I have a 1984 mercedes and it uses 5 vacuum pods to control the hvac flaps. Most of the rubber diaphragms in the vacuum pods are ripped and dont hold vacuum anymore. I am replacing all of the rubber diaphragms but using the old pod housing. I noticed when taking apart the old vacuum pods the rubber diaphragms had some sort of white chalky residue on them. I didnt think anything of it until i got the new vacuum pod diaphragms and they actually are covered in a white powder. I looked up what the white residue could be for generic rubber parts with a white residue and they say it can be mold release agent. But these new diaphragms have more than a white chalky residue you can scrape off with your finger. Its more like the new diaphragms were dipped in talcum powder and then shaken off so they are left with a fine powder all over the diaphragm. Im beginning to think this is actually there on purpose to help the diaphragm roll against itself. Because when vacuum is applied to the pod the diaphragm gets pulled down and the sides fold up over itself. Before i got the new diaphragms my idea was to clean the new rubber up and then coat it with aerospace 303 protectant but now im thinking i should just leave the white powder and not clean the diaphragms before installing them. So my question is is should i clean and coat the diaphragms in 303 or should i leave the poweder on there which is either mold release agent not cleaned off or some sort of lubricant?
Question about rubber diaphragm lubricant
- Thread starter joegreen
- Start date
I've seen similar on various parts for MB and other German cars...I would leave it. I would wager it is so the folds don't stick to themselves if they remain compressed as opposed to roll.
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CleanSump
Site Donor 2022
Second what wings&wheels said. Back in the '90s I did the pod overhaul on an '85 240D I had and wouldn't recommend putting anything on the diaphragms. The powder is just like the powder on bicycle innertubes. Keeps the rubber from sticking to itself.
Good luck. Hope your vacuum changeover valve is working.
Good luck. Hope your vacuum changeover valve is working.
I have the whole dash out now. I’m revamping all the pods and fixing any vacuum leaks and making the climate control system work 100%
Slightly off topic. Are you familiar with rollguy on the peach parts forum( probably others too) who sells kits to put sanden compressors and upgraded condensers on those cars?
JHZR2
Staff member
Yes. Ive bought stuff from him before. Haven’t done a sanden mod though. I do have a compressor that I could use for it though…
is this what you are talking about? https://klimakit.com/product/w123-sanden-sd-ac-compressor-upgrade-kit/
303 is a silicone emulsion with a little surfactant, not unlike Armor-All but not as bad as it. Talcum powder can be had on Amazon as a tube dust or billiards chalk. I’d leave the factory dust alone.
Supposedly, a prophylactic(not calling it by its actual name here) works in a pinch on Mercedes door lock vacuum actuators.
Supposedly, a prophylactic(not calling it by its actual name here) works in a pinch on Mercedes door lock vacuum actuators.
That might be his kit. I made AC hoses for him for many years.
He is a friend of mine. Lives across the Mojave river from me.
