Originally Posted by floydla1

Hi folks,
The MB I have: '83 300SD 142K Mi Chassis W126 Engine: 617.95 Tranny: 722.3.
I have performed a full system leak test -- it holds vacuum well, about 0.2" Hg loss in ten minutes. The flaring at 2-3, which is not too bad, is occurring at ~5" Hg when acceleration is gradual. If I push the acceleration such that vacuum is less than 2" Hg, no flaring.

It appears I am missing the first orifice (#62 on the vacuum line schematic) --does anybody know what orifice size this is suppose to be? - I think you will find that this orifice is part of the " T " that branches off the main vac. line between the Vac.Pmp.-to-Brake booster chamber. Many times we find that PO(s) have drilled out this orifice so you might have to add an "in-line" orifice just after the "T" [ for you probably one of the smaller ID orifices since it looks like you are looking to lower the vacuum your Engine/Tranny-Shifter Vacuum Control system is receiving from the vacuum pump. I notice that the vacuum diagrams at PeterSchmidTransmissions.Com ONLY show the orifice sizes for the CA 1984-1985 and the Fed 1985 diesels... and these are black [0.6mm] and an unknown color that is 0.5mm

Now, if I have plugged off the EGR valve, do the 3-2 valves now have a purpose?
I think most likely there remains a function for this mechanical "switchover valve" on your 1983 diesel... that of shutting off the VCV's bleeding effect when at idle... however IF this design was merely to properly interact with the EGR's functioning, then MAYBE this is no longer needed... but my 1980 240D model has this switchover valve and I know it was NOT designed withOUT an EGR... so I think this valve probably has a function that you should retain. Check its function with your vacuum gauge and see IF I'm guessing correct on this point

Looking at the vacuum diagram, I should by-pass them as well and avoid a potential source of leaks. No?
See my response immediately above!

FYI, according to my MB dealership, the following orifices are no longer available in North America:
Red, 1.1 mm, PN 1162761029
Brown, 0.9mm PN 1162761429
White, 0.8mm PN 1162761229
I still want to try and use an adjustable orifice ( aka an 1/8-inch needle valve ) as my orifice that throttles the vacuum where it first comes off the main/large vacuum line... in other words I would purposely drill-out the " T " and add the needle valve that would allow me to easily fine-tune the vacuum level in the Engine/Tranny-Shifter Vacuum Control System!
This is my first exposure to the diesel engine -- loving it!