[BoSondergaard]

Hello fellow addicts.
This is my first post. But I have like most people been using this brilliant forum to educate my self on w123's.

Well, my name is Bo and I'm living in Denmark along with my w123-230e and 230ce. The 230ce has been bought a week ago and is having a few issues. In general mostly with the gearbox.

It is shifting very hard between all gears and I can also feel the downshifts when braking to a stop.
I went under the car today only to find that there was no vacuum-line connected to the modulator on the gearbox.. In the engine-compartment I found a vacuum-line not attached behind the left headlight unit. (Just lying there sucking air). This line was nowhere near long enough to reach the gearbox, perhaps it has been cut or broken somehow? But bought some extra line and connected the two.. After this, the shifts went a little better but still hard. Then I went to turning the modulator half a turn and took a testdrive.. Better.. So went ahead with another half a turn.. Perfect :-D.

My question is then: Do you think this vacuum-line is meant to go there? Vacuum to the headlights are fine. And have I done something bad to the modulator? All SEEMS well now...

Maybe I should just ad that I don't have any access to equipment that can tell me the amount of vacuum in the modulator :-(

Hope to hear from you.

Bo.

 

[Stretch]

Hi Bo welcome to the forum.

I'm just a bit to the South of you and relatively new here too. There's a chap called Govert (also in Holland) who is undoubtedly the expert on the subject on this forum - he's contributed to lots of vacuum related threads here but this is the one to read:-

http://www.benzworld.org/forums/w12...3-transmission-diagnose-adjustment-722-a.html

It sounds like you've done the hard work but as you don't have a vacuum tester perhaps it is worthwhile checking the shift points (data in link posted above)

 

[BoSondergaard]

Hi in Holland.

Thanks for the link. I have seen this thread before in my search and my shiftpoints are almost to specs. Great reading though and it makes a lot of sense.

 

[Govert70227]

There should be a vacuum line from the intake manifold to the modulator, colour is usually black. There is a variable vacuum in the intake manifold, depending on the position of the throttle.

A vacuum line behind the light unit is usually for the headlight adjustment. You say the vacuum headlight adjustment works, do both units have a vacuum line attached and is the vacuum line you have found "extra"?

The vacuum for the headlight adjustment is a constant vacuum, that cannot be used for the transmission.

Connect a vacuum line from the intake manifold to the modulator. Adjust modulator so that the shifts aren't hard or that the transmission isn't slipping. The correct way to adjust the modulator is by attaching a pressure gauge to the transmission and turning the modulator so that the correct pressure is achieved.

 

[Stretch]

Bo it might be worthwhile looking at the vacuum diagrams as well. There is one line on my W123 300D that is meant to be left open - it goes through the rubber spiky alien hat looking thing close to the steering shaft (looking at the brake booster down a bit to the left - looking at the steering box up a bit to the left) into the cabin. My car is in bits at the moment so I can't check but I think mine's a purple vacuum line that is the cabin vent.

 

[Govert70227]

On petrol cars it is slightly different, they don't like loose-lying vacuum lines. Diesels have a Vacuum Control Valve to emulate the variable vacuum in the intake manifold of petrol engines and a vent line is needed. Petrol cars don't have a need for a vacuum control valve.

 

[Stretch]

On petrol cars it is slightly different, they don't like loose-lying vacuum lines. Diesels have a Vacuum Control Valve to emulate the variable vacuum in the intake manifold of petrol engines and a vent line is needed. Petrol cars don't have a need for a vacuum control valve.

Ah ha! Good to know - thanks.

 

[BoSondergaard]

Well, at least I'm now certain that it's not connected the right way.

I'm now situated in Germany where my 230e everyday driver is. The car in this topic is back in Denmark and I will not be able to visit it for 5 days.

But I can now see that the line I've been connecting to the transmission is the yellow/purple one in the following picture. It seems however that it should be connected to a place just under the distributer! What a mess I think it must be the timing advance.

But can anyone point me in the right direction as to where me transmission line then should be attached?

I guess it's kind of strange that the car even drives...

 

[Govert70227]

I think that is the decel shut-off valve.

The transmission vacuum line should be connected to the intake manifold. There are more connectors, you might want to remove the air filter housing first. Look in the area where the brake booster line and timing advance vacuum line are connected, there should be a nipple where you can connect the vacuum line.