I'm back after a 5 year hiatus as a Benz owner and I'm pleased to see that the ShopForum is still going as strong as ever. I did do searches before and after my recent acquisition that has brought me back to the forum, but could not find exactly what I am looking for.

Here's the car: http://www.flickr.com/photos/61049394@N00/4028374138/

a 1973 280 (w114) gasoline. It has the flat top inline 6 cylinder with the plugs down the middle.

I bought it knowing the transmission flared because 1.) the tranny was way overfilled with fluid (I pumped a quart out to get it to the top fill line) and having read numerous posts, I was cautiously optimistic that it would be a vacuum leak or other maladjustment that could be rectified. Plus it only has 87,500 miles on it.

So it shifts early, and flares between 2-3. It also does not shift into 4th. The local independent Mercedes mechanic (everyone in Lansing, MI will know who that is) has not examined the car but looked it up and said that he thought the 280 only came with a 3 speed in 1973. So that may solve that.

My questions:
1. Where can I find the transmission type? 722.102 and 722.202 are listed as possible transmissions and I can’t find a chart for it. Once I’ve identified the type, will it signify whether it is a 3 speed or 4 speed?
2. Where is the vacuum modulator? Does it even have one? From the articles I’ve read (including Steve Brotherton’s article on vacuum control), I don’t draw the conclusion that ALL Benzes have the vacuum control of the transmission. The threads that I find are usually in the Diesel discussion and that is what I had before.
3. Is there a book or manual out there that I can get that will have info about the 114? I looked at the info at MZF-Bayer Transmissions and they seem much simpler than my setup. I also don’t recognize some of the parts from the diagram. The MBUSA manual specifically excludes transmission rebuilds. A rebuild is beyond my skillset, but perhaps it contains all the necessary information short of that. Any advice here would be great.
4. Can anyone tell me what I am looking at in the following pictures? Descriptions are under the photo on Flickr.

1.
http://www.flickr.com/photos/61049394@N00/4027505397/

2. There is a wire going into that grey mass. But no vacuum line.
http://www.flickr.com/photos/61049394@N00/4028257706/

3. There is a little silver valve with a vacuum line going to it behind the bar there, but I can’t figure any way of adjusting it.
http://www.flickr.com/photos/61049394@N00/4028258926

Some answers.




I bought it knowing the transmission flared because

Usually an indication of a transmission rebuild needed. You can change the filter and fluid, adjust the modulator, ensure the shift point rod is adjusted correctly and you might get lucky but probably not.

87K on a 1973? I think not.


So it shifts early, and flares between 2-3. It also does not shift into 4th.

It does have a 4 speed auto. 1st gear is almost never engaged unless you manually shift it through the gears.

My questions:
1. Where can I find the transmission type? 722.102 and 722.202 are listed as possible transmissions and I can’t find a chart for it.

Originally was a 722.2XX

2. Where is the vacuum modulator? Does it even have one? From the articles I’ve read (including Steve Brotherton’s article on vacuum control), I don’t draw the conclusion that ALL Benzes have the vacuum control of the transmission. The threads that I find are usually in the Diesel discussion and that is what I had before.

Located on the right hand side of the transmission above the pan. Follow the vacuum line. To adjust, remove the banjo bolt, if fluid comes out the modulator is bad, insert an allen wrench (I think it's a 5mm) and turn for adjustment. CW for faster, harder shifts. Put a vacuum gauge on the line BEFORE adjusting to check the pressure.

Thanks, Mike D.

That is exactly what I needed to know. I'll go look for the banjo bolt tomorrow night. When you say right side, that means passenger side on a US car, correct? If it is what I think it is, there is fluid leaking from it and that may indicate the source of my problem.

I'm glad there is a fourth gear. It was supposed to have a top speed of 112mph and with the current state of the transmisison, I don't want to drive more than 70.

I'll look for more information on where to put the vacuum tester to start with.

If it has more than 87k on it, then it was "fixed" a long time ago, I've got spotty records going back to 2000 that seem to corraborate everything.

The "sides" of automobiles are determined by their orientation when sitting in the driver's seat. This eliminates the LHD, RHD, "curb side", "road side" confusion, well, most of the time anyway.

I suppose I should have said "banjo fitting". The bolt is simply a hollow bolt holding the "banjo fitting" to the modulator. There are crush washers on each side of the line. They will drop and roll under that bench wayyy over there, the one encrusted with spider webs, you know, the one which ate your 13 MM socket. Be ready for them and catch them when you pull the bolt because, of course, they are aluminum and laugh at magnets!

The M110 revs pretty high at highway speeds but it was designed to do so.

In 2000 the car was already 27 years old. That would come out to an average use per week of about 62 miles. I suppose, if the church was 30 miles away and the little old lady was frugal, it could be true.

Alright, I replaced the vacuum modulator. No leaks and all seems to be installed right. Thanks to Mike D for helping me identify it. The old one was definitely trashed. You could see the spring inside had broken and was visible from the side where you should see the allen bolt only. I don't actually know if there is still an allen bolt in it as the spring is all jamming the orifice so you can't see.

It didn't change shifting much. Still no 4th gear and still a little flaring between 2-3. Not as much as before, and it runs stronger as well. I adjusted the allen bolt 3/4 turn clockwise before it started feeling hard to turn.

I stopped as I had two conflicting recollections of the mechanic I purchased the vacuum modulator from telling me to turn it 1 or 2 complete revolutions to adjust, and someone else telling me to turn it 1/4 turn at a time. I suspect it may have something to do with different styles of vacuum modulator. I have the old style (no plastic). Anyway, I'm looking for clarification before I go crank it too hard.

Anyone know if you can crank it too hard? Can I puncture something in there?

I did things a little backward as most recommendations suggest
checking vacuum lines first. I figured that I would replace the vacuum modulator immediately as it was definitely leaking. So now I'm off to the vacuum lines. Hopefully Monday. I'm going to start at what I think is the vacuum manifold. It's just behind the carbs and it seems the line going to the transmission is metal.

Anyone have a better diagram than the one at mzf bayern? That one seems to be missing a few parts and labels.

BTW, MikeD, I am beginning to think your skepticism of the mileage is warranted. I found an extra speedometer? cable going from a metal box on the left front fender with vaccum lines going into it. There is a newer looking speedometer cable going down the the transmission which records apparently accurate speed. Could this vacuum/speedometer box have something to do with shifting?

Mbbuff, thanks for your comment. I've got to have a 4th gear in there somewhere.