Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help



Go Back   PeachParts Mercedes-Benz Forum > Mercedes-Benz Tech Information and Support > Diesel Discussion

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 11-07-2002, 09:52 AM
Registered User
 
Join Date: Sep 2001
Location: Concord, MA
Posts: 603
vacuum element for center nozzle

I found the leaky component of my vacuum system (85 300D)...of course it is the most difficult one to replace. Has anyone replaced the center nozzle vacuum element... the pink and white thing with the rubber diaphram in it way up under the dash just behind the center nozzles.

I can see it and touch it, but I dont know if I can manipulate the thing during replacement without removing the dash.

Thanks,
Mark

__________________
1984 300TD Wagon, 407,800 mi (current daily driver)
1985 300DT Sedan, 330,000 mi (gone to that great autobahn in the sky)
Reply With Quote
  #2  
Old 11-07-2002, 10:08 AM
Registered User
 
Join Date: Jan 2002
Posts: 18,350
I asked George Murphy this question. He supplies the rebuild kit for the modules. He said no. Somewhere in this forum is a message that indicates someone once did it but it required breaking a component and leaving it broken. There were no detailed instructins.
If you have the nozzles that can be opened and closed at the dash, (my 85 does, my 77 does not) there is an alternative solution. Plug the vacuum line to the module with a BB. Reach up under the dash through the glove box and pull off the flexible rubber cover on the vents and insert something in the vents to keep the flaps open. A piece of aluminum stock bent to hook over the edge of the duct will work. The flexible rubber can then be installed on top of it. Then control the flow of air out of the vents with the manual nozzles.
In my view, this is actually a better fix than replacing the vacuum servo module because it turns that feature of the climate control system into a manual system and you won't have to worry about that vacuum component anymore.
__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13
Reply With Quote
  #3  
Old 11-07-2002, 10:39 AM
NIC
Guest
 
Posts: n/a
Well Kerry, I'm definately gonna follow your advice. About the only feature on my car I really dislike is the HVAC control system. My center vents have not worked for two years....was waiting to fix when I found a better dash to install in place of mine.

Thanks for tip.

Nic
'85 300CD
Reply With Quote
  #4  
Old 11-07-2002, 01:29 PM
Registered User
 
Join Date: Jan 2002
Posts: 18,350
I'm curious. Now that you have done it by removing the dash, can you imagine a way it can be done through the opening of the glovebox? What parts of the process would be difficult or impossible.
__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13
Reply With Quote
  #5  
Old 11-07-2002, 02:10 PM
Registered User
 
Join Date: Jan 2002
Posts: 18,350
I did look at the picture but I only have the CD manual and it's really hard to know exactly what was there. I was thinking that perhaps some of the difficult connections could be cut with a dremel tool and replaced with something else.
__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13
Reply With Quote
  #6  
Old 11-07-2002, 02:41 PM
lrg lrg is offline
Registered User
 
Join Date: Jul 2001
Location: San Francisco
Posts: 1,163
It definitely is possible to replace the element without removing the dash, I have done it on my W123. It's not easy and it helps to have small hands. You'll need to remove the glovebox and the two eyeball canter vents. I was able to remove the acuator by using needle nose pliers to break off the plastic pins that hold the unit to tha bracket. It's not hard, after 15+ years mine were pretty brittle. Also, the press on fastners bill bend off if you squeese them hard enough. The unit comes out easily through the glovebox opening (note how the hoses are attached and routed before you pull it out). The diaphram inside mine was split. The tricky part is getting the new unit attached to the bracket. There is a large rubber vent connector that attaches at the back of the center vents that you'll need to unattach at the dash end. Mine was just slip fit over the back end of the vents. When you push that out of the way you can get pliers and/or a couple of wrench extensions through the vent openings and behind the acuator to hold it in place while you press on the fasteners. If you are doing this alone (which I did) you'll need to contort yourself a bit because you'll have your left hand trying to hold the unit and your right arm up to the elbow in the glovebox opening to press on the fasteners. I found if I used little bits of tape to hold the fasteners to my needle nose I could just get them on. I also bought a couple extra in case I dropped them behind the dash. I was able to snug the fasteners up pretty well but probably not as completely as if I took the dash off....it's hard to get the leverage you need so you'll have to experiment a bit to get them on all the way. Once that's done you'll need to reattach the rubber vent connector to the back of the vents again. I again did the one arm inside and one arm outside routine and was able to get it back on. Lastly plan on replacing the foam tube around the temp sensor that runs above the glove bacx because you will break it up for sure with all the messing around in there.I did this repair over two years ago and it has worked perfectly since.
__________________
LRG
1987 300D Turbo 175K
2006 Toyota Prius, efficent but no soul
1985 300 TDT(130K miles of trouble free motoring)now sold
Reply With Quote
  #7  
Old 11-07-2002, 02:51 PM
Registered User
 
