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 08-30-2006, 09:45 PM
80300dbenz's Avatar
Registered User
 
Join Date: Mar 2006
Location: Houston
Posts: 125
door lock vac line test

On my 1980 300D the door locks stoped working and i decided to test all the lines on the driver side floor and fron pass. side floor. One red and green line goes across to the fron passenger side floor and when i was testing those it wouldnt hold vac. All the others did except for the one going to the trunk element to i took it out and blocked it. It now holds it but very slowly leaks when checking it. Is that ok? After all of the test I started pumping with the mity-vac on the door lock check valve and then started to unlock and lock the doors it worked only twice then i lost vac. Do I need to leave the car running to fill the vac tank in the trunk? What does this mean? And when I lock and unlock the master Vac switch makes a leaking sound. Is that whats leaking? How do I check that?

Reply With Quote
  #2  
Old 08-30-2006, 10:59 PM
Craig
Guest
 
Posts: n/a
The master switch is supposed to "vent" the vacuum when you lock/unlock the doors, so that sound is normal. You system is made up of a lock circuit (yellow/red lines) and an unlock circuit (yellow/green lines). There is a separate line (yellow/blue, I think) that runs from the check valve to the tank in the trunk. When you lock the doors, the unlock circuit vents through the master switch, and vice versa.

If you run the car for a couple of minutes it will pull a vacuum in the tank. How many times will the doors lock/unlock after the engine is shut off? Will the doors unlock/lock after the car has been sitting overnight? It's possible you have another small leak(s) someplace.
Reply With Quote
  #3  
Old 08-30-2006, 11:04 PM
18 year old benz newbie
 
Join Date: Aug 2006
Posts: 108
i have a 76 300d (115 chassis) and the only vacuum related component that works is the fuel door lock (only if you lock the car right after shutting engine off) which leads me to believe i have a HUGE leak somehwhere, and the car is not holding vacuum. door locks nor trunk lock via master lock system works- i want to get this fixed, but im having trouble pinpointing where the leak would be at. i can definaitly hear a small vacuum whoosh from the drivers side door though.
__________________
__________________________
76 300D 108,110 miles
99 Saturn sl1 80,000 miles - moms
91 Grand Marquis 45,000 miles - Grandparents
97 Ford F150 - 16,000 miles - Grandparents
73 Ford Monarch (parked 65,000 miles - Grandparents
Reply With Quote
  #4  
Old 08-31-2006, 01:45 AM
Banned
 
Join Date: Dec 2005
Location: CA... No. of S.F.
Posts: 890
My guess is...

Quote:
Originally Posted by 80300dbenz View Post
On my 1980 300D the door locks stoped working and i decided to test all the lines on the driver side floor and fron pass. side floor. One red and green line goes across to the fron passenger side floor and when i was testing those it wouldnt hold vac. All the others did except for the one going to the trunk element to i took it out and blocked it. It now holds it but very slowly leaks when checking it. Is that ok? After all of the test I started pumping with the mity-vac on the door lock check valve and then started to unlock and lock the doors it worked only twice then i lost vac. Do I need to leave the car running to fill the vac tank in the trunk? What does this mean? And when I lock and unlock the master Vac switch makes a leaking sound. Is that whats leaking? How do I check that?
Take a look at my diagram at: http://www.peachparts.com/shopforum/showthread.php?t=160169
which I put together after working on my Son's 1980 300D... and if you want a clearer copy, PM me with your regular e-mail address.

I think that the GREEN is for the " Lock " circuit and the RED is for the " UnLock " circuit... and I think you will find the the fuel door is on the same " Lock " circuit with the trunk... and the fuel door does not have an UnLock connection.

So my fast-and-dirty e-mail diagnostic "GUESS" is that you should check out the fuel door vacuum element.

Sam
Reply With Quote
  #5  
Old 08-31-2006, 10:16 AM
Biodiesel300TD's Avatar
|3iodiesel300T|)
 
Join Date: Dec 2004
Location: Albany, OR
Posts: 4,845
80300dbenz,
Sounds like maybe you have a leaky reservior. There should be another line in the engine bay that goes to the reservior. Mine is brown I believe. Pull vac on that and see if it holds. You may have a bad connector on the line that goes into the reservior. If that doesn't hold, find the connector and plug it and then pull vac again. Or just replace it. I would replace all of the connectors. They are a huge source of vac leak, and they are 25 years old.
__________________
Andrew
'04 Jetta TDI Wagon
'82 300TD ~ Winnie ~ Sold
'77 300D ~ Sold
Reply With Quote
  #6  
Old 08-31-2006, 01:59 PM
Banned
 
Join Date: Dec 2005
Location: CA... No. of S.F.
Posts: 890
Quote:
Originally Posted by 80300dbenz View Post
On my 1980 300D the door locks stoped working and i decided to test all the lines on the driver side floor and fron pass. side floor. One red and green line goes across to the fron passenger side floor and when i was testing those it wouldnt hold vac. All the others did except for the one going to the trunk element to i took it out and blocked it. It now holds it but very slowly leaks when checking it. Is that ok? After all of the test I started pumping with the mity-vac on the door lock check valve and then started to unlock and lock the doors it worked only twice then i lost vac. Do I need to leave the car running to fill the vac tank in the trunk? What does this mean? And when I lock and unlock the master Vac switch makes a leaking sound. Is that whats leaking? How do I check that?
80300dbenz - Have you tried to read the copy of my door lock diagram that is posted at:
http://www.peachparts.com/shopforu...d.php?t=160169 ??
I'm sorry I'm not back home where I could get you a much clearer copy.
Soon I will have the higher resolution diaghram files available on-line!

Biodiesel300TD - On our 1980 300D I found the hard vacuum line that runs to the reservoir is yellow with a dark stripe down it. Pulling a vacuum on this line is very laborous using a hand vacuum pump so I installed a "T" at the start of this line in the engine compartment and after the engine/pump had drawn a vacuum on the reservoir, then I shut off the engine and watched the vacuum. It should hold stead without any noticeable drop and YES, if there is a drop, there is a very good chance it is at the rubber grommet on the side of the reservoir in the trunk where the same hard plastic line is stuck throught the grommet. On my diagram I have a note that you can use non-hardening silicone sealer on inside and outside of a leaking grommet... taking care not to get the sealer inside the hard line.

I agree, any hard and/or cracked rubber vacuum fittings should be replaced for I don't silicone is appropriate... however if they are old but still reasonably soft what I did was to place them in a zip-loc bag, spray them with Armerol (sp?) and let them soak overnight. And one other technique I learned is to use the smaller plastic electrical tie binders and sinch them down tightly over the rubber fitting after the hard vacuum line is in place. Use pliers and/or vice grips to do the sinching! Afterall these fitting can cost anywhere from $3 to $12 each depending upon where you purchase! In hard to access locations I recommend new fittings.

Got to run to a Family REunion!
Sam
Reply With Quote
  #7  
Old 08-31-2006, 09:01 PM
Registered User
 
Join Date: Sep 2004
Posts: 8,971
Quote:
Originally Posted by Samuel M. Ross View Post

I think that the GREEN is for the " Lock " circuit and the RED is for the " UnLock " circuit
Normally it's the other way around.

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 05:32 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2024 Pelican Parts, LLC - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page