What problems might this be causing? (Broken Transmission Vaccum Valve) - PeachParts Mercedes-Benz Forum

chetwesley · #1 04-04-2007, 01:50 PM

I was just looking into some problems I am having with shifting in my 300TDT (you have heard it before -- hard shift 1-2, "flaring" 2-3, a little hard (but ok in my opinion) from 3-4).

I am looking into the possible solutions that a) I can do myself and b) don't cost more than the car cost me.

Searching the forums, I came across a thread with a link to an article for replacing the transmission vacuum valve levers...

http://www.dieselgiant.com/trannyleverreplace.htm

So I went out to look at the levers on my transmission vacuum valve, and I discovered that not only were they worn. The top one is actually missing altogether! It appears to be broken off, and the top hinge on the lower one is broken as well, but the lever is still there. The cover to the "box" is missing as well, but I assume that doesn't have any funtional purpose (except perhaps to prevent damage like this).

In addition, comparing my TVV to the one in the article, there are two hoses which are missing. Does anyone know where these two hoses are supposed to lead? (see pic) By the way, the first missing hose is obvious, but the second one is hidden in the back (lower back left in the pic)

I am new to auto repair in general, though I am not afraid of it (why I'm here), and this seems like a simple enough fix. So, could this be the cause of my problems (or a start at least?)

thanks
-Chet

chetwesley · #2 04-04-2007, 01:51 PM

whoops, forgot the pic...

rrgrassi · #3 04-04-2007, 02:53 PM

Is yours a turbo model? IIRC on a N/A engine it has one of those valves, not two. I could be wrong though.

On the turbo engines you can easily by pass and disconnect those lines.

chetwesley · #4 04-04-2007, 03:31 PM

Yes, it is a turbo... I am sorry, what is a N/A engine?

Quote:

IIRC on a N/A engine it has one of those valves, not two.

So does that mean that it is supposed to be missing those two hoses?

Quote:

On the turbo engines you can easily by pass and disconnect those lines.

So does that mean that it shouldn't be causing these problems, or does it mean that if I bypass it, I might be able to bypass the shifting problems as well.

Thanks for the help for this slooow poke.

Phil · #5 04-04-2007, 03:37 PM

I posted a picture of those valves the way they are on my car on this thread. Look at # 4.

http://www.peachparts.com/shopforum/showthread.php?t=177371

As I remember some ports on the valves are vented but I doen't remember which ones. Mine had levers like yours when I got the car so I replaced them.

chetwesley · #6 04-04-2007, 04:03 PM

Thanks for the link.

Well, my levers are more than worn... I think if I wanted to get this functioning properly, I would have to replace the whole unit. It looks like the upper valve would be going to the lower middle of the black thingie on the left (off to the left out of my pic), and the lower (unseen in the back of my pic) should be going to the lower corner one... however, those are then not connected to anything else (see attached pic). They appear not to be on yours either. So it is fine that they are left open on the transmission vacuum valve?

Is it worth it to replace it? It seems some people have bypassed it alltogether.

I don't really understand what it does. Is it related to the EGR valve? (something else I don't know what it does, but I have heard of people bypassing this as well).

Excuse the ignorance...

rrgrassi · #7 04-04-2007, 04:03 PM

Quote:

Originally Posted by chetwesley

Yes, it is a turbo... I am sorry, what is a N/A engine?

So does that mean that it is supposed to be missing those two hoses?

So does that mean that it shouldn't be causing these problems, or does it mean that if I bypass it, I might be able to bypass the shifting problems as well.

Thanks for the help for this slooow poke.

N/A normally aspirated, or non turbo.

No, it should not be missing those hoses. But if you bypass the assembley, then it will not matter if the hoses are missing or not.

Brian explains how to by pass the 3-2 valves on the top, and effectively disable the useless EGR.

There is a ton of info in a thread started by Samuel Ross caleed something like It's important to know how adjust your transmission...

I followed what Brian said and by passed the 3-2 valves and EGR. That ended the under the hood vacuum leaks.

chetwesley · #8 04-04-2007, 04:16 PM

I think I found the thread you are refering to. Here it is for any future searchers.

http://www.peachparts.com/shopforum/showthread.php?t=158216

chetwesley · #9 04-04-2007, 04:33 PM

Ok, this may be the last quesiton I have to ask...

In post #44 http://www.peachparts.com/shopforum/showpost.php?p=1257488&postcount=44

Brian explains how to bypass these parts, and refers to the diagram in post #42, which is for a 82 300D
http://www.peachparts.com/shopforum/showpost.php?p=1257474&postcount=42

As far as I can tell, this appears to be the same setup as my 81 300TD turbo.

