Ok, before I start I will say that I have looked at the vacuum diagrams in the sticky but they haven't helped me yet.

I have a 1981 300D automatic and I am having some issues.

First some background.

When I bought it, it would shift only at high rpms and I discovered that this was because the vacuum modulator was bad (it wouldn't hold a vacuum).

I replaced this and it began to shift WAY too early. I then adjusted the modulator and nothing happened. When I checked the new modulator again it wouldn't hold a vacuum any more.

I am at the point now that I just want it to shift the way it was shifting and I will deal with it.

To complicate matters, I broke the throttle nipple on the brake booster vacuum line somewhere along the way. I bought a replacement but it doesn't look exactly like the one I had. The line seems to be a bit too long and the nipples aren't in the same place. I got it at the dealership and it looks like the ones I could find on ebay but I didn't get because it looked different.

I also in the middle of this mess decided to remove the vacuum stuff on the valve cover and reattach the lines like it has been suggested elsewhere on the forum.

Now, it still shifts way too early even with the vacuum line removed from the transmission altogether and I can't get it to get up to speed. It is like the transmission is in too high a gear and the engine just bogs down on hills and won't ever get up to speed like it should. I can shift it manually but it still doesn't seem to be accelerating as well as it should be.

It also doesn't shut off properly. It did when I bought it, albeit a little delayed, but now it won't.

I do have a mighty vac (at least a craftsman version) and have used it to determine that the trans. modulator is not holding a vacuum.

I have checked the forum but nothing seems to be exactly what I need. The diagrams don't quite seem to match up.

I also don't need my locks to work I just want it to run and shift properly and then shut off when I turn off the key.

Thanks for the help

What I want to know is what is the base minimum vacuum setup you can have and still have everything work

Shift points are controled by the bowden cable on most 123's. It's a cable that is attached to the top of the valve cover. Try adjusting it. If you turn the adjusting nut one way it will lower the shift points, and if you turn it the other way it will raise the shift points. I don't remember which way does what.

Adjusting this may help the shifts a lot.

With vac issues it's best to start at the main vac line and work you way through the systems. You can rule things out a lot quicker this way. At long as the new main vac line has the correct number of barbs on it, it should still work, as long as the length isn't too much.

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It does have two nipples on it and is only a few inches too long in my estimation since it just curves up a little where the other one was straight.

Where exactly is the Bowden cable?

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1993 W124 300D
-297K on the clock as I type this.

On mine it's on the bracket on the cam cover with that accordion looking rubber piece. Measure the white plastic part before you adjust. This is the CD. (file photo)

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83 SD

84 CD

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1981 300D's do not have bowden cables.

I looked for one on mine for a long time untill someone told me.

Does a 1981 300 D have a bowden cable ?

Thanks
RichC

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When the power of love overcomes the love of power the world will know peace.
Jimi Hendrix

I wondered about that. Burned into memory now.

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Sorry about that.

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83 SD

84 CD

Hello, guys

I think what I said was misleading.
It was a good while back that I found out about the missing bowden cable on my 81 300D
Not during this post.
You did not cause me to search in vein.
I did the searching on my own, a good while back.

Sorry for the misleading post.

Have Fun
RichC

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When the power of love overcomes the love of power the world will know peace.
Jimi Hendrix