Author Topic: What is the fender reservoir for ??  (Read 3851 times)

1980sdga

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What is the fender reservoir for ??
« on: 17 May 2011, 04:09 PM »
In my engine compartment (1980 300SD) I have 3 lines coming off the main vacuum pump line.

The black one runs to the ALDA and down to the transmission.

The grey one runs up by the booster and feeds the trunk reservoir, ACC, cruise, shut off valve and door locks.

There is a 3rd translucent white line that is larger than the others. It runs into the cabin where there is a 3 way connector.  One of mine had an open leg but I found a line that I believe hooks up to it.  It's the white color as well and the same diameter.

One of the lines runs behind the kick panel (It must be going to the "double-ball" reservoir) and the other line runs over to the passenger side.

Any ideas?  It appears "special" because it's larger than the other lines and has it's own one-way valve where it branches off the main trunk.

I'm soooo close to having this thing sorted  ;D
Jon


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WGB

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Re: What is the fender reservoir for ??
« Reply #1 on: 17 May 2011, 07:30 PM »
The colours of the vacuum lines are given in the workshop manual including diagnostic checklists.

Generally large gray lines are main vacuum feed lines but there are three generations of colours and if original the list can be found in the workshop manual.

Bill

jbrasile

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Re: What is the fender reservoir for ??
« Reply #2 on: 17 May 2011, 07:36 PM »
1980sdga,

I posted in another topic, but here it goes again.... the vacuum reservoir under the driver's side fender is for the climate control system.

Tks,

Joe

1980sdga

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Re: What is the fender reservoir for ??
« Reply #3 on: 17 May 2011, 08:53 PM »
Wow, I'm confused  ???  Maybe this'll help.

This is what I started with under the hood. Kind of hard to see what's going on so I carefully checked all these circuits and chased from there using the vacuum diagrams. (Never mind the fuse box. Another project  :-\)

original

In this pic you can see more of what's going on.  I'm tooo familiar with these hoses. I've followed them for miles.  ;D

 worked

The grey line (Under the zip tie fastened to the AC hose) comes off the main vacuum pump line.

Starting bottom leftnear the corner of the fuse box is black/yellow for the cruise.

The yellow hose at the bottom (Top right of the fuse box) is power locks. It branches to the doors, a bundle across the dash and all the way to the rear of the car for gas lid/trunk.

The next one up is yellow/black and goes directly to the reservoir in the trunk. It feeds the other systems from the bundle pictured. (Funny, I was picturing a main suction line going to it and some others branching off from the reservoir itself.)

Then the dreaded green and black  ;D  It runs to the ACC panel and all the circuits (That I could find in the ACC vacuum diagram) for the AC branch from there to the servo, to pods, to switches,  everywhere!

The next brown line runs to the key switch and the brown line above it returns to the shut off valve.

You can see the check valve that prevents the trunk reservoir and locks from bleeding down through the pump. Weird that the cruise is also in that part of the circuit. Maybe a more constant steady vacuum source?

The green ACC line and the shut off valve are outside the reservoir part of the circuit and rely solely on the Vacuum pump for operation. Maybe since there are some controlled bleeds in the AC that would also bleed the reservoir?

The circuit that has me confused is the dirty white line that starts with the red rubber center left. It has it's own unique check valve coming off the vacuum pump line.  It goes into the cabin and was originally connected to a line that goes under the dash and tucks into an area in the pass. footwell and it had a 3 way splitter with one open leg.  I searched around and found another identical hard plastic line that sure looked like it belonged in the open 3 way.  

This open line and the open splitter was behind the instrument cluster.

I found this picture that seems to show the circuit tied into the AC but I tested my AC system with and without the white line connected and it didn't make any difference at all.

 schem

So I guess the AC system has a circuit within a circuit with it's own reservoir?  The green line seemed to run the whole thing fine and according to the ACC service manual.

I swear, I tested every line on the ACC vacuum diagram. I even used a crayon to mark each line as I was testing and kept going until I had colored every line  :P  and none of this was on it.

If you look at #150 on the diagram, that's where my open 3 way was and it doesn't appear to lead into the engine bay.  

Everything works fine (as far as I can tell) but it looks like I have something wrong.

I'm having trouble viewing the workshop manuals.  Gotta work on that.

Here's the vacuum diagram:



Sorry it's a pic but I couldn't get it from the manual as a single page  :-\

You can see 31, 32 and 33. The line coming from them is the green/black going into the switch panel. And it does indeed show the "3 ball" reservior.  I tested every line on this diagram...

