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'06 CDI '95 E300D '78 280CE
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51 Posts
Discussion Starter #1
My 91 MercedesBenz 2.5D turbo diesel,very rough when shifting,would it damage the transmission?if I connect the transmission modulator vacume line(black) direct to the brake booster,it shifts very smooth,should I leave like this?I owned a few mercedes diesels,they had the same issues. Thanks for your help.
 

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2002 S500, `94 S350D, 93 300SD
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16 Posts
I have the exact same problem, and i`ve read here somewhere that the vacuum pumpp might be the one to check. Let me know what you find out..
 

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ML320E - 260E - 190D
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230 Posts
Hi!
Look on Injection pump - vacum control valve.
If you play with this unit - try reconected back all how was beefore.
Or look on connections to that valve.
Very simply problem.

Regards
 

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93 300E
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12 Posts
it is not unusaul for the large (about 1/4" dia.) vacuum lines at the front of the engine to come loose. The rubber in line connectors dry out with age and do not hold the plastic vacuum lines as secure as they used to.
this will create a signifigant vacuum leak and the transmission will shift hard. If the vacuum pump were bad you most likley would notice a lack power assist for the brakes especially after pumping the brake pedal a few times

Rick
 

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93 300E
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12 Posts
it is not unusaul for the large (about 1/4" dia.) vacuum lines at the front of the engine to come loose. The rubber in line connectors dry out with age and do not hold the plastic vacuum lines as secure as they used to.
this will create a signifigant vacuum leak and the transmission will shift hard. If the vacuum pump were bad you most likley would notice a lack power assist for the brakes especially after pumping the brake pedal a few times

Rick
 

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91 mercedes 300d at shifts rough

Hi I know this is an old thread but did this work? I am having the same problem. Are there other reasons that the transmission would shift rough. my particular problem the transmission seems to be having issues up shifting and down shifting. When it does finally shift it bangs pretty hard.
 
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