Re: [Chrysler300] RE: Leaky Vacuum Actuators-1964 300K
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Re: [Chrysler300] RE: Leaky Vacuum Actuators-1964 300K

I have had good results on grommets with a wooden toothpick , possibly blunted a bit on end to avoid digging in and sort of push on lip and work your way around 360 . I imagine one side of a very small Kelly clamp would work too , and has a blunt smooth end . Then use tooth pick to get a ring of ws cement around by turning grommet , grease on rod really helps , seals and lubes, silicone only , as oils destroy rubber . The grommet got out probably by being stuck on rod? They are pretty strong . About 3 sq in at 14 lbs vacuum is like 40 lbs . 

Sent from my iPhone

On Apr 25, 2017, at 1:30 AM, 'Rich Barber' c300@xxxxxxx [Chrysler300] <Chrysler300-noreply@xxxxxxxxxxxxxxx> wrote:

OK.  I removed actuator #4 (Recirc. and Fresh Air doors are mechanically linked) and found it had its grommet pulled out.  Not a very complicated grommet and still undamaged soft black rubber.  The inner hole appears to have ribs to assure a seal that allows sliding while minimizing leakage around the 3/16” rod.  So, the answer to question 4 is no.   The Recirc and  


Now I need advice on technique to get the 0.6” OD lower flange of the grommet back through the 0.4” hole in the can.  If I can find out how to do this, I will remove the other leaky grommets so I can clean and polish the areas of the cans around the grommet-hole.  I’m reluctant to pop them out unless I can be confident I can re-insert the grommets without damaging their sealing surfaces.  This is essentially question 6.


Recommendations to polish and lube the rod and use weatherstrip cement to seal any grommet leaks were appreciated.  I was not encouraged to attempt disassembly and patching. 


All tech tips welcomed.


Rich Barber

Brentwood, CA


From: Rich Barber [mailto:c300@xxxxxxx]
Sent: Sunday, April 23, 2017 9:53 PM
To: Chrysler 300 Club Int. Server <chrysler300@xxxxxxxxxxxxxxx>
Subject: Leaky Vacuum Actuators-1964 300K


I need a little experienced advice on servicing vacuum actuators as installed on ’60-’65 Chryslers.  So far, I have the heater bypass actuator out and determined to have a leak across the diaphragm and the damper/main actuator and deflector actuator leaking around the OD of the grommets that seal the rods to the cans.  The main and deflector actuators do not leak across the diaphragm.  All three actuators still work but present constant vacuum leaks that I hope to correct.



  1. Is it feasible to disassemble the metal can, access the diaphragm, patch it and reseal it?  I viewed a video on line by a guy that did that for an old T-Bird.  He patched the leaky diaphragm with a tire patch!
  2. Does anyone rebuild these commercially?
  3. Does anyone have a used and functional heater bypass actuator they would part with (this is the actuator mounted under the hood)?
  4. Is the grommet just that or is it part of the internal diaphragm?
  5. Are new grommets available?
  6. If available, can leaky grommets be replaced without disassembling the can?
  7. What would be a good material to use to seal the OD of the existing grommet?  JB-Weld?  Windshield gasket sealer?  Other?  All the cans have light surface rust and cleaning around the edge did not stop the leak.
  8. I had to pop off two little snap rivet connectors on a plastic shield covering the main rod end connection in order to remove the damper actuator.  Anyone know if the tiny plates just snap back on to the rivets?  Very difficult to access the end connection without popping off the little plastic cover.


BTW, the ’65 Service Manual has better pictures of and instructions for this heater-A/C unit and the ’65 Parts Catalog has better descriptions and nomenclature for each of the four actuators.  The ’62, ’63, ’64 & ’65 Parts Catalogs all show the same part numbers for these four actuators.


Back to the garage tomorrow to check out the fourth actuator.   I’m learning more than I want to know about the plumbing, linkage and wiring behind the 1964 300K dashboard.


Rich Barber

Brentwood, CA


Posted by: John Grady <jkg@xxxxxxxxxxxxxxxxx>

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