I need to get the "multipage TIFF" thing worked out so I can see the workshop manuals. 
« Last Edit: 17 May 2011, 09:36 PM by 1980sdga »
Jon


Little by little I have grown fond of the infamous Auto Temp II we have in our 116's

calvin streeting

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Re: What is the fender reservoir for ??
« Reply #4 on: 18 May 2011, 12:18 AM »

I'm having trouble viewing the workshop manuals.  Gotta work on that.

I need to get the "multipage TIFF" thing worked out so I can see the workshop manuals. 

I have a converted them to PDF, and OCR (text reconitioned) them, to make them word search able. And I emailed the admin, about replaceing them, but have had no reply yet...

calvin

jbrasile

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Re: What is the fender reservoir for ??
« Reply #5 on: 18 May 2011, 07:28 AM »
1980sdga,

You are missing some check valves for starters.

Let's start by checking the connections for the eng shut off system, here is the diagram from the Service Manual Library



Hope it's not too small...

As you can see there is a vent line (black on the diagram, that is not connected to anything), check to make sure your car has this system hooked up correctly.

Now, as far as the acc, locks and creuise:

The 3 systems are sort if interconnected with a check valve at each end to prevent vacuum from escaping, I am getting a diagram ready and will post it later today.

One interesting thing I did not know is that the line that feeds the cruise control shares pressure with the power lock vacuum tank.

Tks,

Joe

1980sdga

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Re: What is the fender reservoir for ??
« Reply #6 on: 18 May 2011, 10:11 AM »
Thanks again Joe!  I believe my shutoff system is OK. I have a non EGR so it greatly simplifies engine hose routing  :)

I just re-checked my reservoir system and I think I may have it figured out.  I pulled a vacuum on both tanks last night and they are holding well  :D  Good signs.

I wish I knew where the large off white line that runs into the passenger side fender went to  ???  I have a line running from the vacuum pump, into the cabin, to a "3-way" where one leg goes to the reservoir in the drivers fender and the other leg crosses the dash and runs into the SAME SPOT in the passenger fender  ???  There's about 1 foot of the line that I cannot actually see directly under the center of the dash but I don't see any branches or lines that are not accounted for in the vacuum diagram...0

My guess is that it's going to some kind of device that maintains a specified vacuum in the system, or another reservoir??

This is the way it's hooked up now and it functions fine:



I just put everything under the hood back like I found it but there was an open leg on what I believe is this junction behind the dash:



The answer lies in this 3 way connector.  I'm afraid to just hook the green line into the reservoir system but I believe it's the way it's supposed to go...
Jon


Little by little I have grown fond of the infamous Auto Temp II we have in our 116's

jbrasile

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Re: What is the fender reservoir for ??
« Reply #7 on: 18 May 2011, 03:39 PM »
1980sdga,

I am as puzzled as you are regarding this off white thick vacuum tube.... after checking everywhere it does not show up in any schematics. Also, the car only has two reservoirs, the one in the trunk and the one under the left fender, nothing on the right.

I checked my car too and even though it is not a diesel, the systems are identical minus the engine shut off feature.

I was able to find this great illustration of the vacuum connections on an early 123 diesel which is basically the same as the 300SD.

Take a look at it but it goes like this:

Vacuum source connected to a 4 piece

4 piece takes:  2 check valves and the brown line from inside the car which is the vacuum feed for the key, the brown line does not have a check valve

Check valve c takes a 3 piece which takes:  red/black - acc panel and green/black - left fender reservoir

Check valve d takes a 4 piece which takes: yellow/gray - door switch, yellow - trunk reservoir and black/yellow - cruise control actuator.



From your pictures you are missing:

1 check valve and perhaps 1 or two 4 pieces.

Have you disconnected this thick off white line to see if it affects anything?

I believe that if you follow the diagram pictured you should be able to have everything function correctly. I even changed the connections in the 78 450SEL because my cruise control line was not connected together with the trunk reservoir and that could be the cause of a loss of speed going uphill as well as a slight accel/deccel variation.

We are probably close to figuring out all the mysteries of MB's vacuum engineering, hehehe....

Let us know what you find.

Tks,

Joe

jbrasile

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Re: What is the fender reservoir for ??
« Reply #8 on: 18 May 2011, 03:55 PM »
1980sdga, I think I figured it out!!!

You are missing the line that goes into the acc panel, it should be either green/yellow (later 116's) or red/black (as my 450) but I don't see it in your pictures. I think they ran that off white line straight from the vacuum pump/source into a 3 way and from there probably one leg into the acc panel, you need to check the other leg and see where it leads, this is actually wrong. You should probably replace that line with one of the correct gauge and have it connected to the 3 way that feeds the left fender reservoir and to the acc panel, that's it.

Let me know if it makes sense.

Tks,

Joe


1980sdga

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Re: What is the fender reservoir for ??
« Reply #9 on: 18 May 2011, 09:07 PM »
Been fooling with it all day.  Back on the road Friday so I'm enjoying it although it's frustrating.

