vacuum engine stop not working

[W123amb]

Hi guys, I have a BIG problem with the vacuum system and cant find a diagram to show the diesel engine shut off system.
Basically the previous owner ripped out most of the vacuum pipes so I have never had the door locks working! but this is not a worry at the moment.....first I need to get the thing to shut down !

This is what is left.......

From the vac pump to the servo is ok and there is a smaller pipe (brown) going directly to the ignition switch.
The brown pipe comes back to the diesel shut off valve direct from the ignition switch.
Under the rear parcel shelf there is a vacuum reserve tank which is piped all the way to the engine bay but not plumbed into anything.

As it is the engine switches off after about 5 minutes and the vacuum holds the stop valve down so there is no leaks there.
I need to know where to connect the rear reserve vacuum tank into the system to try to get the engine to shut off when the key is turned off rather than wait untill I have gone into the house and made a coffee before the engine stops !! Any help is appreciated PLEASE lol

 

[brandwooddixon]

Which vehicle is it again?
Is there not a fuel cutoff lever on the pump?

 

[W123amb]

it isa W123 diesel 240 1982 salloon/sedan

 

[television]

You say that many pipes are off,,,is there any suction on any of them when the car us running, if so they must be blocked off, is the vacuum pump running

What is the car please

 

[W123amb]

The vacuum pump is fine and the brakes are good the only pipe connected to the system is one from the main pump to brake servo/booster which has a brown pipe going to the ignition switch and from there back to the engine cut off valve on the diesel pump.
I would like to know where to connect the resevoir tank for the reserve vacuum to try to get the engine to close down quickly before I need to replace the engine mounts as it takes 5 minutes to stop the engine after the key is turned off. there are no leaks on the ignition switch or the shut off valve as the engine stop lever stays down when it eventually switches off.

 

[television]

What is the car please

 

[W123amb]

there is no suction on any of the other pipes as they are not connected to anything....unfortunatly !

 

[W123amb]

the car is a 1982 240D W123 salloon manual transmition diesel

 

[W123amb]

Behind all the door cards there is no central locking fitted, nor is there any pipes for this to be fitted. The only other vacuum system on the car is the headlight raise/lower control which is not connected at the moment as the system has a leak somewhere.
There was no vacuum resevoiir fitted when I got the car, but I have fitted one under the rear parcel shelf and run a pipe to the engine bay but have no idea into which line of the system I should put it ?

 

[television]

I am having some problems in finding the engine vacuum charts and hope fully I will find some,

I have all the connection pipes diagrams for the locking so no problem there

 

[W123amb]

LOL there is no pipework or actuators fitted for central locking, and it looks like there has never been any from new which is unusual as all my mercs had it. But on the bright side its one less problem to fix.
If I can figure out where to plumb in the reserve vacuum tank that might help close the engine more quickly, and then I can maybe try to sort out the leak on the raise/lower light system and re-connect it to the vacuum system.

 

[W123amb]

Behind all the door cards there is no central locking fitted, nor is there any pipes for this to be fitted. The only other vacuum system on the car is the headlight raise/lower control which is not connected at the moment as the system has a leak somewhere.
There was no vacuum resevoiir fitted when I got the car, but I have fitted one under the rear parcel shelf and run a pipe to the engine bay but have no idea into which line of the system I should put it ?

 

[television]

I will come back later on this

 

[wireman]

The pneumatic stop is simple, a pipe takes engine vacuum from the pump (a tapping on the servo pipe on my two) to the switch and then to the stop capsule on the pump, the pipes are brown.

No tank is involved or needed, the one fitted was I think for unlocking the central locking which I suspect has been removed.

I think you have a leak, it may be the capsules diaphragm has split, the valve on the steering lock being in need of attention or a coupling tube.

Tee a vacuum gauge into the pipe to the pump, run it and the vac should be zero, turn it off and you should get about 24"hg/0.8 Bar instantly and the engine should stop, the vacuum should hold (and the manual lever stay down) for as long as the key is turned off, days or weeks.

A minimum system vacuum of 0.4-0.5 Bar is required to stop the engine, test the vac at the servo pipe, expect at least 24". If insufficient vac is applied to the stop capsule the engine only slows down and vibrates like it wants to wreck the engine mounts until it stalls.

