power through the injection pump exclusively. Not saying the camshaft was not a part of the improvement just saying what I remember from the factory bulletin covering the changes from the previous model year.

Maybe you have better information than a factory service bulletin?

I was working at Intercontinental Motors on Kuykendahl road which ran parallel to the Interstate running north from Houston. I 15 if memory serves.