W123 Vacuum Progress….

[dot]

@John757 thank you I‘ve just seen this, all good info.

I hooked up my smoke tester again today as I was convinced there must still be a leak somewhere. And what do you know, it was underneath the car, coming from the (red) gearbox modulator.

So I isolated that with a golf tee and went out on a test run. The gearchange was the same as always, slightly jerky 1-2, then Fairly smooth to be honest. I let the vacuum build up, and then turned the key off and… yes the engine stopped! And the door locks, fuel flap and boot all locked and unlocked as they should. Success at last.

So I happened to have a NOS modulator to hand, but watching a YouTube video on this subject I picked up that there are differences between the red (which is fitted atm) and green (the NOS I have). Can anyone tell me if I’ve got the wrong part or will I be ok? It’s a 722.4 box.

Please note 1980s Capital Radio 194 key ring and by complete coincidence sounds of the 80s on the radio with a touch of Kim Wilde!

Here’s a short vid…

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[G7Wagen]

From the 722.3/4 manual hope it helps... Great Progress BTW
File size for whole manual too big to upload.. 4mb ping me your email in a pm and I will send it to you.

Enclosed is also trans adjustment procedure in pdf.

(Very early sprinter diesels used vacuum off ignition)

 

[dot]

So I've gone ahead today and tried to remove the Modulator. Just to give background this gearbox was rebuilt by a good firm in Fakenham, Norfolk a while back and hadn't been used since because the Neutral Safety was broken.

So with various forms of 5mm Allen key/socket I've attempted to undo the mod. The right hand side one was tight but I was able to crack it anti-clockwise, but the left hand side was was stuck fast, and had rounded. Now I don't know if the gearbox firm impact-wrenched it in that tight that the rounding had begun, or if I've done it, but I'm now in a position where with the poor access and so on am I looking at gearbox removal to get at this, or are there alternatives I'm not yet aware of?

Help!

Thanks, Dot

 

[Bellow]

There's a few things to try.
1) Try knocking the retaining plate ACW and see if it takes the bolt with. I appreciate there's not much freedom of movement for the plate before it fouls the gearbox case but it only need move a small amount. If it does, wrap the end of your Allen key in tin foil so it is a more snug fit in the bolt head and try and remove it.
2) Try turning the bolt clockwise to break it's seal. If it moves, as above to remove.
3) Knock it ACW with a well aimed cold cut chisel until slack enough to remove as per above. This is probably the most likely method that will remove it but as the others are more gentle - try them first.

A good penetrant will help - but you've probably got WD40.
If the car is still drivable, pop the other bolt back in and go drive for half an hour. The heat will help.

 

[gassygassy]

Hi. I am new to this thread and have read it all. I have a 1981 / 1983 W123 2.0 saloon with central locking that doesn't work so I have read most of the threads to try and find out why. My car is first reg in UK as 16 June 1983 but from the VIN and enquiring at the main dealer, and looking at things like the position of the heater blower motor I am now convinced it is a 1981.
So far I have removed and dismantled the driver's door vacuum switch, which an engineer friend told me is called a Shuttle Valve. This is apparently a well known engineering device. I have removed it, it wasn't dirty at all as in some pictures here. I smeared it in silicone grease and to my mind it still moved to and fro too easily for my liking. I thought it might be leaking around the seals. I removed the seals and packed a few turns of PTFE tape in the groove to spread the seals out. It still didn't work. I went to the Mercedes dealer and he could look up the part number and price (£87 inc VAT) but as you know they are not available from the main dealer. I see they are advertised new on the internet but I don't want to chuck money down the drain if it isn't the shuttle valve.
I made a smoke generator as per a you tube vidoe using a jam jar with schrader inlet valve to connect to a tyre pump but it didn't work, the smoke such as it was just disappeared into the bowels of the car and I couldn't see any emerging anywhere.
I don't have a vacuum pump - that will be because it is a petrol engine which produces enough at the inlet manifold whereas a diesel doesn't.
The brake servo works well, so the problem is not a lack of vacuum. I am a retired gas wallah so I have a manometer which I used to test the vacuum but the water in it was just sucked very quickly into the engine, so a) there is a good vacuum and b) it is far too good for the rather pathetic gas testing manometer. Anyway the problem is not a lack of vacuum.
I have been to a good engineering shop to see if they had O rings that would replace the cup rings originally fitted but they don't. I can't find any cup rings.
I should say that once or twice, in probably the last fifty times of operating the door key, all the doors did lock. I therefore think the actual door lock actuators are intact.

