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Old 11-09-2011, 05:23 PM   #29 (permalink)
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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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Originally Posted by Old Mechanic View Post
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.

Looks like we both need schooling.

Why a throttle plate on a diesel engine? - PeachParts Mercedes ShopForum

In 1982 and after, the 240Ds had a throttle plate for increased EGR flow. Years prior to 1976 had a throttle plate for vacuum for the injection pump governor. The 300Ds, 300SDs, 300CDs, and 300TDs didn't.