Can anyone confirm or deny this?

Sorry, I am being a little cautious about this because I need to drive this thing to get to work everyday

Thanks a bunch.

-Chet

rrgrassi · #10 04-04-2007, 04:41 PM

What was the MFG date on your car? IIRC 1982 was the first year for the turbo in a w123. The PO could have installed a turbo engine.

You have the exect same setup I have. Except I have the sedan. The bypassing took all of 5 minutes.

It looks like the transmission hook up was bypassed, but the EGR portion was not. You can disconnect the EGR lines and plug the open vacuum port.

I'm cautious as well. First MB, and it's a daily driver also. I do have a truck a back up when needed.

chetwesley · #11 04-04-2007, 04:54 PM

Thanks. Hmmm... I am pretty sure it is 81, and I seem to recall seeing many other 1981 300TD turbos around. It has the "turbo diesel" tag on the back of the car, so I am pretty sure it came with the turbo, unless they added that too when they put in the turbo engine

One thing I am seeing is that this fix seems to help with hard shifts, but my main problem is a soft shift ("flaring") between 2-3. Well, I will give it a shot anyway.

rrgrassi · #12 04-04-2007, 05:16 PM

Quote:

Originally Posted by chetwesley

Thanks. Hmmm... I am pretty sure it is 81, and I seem to recall seeing many other 1981 300TD turbos around. It has the "turbo diesel" tag on the back of the car, so I am pretty sure it came with the turbo, unless they added that too when they put in the turbo engine

One thing I am seeing is that this fix seems to help with hard shifts, but my main problem is a soft shift ("flaring") between 2-3. Well, I will give it a shot anyway.

TD is for the wagon. The T means Touring. That is why you will see people put TDT for a wagon also to indicate it's a turbo. The SD sedans (w116 and w126) were turboed before the w123.

How bad is the flairing between 2-3? I have to replace the K-1 spring in my tranny. Adjusting the bowden cable has helped a bit though.

My car was made in Oct 81 and classed as an '82.

Phil · #13 04-04-2007, 05:32 PM

Quote:

Originally Posted by chetwesley

Thanks for the link.

Well, my levers are more than worn... I think if I wanted to get this functioning properly, I would have to replace the whole unit. It looks like the upper valve would be going to the lower middle of the black thingie on the left (off to the left out of my pic), and the lower (unseen in the back of my pic) should be going to the lower corner one... however, those are then not connected to anything else (see attached pic). They appear not to be on yours either. So it is fine that they are left open on the transmission vacuum valve?

Is it worth it to replace it? It seems some people have bypassed it alltogether.

I don't really understand what it does. Is it related to the EGR valve? (something else I don't know what it does, but I have heard of people bypassing this as well).

Excuse the ignorance...

Those valves are probably ok. I would replace the levers if your state has a smog inspection because then they probably look to see if everything is there.
You can always test the EGR by putting a BB in the vacumn line to it as that disables it

The flare in the 2-3 shift can usually be corrected by replacing the K-1 spring kit in the transmission and adjusting vacumn bleed.

DeliveryValve · #14 04-04-2007, 06:06 PM

Quote:

Originally Posted by rrgrassi

TD is for the wagon. The T means Touring. That is why you will see people put TDT for a wagon also to indicate it's a turbo. The SD sedans (w116 and w126) were turboed before the w123.

How bad is the flairing between 2-3? I have to replace the K-1 spring in my tranny. Adjusting the bowden cable has helped a bit though.

My car was made in Oct 81 and classed as an '82.

In 1981, the 300 "TD" (wagon) in fact came in with a Turbo Diesel. The sedan was NA.

I would just remove the two lines going to the black box and plug up the other ends. (but make sure you can do this per state regulations with the EGR as stated in the post above) This will definitely help with the vacuum problems.

rrgrassi · #15 04-04-2007, 06:11 PM

Quote:

Originally Posted by rmarzan

In 1981, the 300 "TD" (wagon) in fact came in with a Turbo Diesel. The sedan was NA.

I would just remove the two lines going to the black box and plug up the other ends. (but make sure you can do this per state regulations with the EGR as stated in the post above) This will definitely help with the vacuum problems.

Learn something new...that dispells the thoughts that the turbo w123 models were a 1982 intro.

Either way, the 3-2 valves you have are set up the same as the 82 and up, except for 1985 California models, IIRC.