Join Date: Jun 2000
Location: Plano, TX
Posts: 2,551
I did this repair back when I owned a 123. The center vent actuator is always the first to go - it's out front right under the dash where it gets more heat from the sun than any of the others. I'd characterize the repair as more tedious than difficult. There's no rocket science involved - just follow the instructions in the manual to disassemble everything. I didn't completely remove the dash from the car - just getting it to where it could be pulled out of place several inches was enough. Think it took about 4 easy hours - I work pretty darn slow.

- Jim
Reply With Quote
  #8  
Old 11-07-2002, 03:12 PM
gsxr's Avatar
Unbanned...?
 
Join Date: Aug 2001
Location: USA
Posts: 8,063
I recommend pulling the dash, and repairing/replacing ALL of the pods. George's kits are cheap and a whole new element still isn't that pricey. Do the job once, do it properly, and you will never need to worry about it again (ok, at least for another 10+ years.) Figure $30-$40 to repair, or ~$100 tops to replace everything.

That said, I have looked at mine and don't know how anyone - even with little hands - could do it with the dash in place. My hat's off to LRG for managing this feat. I've done this job on two W124's, the second time it only took me 5 hours start to finish, and that was replacing ALL of them. I posted detailed instructions on this forum about a year ago. I need to do my other 124 (probably in a few weeks), and also need to do my 123. I'll be timing the project and taking photos too.

For either, I wouldn't attempt it without the factory manual in hand. On the 124 I found a few shortcuts - steps that could be eliminated from the factory procedure (i.e., you don't need to pull the heater core like it says you do.) Hopefully I can speed up the 123 process as well. It will be nice to have fully operational ACC once again...! Like Jim said, it's not that difficult, just tedious.


Regards,
__________________
Dave
Boise, ID

Check out my website photos, documents, and movies!
Reply With Quote
  #9  
Old 11-07-2002, 03:21 PM
lrg lrg is offline
Registered User
 
Join Date: Jul 2001
Location: San Francisco
Posts: 1,163
Did I mention that it two weeks for my skinned knuckles to heal?
__________________
LRG
1987 300D Turbo 175K
2006 Toyota Prius, efficent but no soul
1985 300 TDT(130K miles of trouble free motoring)now sold
Reply With Quote
  #10  
Old 11-07-2002, 05:34 PM
The Bob
Guest
 
Posts: n/a
Hey folks,

I might have been the guy refered to before about reassembling the vacuum unit where it sits up there in the center dash. Basically I replaced the rubber vacuum piece only. So if you can buy just that it would be alot cheaper. The hard plastic casing does not fail I wouldnt think.. If interested do a search on a previous post for more detailed info.

I did it a while ago so I dont remember all the specifics but I did practice the reassembly outside the car to get the hang of it. with gentle vacuum from your mouth using about2 feet of vacuum line you can maintian the position of the the rubber diaphram while putting the vauvuum element back together.

