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  #1  
Old 12-06-2009, 02:07 PM
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76 300D Shifting at high RPMs

Howdy. I'm new here but have been lurking for awhile (in the best way possible). I'm thinking about buying a 76 300D that seems to be in really good shape. Around 120K miles. I would be travelling a ways to get this car and have been talking to the seller in detail. It seems to have two issues.

1) The power booster on the brakes is going out. He says brakes have full power when pressed quickly, but loose power if presses slowly. He's including a power booster with the deal.

2) The trans shifts hard and at high RPMs across the board. It will go into each gear, but it consistently shifts above shift points in all gears. Letting up on the accelerator encourages shifting.

So, if you wouldn't mind imparting your two cents I would appreciate it. My main concern is with the auto trans, but I have a feeling (or more like a hope) that it could just be a simple adjustment (cable?)

Anywho, thanks a bunch!
Travis

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  #2  
Old 12-06-2009, 02:11 PM
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Bad kickdown switch would be my initial hypothesis. Brake problem could be the vacuum pump in addition to the booster.
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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13
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  #3  
Old 12-06-2009, 03:13 PM
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You state: "I would be travelling a ways to get this car". I wouldn't start out on a long drive with a brake problem. If the current owner has the brake booster, ask him to install it before you talk any further.
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Charles
1983 300D, bought new, 215k+ miles, donated to Purple Hearts veterans charity but I have parts for sale: http://www.peachparts.com/shopforum/mercedes-benz-cars-sale/296386-fs-1-owner-83-mb-300d-turbo-rebuild-parts.html
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  #4  
Old 12-06-2009, 04:08 PM
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What would be some other issues assosiated with a vacuum pump? If it's only the brakes that are affected would it make sense to replace the booster becore messing with the vacuum pump? Sorry, for the ignorance, I've been trying to do searches before I ask questions.

Thanks!
Travis
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  #5  
Old 12-06-2009, 07:36 PM
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Location: DFW area (north side)
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These cars activate a vacuum circuit to turn off. Does the car turn off with the key?
You need a hand vacuum pump with a guage to diagnose vacuum problems. If the power booster is bad, that could be the source of any lost vacuum. I'd start with that part since the owner already has it.

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Charles
1983 300D, bought new, 215k+ miles, donated to Purple Hearts veterans charity but I have parts for sale: http://www.peachparts.com/shopforum/showthread.php?t=296386
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