Vacuum/Air flow diagram m103 - PeachParts Mercedes-Benz Forum

lsmalley · #1 08-26-2013, 09:02 PM

On the attached drawing this is how my current system is set up.
The air-check valve from figure 3 pulls vacuum from the top portion of figure 1 & 2. However, the EGR check valve is positioned where the air flow is in the same direction so there is never a time that my EGR valve receives any vacuum from figure 3 because the check valve is pointed in the other direction and does not allow air flow the opposite way. I turned the EGR check valve around and I gassed the throttle cable and the EGR Valve opened up but did not close so it created a sort of rough idle. I turned the check valve back the other way and gassed the throttle cable and the EGR valve did not open up. So whats going on, can someone please comment on the direction of the air flow. I was also thinking that maybe the EGR check valve is supposed to be spring loaded and reversed the other way so that when the throttle is gassed, the vacuum from figure 3 opens the EGR Valve, but then the spring closes it. Please help.

lsmalley · #2 12-24-2016, 12:00 AM

Quote:

Originally Posted by lsmalley

On the attached drawing this is how my current system is set up.
The air-check valve from figure 3 pulls vacuum from the top portion of figure 1 & 2. However, the EGR check valve is positioned where the air flow is in the same direction so there is never a time that my EGR valve receives any vacuum from figure 3 because the check valve is pointed in the other direction and does not allow air flow the opposite way. I turned the EGR check valve around and I gassed the throttle cable and the EGR Valve opened up but did not close so it created a sort of rough idle. I turned the check valve back the other way and gassed the throttle cable and the EGR valve did not open up. So whats going on, can someone please comment on the direction of the air flow? I was also thinking that maybe the EGR check valve is supposed to be spring loaded and reversed the other way so that when the throttle is gassed, the vacuum from figure 3 opens the EGR Valve, but then the spring closes it. Please help.

Anyone have an answer for this? I'm guessing that no check valve is how it is supposed to operate, but why was there a check valve there that prevented this function? In the MB literature it also shows a check valve there, but no matter which way it faces, it either never opens or it opens and never shuts.

w123fanman · #3 12-24-2016, 02:56 AM

I can't explain the function of the check valve but it would make sense that it would either keep it closed or open at all times if you have it in place. My system doesn't have it, though I am not even sure my EGR works. The vacuum to my air pump is disconnected atm.

optimusprime · #4 12-24-2016, 08:09 AM

They are all on this site .Some one show this member how to get in to the vacuum diagrams

lsmalley · #5 12-24-2016, 08:46 PM

Quote:

Originally Posted by optimusprime

They are all on this site .Some one show this member how to get in to the vacuum diagrams

I have the diagram and the FSM, but read my original post. The check valve on the line between the EGR valve and the electronic switchover valve makes absolute zero sense to me at all and logically it can not work, at least to me it can't, but maybe I'm missing something.