Remove CCU from 116 (300SD) engine shutdown issue
 

I was following a similar post but found myself hijacking it Engine won't shut off only when climate control is OFF, otherwise shuts off fine


Problem: Engine not shutting down unless Climate Control is on Defrost. Using hand-pump vacuum to CCU from engine compartment (Green tube at 4-way connector near firewall) will not hold vacuum.

Investigation: Removing CCU wood trim - remove 2 screws at bottom of wood trim just above radio (check), remove the 3 upper switches (Int rear lights, Antenna, Rear window defog), slide whole unit down and out, remove 4 screws holding wood trim to CCU. Found Green vac tube with black stripe disconnected from whatever it connects to, the CCU I assume. The black rubber vac tube connection section at the free end was a little wet with oil and the rubber is soft not able to retain vac tube. Plugging the black rubber connector with golf tee and then pulling vacuum from engine compartment holds.

OK, here is where i don't know how to proceed. Having found the problem i don't know how to remove the remaining connections to allow access to replace black rubber vac rube connection section and then reattach Green vac tube to where ever it goes.

Side note - can someone explain the thin black wires that attach to the switches (Int lights has 1, Antenna has 2, Rear window defog has 2, AC has 2). Fiber optic lights???

Chris

Everything is fairly tight and I need to disconnect additional connections to allow access to back of panel (my main problem).
OK, replaced black rubber connector piece (can't visually see T section) and still have shutdown issue in OFF mode. this might have been connected and then just slipped off during poking around.

Removed glove box as that is quick. Found another black rubber connector glistening (damn oil). Vacuum line is orange and connects to a metal device(?) Need to drop kick panel to fix but did cap off for now.

Tested system with vacuum gauge inline:
(edit) vacuum gauge inline at firewall inside engine compartment, green/black vac line (edit)
Off = 7"
Auto Lo = 7"
Auto High = 7"
Bi Level = 20"
DEF = 20"

Note: Item #38 shows "Specified leak point" so that might reflect in the measured results???

http://handbook.w116.org/Climate%5C83-604.pdf

Car will shutdown but still takes a few seconds. Pushing DEF engines stops right away. Anyone have info on vacuum levels in different stages of selection via push buttons? By the way...my A/C is disconnected (no belt, no main hoses in engine compartment).

Snapped a few shots (pictures 1 - 3) of the actuator in question (fresh air flap)?

This is right up next to the fire wall. Connected vacuum hand-pump and diaphragm moves up and down (switching from one side to the other just like the 116 door lock actuators, and holds vacuum. First picture shows the oil on bottom of actuator, behind pink vac pod.

Found another device/valve (picture 4) with vacuum splitter connection at bottom, dry (no oil) but semi-loose connection right next to center console, with kick panel removed.

Anyone have info on vacuum levels wit the different stages of CCU selections? Would like to know where i stand on leaks in the system.

Your problem is either a failed vacuum pump diaphragm or a failed shut off diaphragm. It's one of those failures that is allowing oil to get into the vacuum system. Many people put clear fuel filters in the main vacuum pump line and the brown shut off diaphragm line so that the presence of oil in the system can be easily detected.

Kerry - That is a great idea! I was just considering something similar - a clear plastic well, T'd-off main vac lines, but your idea is by far easier. I have the new style Vac Pump for the 116 - single line - so no diaphragm but understand pump is still suspect. Have tested shutoff vac control and it holds vacuum and will shutdown with direct hand-pump vac. My problem seems to be isolated in the CCU. Too bad! I do the shutoff before the CCU any day of the week. I do have a new vacuum pump ready to install but would like to figure out the existing problems before installing new, if new pump is warranted.

Now i just need to locate all the failed rubber pieces....

116 owners out there, can you slap on a vacuum gauge and give me some readouts for the different heating options; Off, Auto-Lo, Auto-Hi, Bi-Level and DEF? My readings were taken from engine compartment, T'd into CCU green line before passing through firewall.

Vacuum pods should always hold vacuum - even when activating a flap. My 85SD always runs ~ 18# measured in the engine compartment. It was around 12 until I replaced some broken pods.

A friend's 240D wasn't shutting off. A shop replaced the vacuum pump requesting $700 parts and labor but haven't been paid because it didn't fix the problem. The 240 is showing ~2# vacuum measured in the engine compartment. I expect his brake booster is leaking but we haven't had time to confirm.

That's one reason i have held off installing the new pump (parts guy will take it back as credit if not used) as it pulls 22" currently but previous test was only 18". But i am finding oil in the lines. Is the oil in the lines from an old pump or current one? Who knows.