Vacuum Pump problems on 603.97 Engine
 

What typically happens when or if a vacuum pump goes bad on one of the 3.5 engines ?
And what does the pump do in relation to proper engine function ? Honestly don't know, but curious.

From what I have read around the forums is your brakes wont work that well, anything thats vac operated likely wont work, your transmission may not Shift right etc.

These 60X rarely fail operationally, i.e. they internally fail and as a result no longer generate vacuum.

With a catastrophic mechanical failure; parts of the vacuum pump's actuating lever, roller, and/or roller’s bearing which reside in the timing chain chase fall down into the timing chain crankshaft sprocket area! Usually when that happens at minimum the timing chain breaks. Most of the time if that occurs at speed without the chain, the valve train is thrown out of synchronization with the crank and pistons will eventually collide with the now un-synchronized valves bending them, usually the hardened cam shaft is broken in numerous places as a result of this interaction!

Vacuum Pump
 

That does not sound good . Should the pump be pulled and checked for internal problems at some point in time ? I would hate to have one come apart and wipe out an engine .
I was looking at a very rough 87 SDL locally, had 300K on it. It sounded like a worn Deere, have never heard a diesel that noisy . Made enough strange noises that I could not pinpoint anything;did not persue buying it as it looked like trouble .
Thanks for info .

Hm. this just happened to me on jan the 1st. the symptoms were that everything vacuum-operated stopped working. My tranny started shifting rough and making a clunk noise when slowing the car down to a stop. My brakes suddenly required a lot of pressure to be able to stop the car, and when I got home after this ordeal i wasn't able to shut down the engine with the ignition key; I had to pop the hood open and push the little stop lever that Mercedes engineers put there for such an instance. I disconnected the main line going to the brake booster and there was zero vacuum, which tells me that the pump just failed. Now I face 2 options: replace the pump or get a repair kit and work on it. The pump is not cheap. New costs around $400 to $500, the kit can cost as low as $60 to as much as $150, depending on the website. General autoparts stores DO NOT carry these parts so don't even bother to go to you local autozone, unless you enjoy them guys checking their systems and telling you with a puzzled look that they have no clue how to get such a part. The pump is located below the steering pump, more or less, and I read that is better accessible if you take the radiator off. it does look like it has a lot of screws that would be pretty hard to reach if you don't get the radiator off. I haven't gotten into the repairing stage just yet, but I should be able to post something about it as soon as I get the parts and am done with it.