Years ago when I had 'Rena' (82 W126 300SD) while doing a valve adjustment, I dropped the valvecover and broke the plastic housing (item 179) and the intermediate piece (item 71).

I had already replaced the worn EGR components (items 29, 74, 68, and 65), and was trying to source the NLA switchover valves (item 5),
before installing beefier levers (item 8) that I got from forum member Diesel Giant.
(Note: item 11 on the diagram is a listed as a screw...but in my setup it is actually a roll pin).

I decided funds would be better spent elsewhere, so I disabled the EGR system.
The vacuum connections were deleted (simple rubber vacuum connectors in place of the three-way connectors) as shown on the attached pdf, and the EGR valve got the soda can gasket delete.

I erred in leaving the components attached to the valvecover when the engine was later transferred to 'Rena 2.0' (83 W126 300SD).

The top switchover valve disintegrated and caused an intermittent binding of the throttle linkage.
It has now been eliminated from the valvecover.

Next phase is to change to non-EGR manifolds, oil catch can, and PS fender mounted 85 air filter setup.
I'll post a writeup when it is eventually done.

Attached Thumbnails

       

Attached Files

EGR delete.pdf (468.6 KB, 111 views)

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78 W116 300SD 'Desert Rose' new as of 01/26/2014
79 W116 300SD 'Stormcloud' RIP 04/11/2022

My 1984 & 85 don't have that clunky vacuum switch on the valve cover. It was replaced by a small micro-switch. I think that only affects the EGR controls since there is a separate switch under the driver's pedal to sense "full throttle request" for transmission kick-down.

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1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans

Agreed, the switchover valves normally only affect the EGR valve function...if they and their actuating levers are intact.

The switchover valves (under the black box on the valvecover) are activated by the black stepped-cam when it pushes on the actuating levers.
The cam changes position with throttle input.
The switchover valves only control the EGR valve.

My problem was that the actuating levers had been worn down, and shafts of the disconnected switchover valves were continually gouging the black stepped-cam, and acting like a brake on the throttle input...especially when gently accelerating.

The top switchover valve also failed completely.
The top internal switchover valve spring pushed the plastic piece that holds the shaft in the body of the top swithover valve out of position only at WOT and caused additional throttle linkage binding when decelerating from WOT (when the brakes were not applied).

I didn't know what was causing the notchy accelerator pedal feel when gently accelerating.
Nor did I know what was causing the sticky throttle when easing off the accelerator from a WOT position.

Only after removing the black cover did I discover the mysterious cause of my symptoms.

The upshot is that if one is disabling the EGR, the switchover valves should be removed as well...otherwise you may eventually get throttle linkage binding.

Attached Thumbnails

 

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78 W116 300SD 'Desert Rose' new as of 01/26/2014
79 W116 300SD 'Stormcloud' RIP 04/11/2022

I no longer have EGR, but still have that micro-switch. The connector plug is partly broken and falls off.

Is there any other function, or can I just unplug and relocate the wire out of the way? '85 300D but with earlier turbo engine (or at least block).

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5

a/c cut under full throttle.