I have 2 1980 SD's so I've been comparing today  ;D

I checked out the one I'm not working on and found that the large white hoses were hooked up to a 3 way behind the gauges.  One to the right fender, one behind the dash to the other fender and one to a big check valve on the main trunk.

Here's a pic:



I had the same thought you did. In fact, on the car I'm working on the line running to the ACC switch is about 5 cm long and BLACK.  It's connected to the green/black by a rubber hose connector.  I was sure that it connected to the large white tube under the dash but then I looked at the other car to compare...   Same thing.

I'm beginning to believe that I'm looking at the vacuum diagram wrong. It shows 31, 32 and 33 and the connections between them but I think it leaves some of the other circuits out. I think that check valve 32 is the big one with the pink hose. and the vacuum travels through the check valve on the main trunk between the grey line (Which feeds everything except the lock mechanism) and the large white line.

The connections at the brake booster where everything enters the cabin was the same on both cars as well.  Even the location of the blue/black check valve so that part must be right as well.  The one I'm working on just has a different more "spread out" configuration. I'll eventually replace the original "spiders" but this helps me troubleshoot  ;D

Last night I hooked my mity vac to the large white line where it connects to the main trunk (This is on the car I'm working on) and pulled it down to 5 in/hg and marked it with a piece of tape. This morning it hadn't budged off the mark.  Maybe there's just a plug behind the fender  ???  At least the fender reservoir is holding!  I was actually thinking that maybe the the line that dissapeared behind the passenger fender ran the fuel door and trunk lock somehow but that isn't the case... Those lines run behind the back seat on the passenger side.

I also ran the engine and pumped the lock system down to about 15 in/hg and marked the gauge with tape. This morning it hadn't budged  :D ;D :D  I cycled the locks about 5 times before it bled down. I'm not sure if it should "consume" vacuum like that but I can live with it. I can actually hear a little hiss at the drivers door when the key is turned and the gauge drops.  (Good idea to leave the windows down when fooling with locks  ;D)

The AC works fine (Well, it did, and it didn't,now it does  electrical stuff ::)) the flaps flap properly. The center vents don't blow with the heat so when changing from hot/cold they open and close and the leg vents open.  The cruise control works some times  :P  It continues to accelerate with the cruise stalk so I believe the vacuum part is functioning.

The strange thing is that the AC vacuum system only works for a couple of minutes after the engine is turned off. I thought that the vacuum reservoir would keep parts of it working similar to the way the door locks work but it doesn't seem to be that way...

All the locks work. I just keep locking and unlocking just to watch and hear it work  ;D

Sorry so longwinded but I've been on it all day  ;D

Oh yea, do you think you could get a replacement check valve? It's the big one connected to the pink hose.

Jon
Jon


Little by little I have grown fond of the infamous Auto Temp II we have in our 116's

Papalangi

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Re: What is the fender reservoir for ??
« Reply #10 on: 18 May 2011, 11:32 PM »
Quote; The strange thing is that the AC vacuum system only works for a couple of minutes after the engine is turned off. I thought that the vacuum reservoir would keep parts of it working similar to the way the door locks work but it doesn't seem to be that way...

Item 38 is a controlled leak and will drain the AC vacuum.  The door locks are rated for about 5 cycles according to some manual I saw somewhere so you are doing very well there.

Michael
1976 450SEL, 116.033  Sold it to buy a '97 Crown Vic.  Made sense at the time.
1971 250C, 114.023      Sad but true, it's gone to a new home.
1976 280C  Stolen by the City of Seattle, sort of.
1970 250/8, traded in on a 1993 Land Rover Disco

1980sdga

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Re: What is the fender reservoir for ??
« Reply #11 on: 19 May 2011, 09:58 AM »
Quote; The strange thing is that the AC vacuum system only works for a couple of minutes after the engine is turned off. I thought that the vacuum reservoir would keep parts of it working similar to the way the door locks work but it doesn't seem to be that way...

Item 38 is a controlled leak and will drain the AC vacuum.  The door locks are rated for about 5 cycles according to some manual I saw somewhere so you are doing very well there.

Michael

I locked the doors last night and this morning I got an UNLOCK, LOCK, UNLOCK, LOCK, UNLOCK, and a last, rather wimpy LOCK.

I'm pleased with it  :D

I buttoned up the drivers side last night and went for a test drive and the AC was working well and then it stopped responding to the thumb wheel  :-[ :-\ :'(

I got home and quickly traced it to the ACC amp. I had a spare that I installed and it began working again  :P

I'm getting pretty good at troubleshooting the system.  Not sure if that's good or bad  ::)
Jon


Little by little I have grown fond of the infamous Auto Temp II we have in our 116's