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  #31  
Old 12-12-2009, 01:29 PM
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Originally Posted by ck42 View Post
If you haven't done this already, remove the end of the main vacuum line that connects to the pump and pull it aside so that you can look down into the external check valve. On mine, it was like the check valve was a hollow tube (all the little parts had come apart and fell inside the pump).
See if you see a little disc sitting inside there. If you're lucky/unlucky, yours will appear hollow like mine...which simply means you need a new external check valve. The unfortunate part about this is that it STILL means that you have to pull the front cover off in order to retrieve the 3-4 little parts that used to be inside the external check valve.

As for a diagram, I can't find the doc that came with the kit right now, but it did a full walk-through of the process...including which way to install the valves.
If you are talking about the big black plastic line, I have already removed that part and pulled vacuum on it with the mighty vac. I had my wife hold both ends and then I pulled vacuum on both ports (individually) on the check valve. I did not look through it. I suppose I could remove it again and take a peek?


Edit: The vacuum pump and other parts will be here this coming week. I ordered them from Phil this morning.
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1985 300D (SOLD)


Last edited by snookwhaler; 12-12-2009 at 01:42 PM.
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  #32  
Old 12-12-2009, 02:09 PM
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Not sure how it would react to pulling a vacuum if the external check valve were toast. (yes, the big black hose that makes its way to the vacuum pump)
Bottom line though, it's worth at least pointing a flashlight down inside there real quick. IF it's bad, you'll need to order a replacement so better to find out now.
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  #33  
Old 12-12-2009, 02:23 PM
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Originally Posted by ck42 View Post
Not sure how it would react to pulling a vacuum if the external check valve were toast. (yes, the big black hose that makes its way to the vacuum pump)
Bottom line though, it's worth at least pointing a flashlight down inside there real quick. IF it's bad, you'll need to order a replacement so better to find out now.
That was an easy part to pull off.... I'll check it when rebuild the pump.

Thanks again.
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  #34  
Old 12-12-2009, 05:31 PM
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Originally Posted by snookwhaler View Post
That is one of the reasons I was looking for a "picture tutorial". I was wondering about the check valves and which way they go? Is there a picture of that somewhere? Or a diagram? I can picture my self dropping them on the ground and then having no idea how to put them back in.....
There should be three check valves, two on the bottom and one on the top as the pump sits attached to the engine. The two on the bottom should have the metal "mercedes star" in, and the single one at the top should have the "star" facing out. That's the way it is depicted in the rebuild procedure (43-628 Step 16 in the manual). The center of gravity for the two bottom ones make them more likely to stay in place, while the upper one is more precariously balanced and more likely to fall out.

BTW, the picture in the manual shows a cutaway view that is upside down from the way the pump sits on the engine.
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'84 300SD 119KMi (Liesl der Diesel)
'84 300D 326KMi when the oil left (former parts car)
'82 300SD 253KMi (new parts car)
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  #35  
Old 12-12-2009, 05:51 PM
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"There should be three check valves, two on the bottom and one on the top as the pump sits attached to the engine."

doh! You're correct. I guess I was just remembering there being only 2 because the one on top was facing one way and the valve(s) at the other end were facing the other way.
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  #36  
Old 12-15-2009, 05:45 PM
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Thanks!! The kit will be here this Friday. I think it is supposed to be pouring down rain (again). I hope to have it in over the weekend with a bunch of other new stuff. I'll post my vacuum results after I get it in there.

The car has been slow to shut off a few more times over the past few days and another 400 miles.
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  #37  
Old 12-19-2009, 05:58 PM
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Ok.... I got the vacuum pump rebuild kit in there. It was a bit more of a PITA than I was expecting.

I rebuilt it "on the car". I wound up removing the PS belt, fan with shroud and upper rad. hose. Getting the front plate off the pump was easy enough. But, getting that piston out was a bit of a PITA. I had to pry it out of there with a couple of razor blades. The pump was a little oily inside and the upper check valve was all coked up.

The real frustration was putting the top check valve back in while trying to align the pump cover gasket. It was all kinked up because of the packaging. There was a little cussing involved with that procedure. But I got it in there.

The results are not what I was expecting. I'm only getting 15in. at the pump at idle. It will climb to 20-23in with some throttle but slowly go back down to 15 after a minute or so. Also, with everything hooked up the needle on the gauge bounces. So, I unhooked the brake booster and the gauge read steady at just over 15-17in. off the main line. This would rise to 20-23in. with some throttle.

The engine does seem to shut off quicker and the door lock are a bit snappier than before. But, I guess time will tell.

I also replaced #4 and #5 glow plugs today (Autolite crapola). Those 2 are difficult to reach. The PO obviously broke them when he put them in (or the indy). The nuts for the wires just spun with the shaft. Luckily my needle nose vice grips saved the day (again). But that is a different story...

Thanks to all for the advice, pointers and what to watch out for. It was a real help to "know what to expect" with the vacuum pump.
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  #38  
Old 12-19-2009, 07:46 PM
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Quote:
But, getting that piston out was a bit of a PITA. I had to pry it out of there with a couple of razor blades.
Moving the engine with the power steering belt will move the pump in and out rather quickly, and you could have jacked the piston over so it catches onto the threads of the piston rod and push it out that way.
Quote:
The real frustration was putting the top check valve back in while trying to align the pump cover gasket. It was all kinked up because of the packaging. There was a little cussing involved with that procedure. But I got it in there.
Yep, that gasket is the biggest bugger when it's deformed. But a dab of wheel bearing grease at the edge of the check valve would have held it while you mess with the gasket. The least amount necessary for it to "stick" since this is the dry side of the pump.

Good job! Now that you know your pump is good, check the rest of the vacuum system. Pull and block off each vacuum line off the main line one by one until your vacuum remains steady. If everything is blocked off and the only one left is the booster, then be prepared to replace it in the near future. If you find one of the other lines causes the jumpy gauge (most likely climate control) let us know and we'll help you isolate it.
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'84 300SD 119KMi (Liesl der Diesel)
'84 300D 326KMi when the oil left (former parts car)
'82 300SD 253KMi (new parts car)
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  #39  
Old 12-20-2009, 08:38 AM
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Originally Posted by micalk View Post
Moving the engine with the power steering belt will move the pump in and out rather quickly, and you could have jacked the piston over so it catches onto the threads of the piston rod and push it out that way.Yep, that gasket is the biggest bugger when it's deformed. But a dab of wheel bearing grease at the edge of the check valve would have held it while you mess with the gasket. The least amount necessary for it to "stick" since this is the dry side of the pump.

Good job! Now that you know your pump is good, check the rest of the vacuum system. Pull and block off each vacuum line off the main line one by one until your vacuum remains steady. If everything is blocked off and the only one left is the booster, then be prepared to replace it in the near future. If you find one of the other lines causes the jumpy gauge (most likely climate control) let us know and we'll help you isolate it.
Your piston trick would not work. I must have tried that at least 5 times. The piston kept getting caught on the threads and would start to pull back in the hole. So, I just turned the engine over until the piston was all the way out and just pryed it out of there. Thanks for the advice either way. It helped a lot!

The rest of the vacuum system is good. It is definitely the brake booster. If I run the system with the booster disconnected and plugged, the vacuum is steady and high (18+). As soon as I hook the booster up.... The gauge starts jumping around and vacuum drops.
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