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  #1  
Old 08-10-2009, 09:26 PM
Richard Howard
 
Join Date: Nov 2008
Location: Western NC Mountains
Posts: 69
W126 - ACC Vacuum Pod R&R - Special Tool?

I've started work replacing the rubber diaphragms (George Murphy has them - (865) 482-9175, internet: perfanalysis@comcast.net) in the vacuum pods for the climate control system and have run into a problem when trying to replace the pod for the diverter flap. This is the one above and to the right of the throttle pedal, behind the carpet panel on the driver's side of the transmission tunnel.

The area is cramped and I'm not able to grip the pod tightly enough to turn it to get the three tabs to lock the pod back into its bracket.

Question: Is there a special socket that fits onto the bottom of the pod (with the vacuum line removed) that allows it to be turned and latched onto the bracket? Or some kind of strap wrench that will grip the pod?

Also, concerning the two pods above and behind the glove/map pocket that have two diaphragms and two vacuum lines to each, has anyone found it impossible to remove the bottom diaphragm from the center piston assembly in the mid-section? There is a black plastic cap that fits inside the center of the bottom diaphragm that's held tight against the center piston assembly. So it seems that the bottom diaphragm in these two pods cannot be replaced - only the top one can be changed?

My W126 is a 1982 diesel - maybe these were built with these partially unrepairable dual diaphragm pods?

For now I've got the levers moved by these pods taped in position to give the airflow I want and the vacuum lines capped.

Any comments, lessons learned, or secrets about repair of these pods will be appreciated.

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1982 300SD W126.120 with an OM617.950 from a W116.120
1984 300SD W126.120 with an OM617.951
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  #2  
Old 08-10-2009, 10:01 PM
tyl604's Avatar
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Join Date: Feb 2008
Location: Atlanta, GA
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As I remember there was a post in the last six months that said that there were two types of pods - single and double diaphragm. One could be repaired and one could not; but for the life of me I cannot remember which was which. You can probably find it in a search for "diaphragm."
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Old 08-10-2009, 10:24 PM
sixto's Avatar
smoke gets in your eyes
 
Join Date: Jun 2000
Location: SF Bay Area
Posts: 20,802
IIRC, for the double diaphragm pod you have to cut away the old inner diaphragm then slip the replacement inner diaphragm (with a hole) into place and then fit the outer diaphragm. George gives instructions to do this.

I didn't have luck rebuilding double diaphragm pods. The replacement rubber is less pliant than the original rubber and the vacuum system in my SDL couldn't pull the pods completely shut. Better than nothing but there's a stretch of I-5 through a cattle ranch near Coalinga CA that requires the cabin to be hermetically sealed

Sixto
87 300D
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  #4  
Old 08-12-2009, 02:42 AM
Johnson Chan's Avatar
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Join Date: Aug 2003
Posts: 229
Special tool needed: a female with small hands. Do you have a wife, g/f, neighbor, etc. to help you?

The dual pods are the ones that are troublesome to rebuild.

Do a search, I cant remember the guys name, but HE SAID, the vacuum pod rebuild diaphrams was a little different than the ones he was replacing OE. Even with the new diaphrams, when compressed, the rod does not move the full length of travel. In other words, your vents wont open all the way with the rebuild kits.

This is just what THAT guy said, not from my expereience. Personally, I bought all new pods from the dealer. This way if it does fail within a year, THEY have to take everything apart and replace it for free under their warranty program.
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Old 08-12-2009, 08:18 AM
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Location: Middle TN
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"Personally, I bought all new pods from the dealer. This way if it does fail within a year, THEY have to take everything apart and replace it for free under their warranty program. "

How much were the pods?
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  #6  
Old 08-23-2009, 11:15 AM
Johnson Chan's Avatar
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Join Date: Aug 2003
Posts: 229
Junkman,

Not much. The center pod was $21 and ECO recirculation pod $51. Keep in mind I have a wholesale account with the MB dealer too. So retail is going to be higher.

I figure for the center pod, $21 brand new and a 1 year warranty, I cant go wrong. If it fails, they can take it call back apart.
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  #7  
Old 08-23-2009, 11:43 AM
Banned
 
Join Date: May 2002
Location: Blue Point, NY
Posts: 25,396
Quote:
Originally Posted by Richard Howard View Post
Also, concerning the two pods above and behind the glove/map pocket that have two diaphragms and two vacuum lines to each, has anyone found it impossible to remove the bottom diaphragm from the center piston assembly in the mid-section? There is a black plastic cap that fits inside the center of the bottom diaphragm that's held tight against the center piston assembly. So it seems that the bottom diaphragm in these two pods cannot be replaced - only the top one can be changed?
Despite any and all claims to the contrary, you CANNOT rebuild the dual diaphragm pods and have them work correctly when you are finished. They require replacement. The design of the rear diaphragm doesn't allow a replacement........only an "addition".........and it will not provide the proper stroke.

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