E-Class (W123) 1976-1986: 240D, 280E, 300D, 300TD, 300CD

Vacuum prob

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Old Apr 22, 2011 | 12:08 AM
  #1  
CanadaKevin's Avatar
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1982 300td, 1981 Honda XL500
Unhappy Vacuum prob

Hey guys, new to this forum, 2 weeks ago i got a 1982 mercedes 300td turbo diesel wagon. the problem is that there is no vacuum. when you turn the key off it keeps on running, i have to go under the hood and press the stop button. I know the vacuum pump[ needs a rebuild because there are no power brakes and i took the main vacuum suply line going to the brake booster and got nothing...so my question it: What is the easiest way of doing a vacuum pump rebuild? i tried to stick my hand in there but there is no space. i got the rebulid kit. anyone got specific step by step instructions for me? Thanks in advance
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Old Apr 22, 2011 | 02:54 PM
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83, 300D Federal
Depending on your ability to shop around for a good price in general rebuilding the Vacuum Pump costs more than getting a new one.
(There is actually 2 rebuild kits. One kit rebuilds the Piston/Valves and the other replaces the Arm assembly that drives the Piston.)

Also, when done with your rebuild you have no warranty.

Right under where the Main Vacuum Line attaches to the Vacuum Pump is a Check Valve that can be unscrewed. Often that Check Valve is the source of a Vacuum Loss.

Remove the Check Valve and spray out the inside with WD-40 and see if the parts inside are still intact (they break after long use).
If you are lucky like I was just cleaning the Check Valve will restore Vacuum.

A new Check Valve Can cost as much as $60 but if you need one shop around.

If you buy a new Vacuum Pump it will come with a new Check Valve.
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Old Apr 22, 2011 | 04:36 PM
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1982 300td, 1981 Honda XL500
today i was messing around wth the alda and broke the screw out. i have a parts car, so i will most likely get the whole alda off of it. any suggestions?
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Old Apr 24, 2011 | 08:05 PM
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1982 300td, 1981 Honda XL500
ok so i got the alda fixed, took the old one off and put the working one of the parts car and installed it, turned it up and now runs better than new. tomorrow i will be taking the check valve off and cleaning it out. hopefully it will fix the vacuum since i really dont wanna take the whole vacuum pump off to do a rebuild. thanks for the reply and happy easter!
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