Rebuilding these older W123 vacuum pumps is a walk in the park. I've done this job twice, once on a '79 300TD, once on an '80 240D. BTW, there is no piston, it is a diaphragm style pump. The usual failure is a torn diaphragm. The parts are dirt cheap. The only tricky part is keeping the return spring compressed during assembly. If you want to see my setup for doing that without building a jig, email me for a pic.
Greg -----Original Message----- From: mercedes-boun...@okiebenz.com [mailto:mercedes-boun...@okiebenz.com] On Behalf Of John Reames Sent: Friday, May 28, 2010 6:02 PM To: Mercedes Discussion List Subject: Re: [MBZ] 83 240D Manual shifting problems almost leaves me stranded I had one do that to me; until the brakes totally failed, I had no idea what was going on. The master cylinder did not lose fluid that I could tell, and the mechanic that did the safety inspection did not catch it. When I pulled off the master cylinder, brake fluid ran out of the booster. it must have had fluid up to the middle of it's mounting hole... About 10k miles later the vacuum pump failed (the PO indicated that it was the second pump that he put on it). When I put a new pump on it, many vacuum issues sorted themselves out; the old pump bad been weak for some time. Speaking of which, I have the old pump still, I would expect that with new valves (including the one in the fitting) and maybe resealing the piston, that it would be servicable. I'll check it out, and if the arm and bearing look ok then I might rebuild it... Pull the master cylinder. Look in the brake booster. It can and will fill with brake fluid which can be sucked through the vacuum pump, where it has a jolly good time softening the seals and check valves during its brief stop on the way to mingle with your engine oil... -- John W Reames jwrea...@comcast.net Home: +14106646986 Mobile: +14437915905 On May 28, 2010, at 12:44, Zoltan Finks <mmmmmsuchpo...@gmail.com> wrote: > Okay, I must admit I have been humbled on both the mechanical and > driving > fronts. (though I never claimed to know much about fixing cars) > > I should have thought to play around with rpms and speed as I was > fighting > to shift the thing. Especially since I when I used to have my > motorcycle, > every once in a while I would have an effortless, silent shift. Back > then, I > surmised that I must be going just the right speed when I shifted, > and had > the right engine speed, and probably was on just the right amount of > incline > or decline or flat. I will now not consider myself a good manual > shifter > until I master this clutchless shifting you all speak of. Actually, > I never > did ever hit one of those awesome "speed shifts" that my brother > used to > pull off in his 340 Duster, so I pretty much knew I was not a stud. > My hot > rod had an auto. All us auto guys always had stick envy. > > As for the undriveable 240: To date I had had no problems with > shifting > system, so I found myself yesterday searching under the hood for a > clutch > cylinder. The owner's manual didn't provide much help. > > So there is a cylinder above the clutch pedal, and one at the > transmission? > Ok. I'll check for leaks. > > I do know that there has always been seeping below the brake master > cylinder, but the fluid level does not go down noticeably. > > I can also say that the hose leading from the brake master cylinder > and into > the firewall is braided (not steel braided) and has a hose clamp. I > wondered > if the hose clamp setup was not stock. > > These are just observations from yesterday on the fly. > > Brian > > On Thu, May 27, 2010 at 6:53 PM, OK Don <okd...@gmail.com> wrote: > >> You can shift it when the clutch is acting up - just pretend that >> you don't >> have a clutch at all. You need to rev the engine to match the speed >> it >> needs >> for the gear you're down shifting into. Or rev it too much while in >> neutral, >> then the gear will slip in when the speeds match with a little >> pressure on >> the shifter. >> I think all manual tranny drivers shoulod learn how to drive >> without a >> clutch -- as I did the first time the clutch cable broke in my VW! >> >> On Thu, May 27, 2010 at 8:26 PM, David Bruckmann < >> bruckma...@transcontinental.ca> wrote: >> >>> Probably leaking clutch master or (more likely) slave cylinder. >>> >>> The clutch is fed from the rear half of the brake fluid reservoir. >>> It is >>> filled, however, by overflowing from the front half. The clever >>> designers >>> also put the take-off point for the clutch master cyl halfway up the >>> reservoir (in case all you automatic-types were wondering what that >> dead-end >>> take-off is halfway up your brake res) so that it is less likely >>> to cause >>> lack of fluid at the rear brakes. >>> >>> If topping up solves it, you have a leak. >>> >>> Fortunately it's not a very difficult job, or at least it wasn't >>> on my >>> W115, which has the same transmission IIRC. >>> >>> D. >>> >>> >>> At 1:05 AM +0000 5/28/10, mercedes-requ...@okiebenz.com wrote: >>>> Message: 15 >>>> Date: Thu, 27 May 2010 18:05:00 -0700 >>>> From: Zoltan Finks <mmmmmsuchpo...@gmail.com> >>>> To: Mercedes Discussion List <mercedes@okiebenz.com> >>>> Subject: [MBZ] 83 240D Manual shifting problems almost leaves me >>>> stranded >>>> Message-ID: >>>> <aanlktinf0v1d8crnkl-hzri69aope7x5rdijvwbte...@mail.gmail.com> >>>> Content-Type: text/plain; charset=ISO-8859-1 >>>> >>>> Hello old list friends, >>>> >>>> A problem to ask about today: >>>> >>>> 83 240D manual shift. Started having problems downshifting. >>>> Didn't want >> to >>>> go into 2nd after being in 3rd. Didn't want to go into 1st after >>>> being >> in >>>> 2nd. >>>> >>>> Basically began to feel like I was trying to shift without the >>>> clutch. >> As >>>> much as it pained me to horse on my beloved automobile, I was >>>> forced to >>>> either pull over and get a tow or force the thing into the gears. >>>> >>>> Dawned on me that the clutch was basically engaging later, or less >>>> effectively in the pedal stroke, if that makes sense. >>>> >>>> I added some brake fluid to the reservoir and it temporarily >>>> solved the >>>> problem. It was not that low at all, but the added fluid made >>>> problem go >>>> away. >>>> >>>> But later, problem reappeared, even though the fluid is still >>>> topped >> off. >>>> >>>> My guess is that the tranny is this sensitive to being slightly >>>> low on >>>> clutch fluid because the clutch disk needs replacing? >>>> >>>> Thoughts? >>>> >>>> Thanks, >>>> Brian >>> >> >> -- >> OK Don >> Panic! 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