vacuum issue with my 1991 Turbo Diesel 300 D 2.5
 

Well here is my problem i was wondering if you can point me out in the right direction.
I have a 1991 MB 300 Turbo Diesel i realized that the back seat head rest will not go down when i press the button and the AC blows only through the defroster not the front fins. So i started looking at the vacuum lines trying to see where are they leaking but they all seem fine (no cracks) other than some loose fittings but when i blocked those than i saw that if you suck the air out of the lines it seems like there is air still comeing from Intake Manifold Pressure Control Valve Transducer, the Orifice or Vacum Damper i cant really tell and the green line that i guess goes to the front AC fins that is also conected at the same spliter as the lines for the head rests (i have not been using some sort of vacuum device just through my lungs). Now if i connect the lines straight from the vacum pump to the headrest it will lower them but not imediatley, very late, delayed in other words like you have to keep the button pressed for 30 seconds or so to happen. I also go and try to feel how much vacuum does the pump creates and is really weak in my opinion. So i was wondering a good working vacum pump how much vacum does it create?? is it noticable like will it hold the finger or toungue if you place it at the pump outlet directly :) or is it barely noticable but it builds up if there is no leak and than all those above components are foulty.
Any help will be appreciated it.
Thank you very much
Denis

Hello Denis,
Get your self a mighty Vac and go hunting....
Sorry cant be more specific...
But here's the VAC Diagram....

And here I thought the rear headrests used vacuum from the central locking pump, not the engine vacuum pump. I'm gonna have to look into that...

Sixto
87 300D

Yep, the vacuum for the rear headrests is taken from the engine. After the vacuum bleeds off when the car's off the rear headrests will not retract.

Can someone of you guys, who have been so helpfull with all this readings that i am doing, tell me where can i order a Intake Manifold Pressure Control Valve Transducer or Y31/2 from the pics. What is the part number for that valve and cost and where can i find one. I followed all my vacum lines one by one and there are two leaks now left one comes from that and the other comes from the Orifice next to the Vacum Control Valve

Thank you Denis

All three transducers on this car are the same thing and are interchangeable. EPC says the old part number (001 540 79 97) has been replaced by 000 545 03 27.

on this diagram what is number 20 and 21 the one line comeing from the vacum pump that goes to 20 (orrifice) if you introduce vacuum it leaks what does that do with the 21 coming out of it. it seems like they are all part of 22. what is the purpose of all that arethey all conected and where does 21 go????
any help will be appreciated i went to mercedes dealer and spend two hours trying to find and order that part and they could not find it
thank you
Denis

the leaking vacum line is 61a. when i disconnect that line at the vacuum pump and introduce vacuum to it through a manual vacuum pump there is no holding at all. is that something that can be replaced. and why does it show two lines coming from it? mine only has that one only vacuum pump to 61a and no other one split and going to number 123 the vacuum amplifier? I have not removed 72 the damper and the line from it do you think that might be the problem? where is 123 the vacuum amplifier located at in the actual car? are they all part of 65 the vacuum control valve or can they be replaced separately??
thank you a million times

oh and to explain again what we have been talking through e-mail. i was wondering if it could be done anything without reprecussions and errors by coneccting the line from the vacuum pump 61d to the filter 62a directly and the vacuum reservoir 179 and leave that whole other part of 61d out with all the transducers and splits. do you think that can be done or not really
thank you
denis

ok will do. i have a 1991 300 D 2.5 Turbo 124 body 602 engine so yeah we are on the right track.

Does your private messaging system work?

yes it does

ok for the time being i found a free transducer that seems like it works but is not exactly like mine i think is the replacement of the one i have in my car and fited to the car it hold 14 hg of vacum and it does retract the flap on the right side of the turbo parallel with the egr valve ( i cant see if egr is doing anything) so i know it works. how do i know that the egr is working etc. or better ask (since i could care less if egr is working or not) how do i know that the boost is working properly coming from EDS? plus i putt silicon around that vacuum control valve as that guy at the benz dealership said but i don;t know how much vacuum it should hold since i think its holding some now? also another question do you know of any procedures on how to align head lights since i switched mine to euro or a thread to point me to.

thank you

denis