If no gauge is available pull the pipe from the pump, start the engine and switch off and the vac should pull at a finger tip placed over it, enough flow to make it fizz/hiss should be available. If there is evidence of engine oil inside the vac pipe the capsule is leaking.

When my 124 had exactly your symptoms it was the capsule to blame, awkward pig to change.
The manual stop must be fully depressed while the new capsule is inserted with its hook under the bail, if you don't the capsules hook will/might push the pumps metering/control rack instead of pulling it and the engine will over speed and self destruct as soon as you start it.

Edit
having re-read your original query I note that you have excluded a leak, so test the available vacuum, if its not low vac does it stop nicely with the manual lever? and does the manual lever get pulled down fully by the vacuum capsule when the key is turned off?

 

[W123amb]

When the engine stops after a few minutes the lever stays down for as long as the car is left......days, weeks........so I cant see where I have a leak as the ignition switch and the diaphragm on the shut off valve on the pump would release the stop lever if there was a leak ?
Also there is no evidence of engine oil inside the vac pipe....
The vac will pull at a finger tip placed over it, enough flow to make it fizz/hiss is available but the time from turning off the ignition switch to this happening is about 5 minutes ??

 

[W123amb]

the stop lever is fully down when the engine eventually stops and stays there untill the ignition is switched on again in 1 hour or 1 day... I assumed if there was a leak on the pump it would open up the stop lever after a few minutes ?
I also assume as the brakes are fine and the only other thing comming off the main vacuum line is the cut off pipe (brown) the vacuum is ok or I would have poor brakes ??..........this is really hurting my head now

 

[Doug1234]

I do not think you have any leaks in the stop lever diagphram.
Now it all works but takes time to stop and I presume when you go to start the engine it will start up as normal so I reckon it is something to do with the bit on the ignition barrel or a major vacuum leak at servo or the pipe to it.

So maybe ignition barrel part is loose so it is not getting fully opened to allow enough vacuum through to be able to work the stop capsule,you pull up in the car and turn off the key and then wait until it gets enough vacuum through to draw stop lever down.

The servo pipe has a leak and the vacuum pump has to empty out the servo before it can even have enough suck to work stop lever

 

[W123amb]

MMMMMMMMMMM that sounds interesting...I checked the main pipe visually but saw no sign of damage and no hissing noises so I better try to get the ignition switch off and check it.
It looks a nightmare of a job as I had the panels off and the clocks out just to check the vac pipes were intact, but I have no idea if or how to get this out ? is there an easy way to remove it or check it in place ? It has no leaks as far as I can work out as the stop lever would slowly release itself after shutting down the engine ( I think )

 

[wireman]

I assumed if there was a leak on the pump it would open up the stop lever after a few minutes
This is correct.

The vac will pull at a finger tip placed over it, enough flow to make it fizz/hiss is available but the time from turning off the ignition switch to this happening is about 5 minutes ??
Do you mean that it takes 5mins before it will suck? if so it is the valve on the steering lock at fault, either its blocked, shot at or not being correctly actuated.

From what I've seen of the Hymer set up the steering lock is a real pig to get at so why not bypass the existing pipework and valve to check it.

Acquire a piece of 4mm nylon pipe and connect it to the stop capsule, then apply it to the servo tapping and see if it stops correctly, if not there is something stopping the capsule or the mechanism it pulls travelling fully.

The stop capsule pulls up on a bell crank inside the pump governor housing which in turn pushes the pumps rack into the fully cut off position, if there is something wrong with this it may be the root cause, however the Bosch M pump is not known for going wrong mechanically, save for the odd fuel leak maybe.

A vacuum gauge and some readings would help greatly.

Does it stop immediately on the manual stop lever?

 

[brianbrian]

On the end of the ignition on your car is a valve with two vacuum pipes for starting and stopping engine, one maybe two screws holding it. If you cannot get the two scews out to change the valve, fit another valve for on and off under the dash and run two vacuum pipes, one to vacuum pump, one to diesel pump. but first do check it is the valve on the ignition. if you connect vacuum pipe from diesel pump straight to vacuum pipe on vacuum pump start car then disconnect while running this will tell you if the valve on the ignition was working or not. Head lights just one vacuum pipe from each head light to switch and one pipe from switch to vacuum pump. Hope this helps if not will give you my phone number and talk you through it.