G'mornin',

I began a thread a few weeks ago...search Shorebilly.....and I went thru my vacuum problem on my '85 300D-T, Federal,.....eventually I found my problem to be the "Switchover Valve" that supplies Vacuum to the Boost Dump to be leaking.....

The thread that I began has some highlighted photos and such.....

....it was leaking through the valve to the "Vent to Passenger Compartment"

There are 2 devices.....

1) Vacuum Converter.....this device has a nest of Vacuum plumbing, but basically it supplies Vacuum to the EGR Valve, to open it, and vents that vacuum back to atmosphere, to close it.

2) Switchover Valve.....this device has 3 connections, Vacuum from Supply, Vacuum to "Boost Dump", and Vent to Atmosphere (via the li'l filter , to Passenger Compartment)......

if either of these devices stick, hang up, or otherwise leak "internally" they can/will connect your "Vent" directly to your "Vacuum Source/Supply"

Read my thread.....

I have eliminated the "Vacuum Source/Supply" from both of these devices.....initially I plugged the Vacuum lines with Golf Tees......since, I have removed all of the related vacuum hoses/lines......and replaced the 4 way vacuum connector that supplies vacuum to the switchover Valve with a 3 way connector (taking the Switchover valve out of the vacuum circuit entirely) and replaced the 3 way vacuum connector with a 2 way (small piece of hose) connector (taking the Vacuum Converter out of the Vacuum circuit).......I have left the both devices mounted to the wheel well, for the time being.....because...I do not know what removal of the electrical component (solenoid coils) will do to the operation of the "Control Unit" which also outputs to the tachometer and a couple of other EGR/Pollution control items`.......

Note: I saved the whole "Vacuum Tubing Assembly" (sort of like a wiring harness) that connects both of these devices to both vacuum and vent.....just in case I decide to replace/renew the switchover valve that began my odessy thru the Vacuum System.........

Note II: this all began because I changed the "EGR Filter".......the old one was plugged solid.......

Luck to ya....send me a personal message if you have any questions, I will do my best to help you...

SB

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Diesels:
'85 300D, "Max, Blue Benz", 155K, 27.0 MPG
'84 190D 2.2, "Eva, Brown Benz", 142K, 40.2 MPG
'77 240D (parts car)
'67 Eicher ES 202 Tractor "Otto" (2cyl, Air Cooled, 30HP)
Gassers:
'94 Ford F-150, "Henry", 170K (300 Six) 17.5 MPG
'85 190E 2.3, 148K....Parts Car
'58 Dodge W300M Powerwagon (Flat Fenders) Less than 10 MPG