I have a 1982 240D. Tonight, while driving on the freeway, I went to apply the brakes and the car was very difficult to stop. When I arrived home, I turned off the key, the engine continued to run, and I had to use the emergency stop under the hood. After reading several posts, I suspect that the vacuum pump may be bad. Does anyone out there have any ideas about how to determine for sure whether or not the vacuum pump is bad, and for that matter the exact location of the vacuum pump on a 240D engine. There were absolutely no other symptoms before tonight and the vacuum door locks have been disabled years ago. Thanks!

Trace the big line from your booster, you'll see the pump. There may be a fitting in the middle of that line, you can remove and check with a vac gauge to see if there is any being created.

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83 SD

84 CD

or you could just use your finger.. you should have a good ammount of suction on your finger or palm, if not then vaccume pump needs to be replaced. if its ok, then you have a massive vacuume leak.

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Have you ever noticed that anybody driving slower than you is an idiot, and anyone going faster than you is a maniac?

As long as they would add one additional commandment for you to keep thy religion to thyself.
George Carlin (Wonder where he is now..)

1981 240d (engine donor 1983 240d) recently rebuilt engine hurray! - No more.. fought a tree and the tree won.

pearl black 1983 240d 4speed (Converted!@$$%) atleast the tranny was rebuilt.

There is a check valve that screws into the top of the vacum pump. I think its about $40. They do go bad. You can rebuild your vacum pump. I think the kit is $40-60. I think a new or rebuilt vacum pump is $300. That should have the new bearings. The rebuilt kit does not have the bearings. I've only found one place with the bearings and arm for sale, $275 I think.
Tom

Pump is on the left front of the engine to the right of the power steering pump and to the left of the water pump (all directions from driver's seat). There's a large vacuum line going from the pump to the brake booster.
Your symptoms are consistent with either a bad vacuum pump or a seriously failed brake 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