I remember the job only took about 45 minutes and I got it together the first time.

For once I did something good.

bob c.
Reply With Quote
  #11  
Old 11-08-2002, 06:54 AM
Admiral-Third World Fleet
 
Join Date: Feb 2002
Location: Central FL
Posts: 3,069
Yes, I have done it pretty much the way Irg described it, hands through the center vents and glove box opening. It can be done and it is painful. Has to beat taking the dash off , though
__________________
80 300SD (129k mi) 82 240D stick (193k mi)77 240D auto - stick to be (153k mi) 85 380SL (145k mi) 89 BMW 535i 82 Diesel Rabbit Pickup (374k mi) 91 Jetta IDI Diesel (155k mi) 81 VW Rabbit Convertible Diesel 70 Triumph Spitfire Mk III (63kmi)66 Triumph TR4a IRS (90k mi)67 Ford F-100 (??)
Reply With Quote
  #12  
Old 11-08-2002, 09:02 AM
NIC
Guest
 
Posts: n/a
This was/is an interesting and practical discussion.

After reading all posts, I still think for me, the best approach is to just manually use the center vent controls and disconnect that vacuum element. I don't have small hands and don't have a manual. So unless someone knows that doing what Kerry suggests (bypass the element) will somehow mess something up, I'm going that route.

When I do get a new/better dash (dealer has new ones for the....gasp...low price of about $700 so if anyone has a black one in good condition I'm in the market), I'll go to the trouble of finding out how to remove the old dash and then repair all of the elements before installing the new dash.

Thanks all for input. This is exactly why I like this web site.

Nic
Reply With Quote
  #13  
Old 11-08-2002, 09:53 AM
Registered User
 
Join Date: Jan 2002
Posts: 18,350
The repair I described earlier does not seem to have any bad side effects. I did it about a month ago and everything is working fine.
I do however, have questions of those who replaced a failed diaphragm. It looks to me as if the vacuum modules come in two halfs joined by three little arms that snap into place. Am I correct in thinking that if you took the module apart while still in place, the diaphragm can be replaced without completly disconnecting the module from the flaps it operates? Or, is it necessary to actually disconnect the actuating rod in order to replace that diaphragm. I think that disconnecting those three arms by feel under the dash should not be all that difficult.

NIC:
Have you considered one of the hard plastic dash covers sold by Performance for about $110? Seems like a much cheaper and easier fix than replacing the whole dash.
__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13
Reply With Quote
  #14  
Old 11-08-2002, 11:37 AM
NIC
Guest
 
Posts: n/a
Kerry, I did consider the overlay option as I understand that they work quite well but....they are not the same as a regular dash and I will probably go for the gold on this one. I'm a little obsessive about my car (I don't think I'm the only one!) so can't compromise much.

Nic
Reply With Quote
  #15  
Old 11-10-2002, 10:20 PM
rob_frick
Guest
 
Posts: n/a
Cool My turn !

After reading all of this banter today I decided to tackle this job myself. I will have to say that it is not that bad of a job.
Also there is some benefits of being able to access other components while the dash is open. I found that the most difficult task was re-seating the dash in the correct position, especially at the windshield. There is a lip that needs to be below the windshield seal. I took two pics while the dash was off. The vacuum pod for the center vents is the pink one. I had once to though that it might be possible to replace it without the dash removal, but now I think that it the only way to go. Also I am not sure how difficult it would be to release the damper actuator arm from the damper. (see the Dash-2 pic) As for being able to replace just the diaphragm, I donít think itís possible to release the catches without having access to all sides if the pod. At any rate, now mine are done, and I wont really mind doing it again if required.
Robert
Ps See you guys next Saturday !
http://home.attbi.com/~frickfamily/Dash-1.jpg
http://home.attbi.com/~frickfamily/Dash-2.jpg

Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On




All times are GMT -4. The time now is 05:55 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2021, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2018 Pelican Parts, LLC - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page