1. Home
  2. Mercedes Autos and SUVs
  3. Vacuum to Transmission

Vacuum to Transmission

Does anybody know if the vacuum line to the transmission on a 1982

300TDT is ganged with the automatic locking branch of the vacuum system? I capped the line that goes to the locking system at the junction connection in front of the firewall.

My tranny has been shifting down hard into the bottom gear and someone said that was because the vacuum control was not functioning and now I think I may have disconnected that line too when I blocked the vacuum locks. Where I live I seldom have to lock the car, but I don't like the hard shift down which will eventually start to damage the drive line components. I may have to route a line especially for that control unit on the side of the tranny.

I have tried to fix the locks, but I can't seem to locate the leak. I think it must be in a line because the actuators in the doors, including the tail gate, all have been replaced and seem to be fine.

Any ideas?

Reply to
heav
Loading thread data ...

Vacuum are all tied into AC... tranny and others. On W123, I believe the lock also is tied to the engine vacuum... recalling how engine won't shut off with failing locking...

First, check the vacuum strength on your vacuum pump... Go to MB EPC and look up AC vaccum actuator part list... it will show you the entire vacuum diagram for AC... your car should have a vacuum bladder... which does go bad and cause problems for everything.

Basically in a nutshell, you got a big leak. somewhere. so trace them down from the vacuum pump.

Reply to
Tiger

I would recommend getting the vacuum trouble shooting guide from mercedessource.com. Here is a link to it:

formatting link
This gives you a pretty good overview of how the vacuum system works and what is connected to what. There is also a video somewhere on his website about tracing vacuum leaks. I love Kent's products. I get parts from other places sometimes, but the instructions that come with some things (along with custom tools) are definitely worth the extra price. Its usually not even that much more expensive. Highly recommended.

Reply to
DougS

Thanks. I notice immediately at the web site that he mentions hard shifting as one of the issues related to vacuum so I am pretty sure the vacuum issue is at the root of my hard shifting issue. I have the diagrams that come with the Mercedes manual so maybe I can proceed from there.

Reply to
heav

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.