Is there a fault finding routine anywhere that I can run through? If I need to buy a smoke machine what specification in terms of volume output should I be looking for? I tried using gas fire flue smoke pellets in the jam jar but as I say I couldn't see any smoke emerging anywhere.

 

[Bellow]

I can't find any cup rings.

Someone needs to knock up a mould and cast them in RTV.

 

[optimusprime]

And another good site .All you W123 opwners need this

Diesel Mercedes | Woods and Barclay Automotive | Roswell GA

Restoring Classic Diesel Mercedes Is Our Passion. Woods and Barclay Automotive.

www.woodsandbarclay.com

 

[gassygassy]

My thread sbove was duplicated for some reason unknown to me so I have edit / deleted the copy. Ebay did that the other day, I had one item for sale and they posted the advert twice.
Not that I have got twitchy fingers you understand . . . .

 

[gassygassy]

What do people think would be the demand for replacement cup rings for the master vacuum switch / shuttle valve? Some years ago when reversing sensors were only available on BMWs, a friend and I designed one, and cutting a long story short, we got it appoved as a Rover Approved Accessory, manufactured and sold thousands of them. In the process we needed a special moulding done and once the tooling costs were paid, the housings for the sensors were about 10p each. I would hazard a guess that if we wanted a thousand of these ?silicone? cup rings, they would be less than 10p each which would be worth doing if everyone who has a suitably equipped MB wanted them.
By the way I approached Mercedes Benz at the motor show and said we are making reversing sensors, are you interested? The response was
"Are you accusing our drivers of not being able to reverse safely? . . . . Get off our stand!" I left with a footprint in my bottom.
Jaguar said :
" Does that mean we would have to put holes in the bumper to take the sensors? Our customers will never stand for having holes drilled in their bumpers. Go away".
Such are the difficulties of introducing a new safety feature.

 

[gassygassy]

@John757 I still haven't fixed my central locking. I have a W123 probably 1980 / 1 2.0 petrol. Is there a flow chart to find vacuum problems? I do have a good vacuum at the inlet manifold, and very commonly some of the doors lock all by themselves with no door lock key actuation.
If I could find a flow chart I could follow it through the system. The auto box works perfectly and so far as I can tell the vacuum tank seal under the rear parcel shelf is intact. I have stripped the shuttle valve and can't see anything wrong with it.

 

[optimusprime]

Check this out Look in here Diesel Mercedes | Woods and Barclay Automotive | Roswell GA

 

[gassygassy]

Check this out Look in here Diesel Mercedes | Woods and Barclay Automotive | Roswell GA

Nah. It's Left Hand Drive

 

[optimusprime]

Try this W123 Vacuum Diagrams and Troubleshooting Information. – Try this at home!

 

[gassygassy]

Hmmm. That link doesn't work optimus. But it sounds like it might be useful.

Aha. I got to the link by copy/paste the URL. Thanks, I'll look through it.

 

[optimusprime]

And this could help you Model 123 Maintenance Manual Index

 

[gassygassy]

Aha, that is excellent optimusprime. Thank you. That video found a leak in the fuel lock actuator - about the least essential of them all but nevertheless worth doing to make everything work and I like the way he is a practical bloke, showing you how to crawl into the boot and peer upwards!

Tell you what, the more you take these cars apart the more you realise what good value they were when new, about twice the price of a Ford, but boy there is a lot more to them than just twice a Ford.

 

[Stratman]

While you're in the boot looking upwards take a look at the structural panel under the parcel shelf...

 

[gassygassy]

Why? is it particularly scenic? Or are you implying that it will be falling to bits?

 

[Stratman]

It mostly affects coupes, but water can leak around the rear screen and corrode the structural panel underneath. It's a big job to fix.

 

[gassygassy]

OEEK! The mind boggles what it would cost. I have a regular saloon without much water in the boot. Not enough to warrant drilling a hole in it to drain, that is!
The other day I got in and sat on a wet driver's seat. I pulled the sun visor down and a waterfall gave me a hair wash. OK that's a bit of an exaggeration. I opened the sun roof (when it stopped raining) and found a strange stainless steel lever ramp thing that flips the black plastic wind deflector down when the sun roof is shut. It was loose, having detached from its mountings. I compared it with the other side, figured out how it should fit and refitted it using two very small but long screws, waxoyled the rain channel areas and it's OK now. One day I'll look up cleaning out the rain drain tubes . . . . . . I have a fear that they may be rusty so if I go poking a metal wire down there, I might just poke through the wall of the tubes.