1980 vacuum routing
 

Hi folks, I am looking for input from other 1980 w123 300d/td/cd owners on whether this vacuum diagram reflects the reality of how their cars' vacuum lines are connected up.

Background: this discussion began with another thread that concerned my 1980 300td tranny that won't upshift from second. I've had a short crash course in the wonders of the 1980-only, vacuum-control-only transmission.

In any case, I found this 1980 vacuum diagram through a link in a sticky thread here. It's from the Peter Schmid Transmissions site.

As I see it, it does NOT reflect the reality of how the vacuum on my car is currently plumbed. I'd like to get input from others....

Thx

BUMP; surely someone out there has an '80 in their driveway :rolleyes:

Yeah, that's how I remember mine looking on the 1980 300TD.

I've ripped it all out since I swapped transmissions.

KenB

Mine's an 81, but that doesn't look familiar. (Sort of, but not totally). I'm subscribing to your post, because I'm having the same problem as of a few days ago.

Could you post pics of your set up?

Well ;
 

I have a 1980 30CD and it's like this , when it stopped up shifting into 4th gear I chased all the leaky rubber hose bits before it gave up entirely , I drove it (slowly) in 3rd. gear to my indy Merz guy who adjusted first the 3/4 band on the tranny (threads on this about here) then he re-adjusted the valve on the IP and it began shifting again , as it leaks a tiny bit and doesn't bang through the gears like my 300CD does I'm not 100 % happy but it does work O.K. when connected like this and adjusted to the vacuum drops off to _zero_ as you depress the throttle .

It's been several years now and many many long distance trps over mountains etc. fully loaded down with 5 adlts & luggage and shifts the same...

I hope this helps .

longtime 1980 owner
 

I had a poor shift problem for a very long time in my 1980.
Everything you said about the only-on-1980 vacuum controlled trans is true.

My problem ended up being a leaky 2/3 valve on the valve cover that controls the vacuum.

Until this forum, and ten years of poor shifting, I did not figure this out.

After replacing the trans, and the problem persisted I got serious and tracked down this little valve.

I now own spares and several little lever/arms bought here from fastlane.

On my 1983 I ditched/removed the 2/3 valves completely, but not on the 1980.
Also, getting enough vacuum to the trans. Moving the line closer and closer
to the pump on the main feedline to get stronger vacuum.

My 1980 now shifts beautifully.

I hope I understood your problem correctly and made sense.

If it turns out you need a good 3/2 valve, I've got a good working one I can sell you for a song.

KenB

Pics
 

Here you go... hope you can make out the routing....

If I am understanding the diagram correctly, the tranny is taking its vacuum from a looped line that runs to the 2/3 switch and then on to the tranny. The third port of the switch is capped. The line on the other side of the switch goes to the vacuum control valve.

On my car, the orfice showing capped in the diagram is the one getting the feed off the main line. The line beside it (black) goes to the tranny. The other side (red/black) goes to the VCV.

Nice pictures. I will take some tomorrow morning of my 1980 valve cover so
you can see. The car shifts great so I consider it proper.

If you have to remove one of the lines we need to figure out why it is there
and re-route or plug as needed.

Now, another thing is, do you have the vacuum pump tool for testing the existing valve ? To see if it leaks.
It may not leak at all. But it helps to know.

They do not cost much. (the 2/3 valve or the tool....).

Anyway, get to you in the morning.

My last thought is that a station wagon 1980 may have some reason for that line being on the valve.
But I hope not as it will make this easier.

This is the closest set up I can find, hopefully, it'll help.

I have an 80 td parts car that's unmolested so far. lemme know if you need anything pics or parts...

also, I notice you have a vacuum line off in one of your pictures. the yellow ball looking part near the firewall has a hose off...

Thanks for the info about the parts car.... I did notice that line off after I took the pic :o

Okay I HAVE TO ASK, exactly how many vacuum layouts was it necessary to have?

This almost looks like rearranging the vac lines each model year was the running joke in the Engineering Dept....

Your diagram looks absolutely inexplicable to me. Is it from an '80???

Thanks for the input everyone.