Like the thread title states I want to replace the vacuum line but there are no threads I could find that would say how.

The reason for replacing it is that my vacuum modulator failed and I need to replace it so I though I may as well replace the old vacuum line while I was at it thinking it was as easy as in my 3 speed auto.

I was definitely wrong in that regard. It loops up and over the trans through a hole and connects to a hardline at the front of the trans. I saw this using a endoscope.

Does anyone have any tips or tricks to doing that that doesn't involve dropping the trans?

Thanks!

 

Git up there, hug it...realllly hug it.

Bill Ball can do it...I've seen it.

 

But my car weeps trans fluid like no tomorrow( drops never hit the ground). I guess I'm going to get real greasy

It's going to be fun explaining this at work lol. That forward most line is going to be a pain to get to in front of the trans where it connects to a hard line.

 

Here's a picture of replacing the vacuum line and running it in spare body clips. I did this too.

 

I have to ask why? The plastic vacuum lines last forever unless they are melted or mechanically damaged.

Use your handy vacuum pump to test it.
First, with both ends disconnected and "open to atmosphere", connect the pump and make sure that it can draw no vacuum on the line. This ensure it's not collapsed.
Second, plug one end, and use the pump to ensure that the line holds vacuum thus ensuring that the line has no leaks.

 

The one that runs on top of the trans is cloth covered rubber. The ends crack and leak typically. Mine was no exception.

I figured I may as well replace it as I have the correct hose on hand because I don't want to have to drop the exhaust again.

 

I finally got the line on, but the front part of the line that connects to the hard line was a major PITA. The rest was an absolute breeze.

I just cut some cloth covered vacuum line using the old one as a template and put the protective rubber covers over the parts that were covered on the original and did the hard line end first so it had as much slack as possible to work with.

It's one of those fun things where you can see it, but you can't actually reach it with your hands unless you have small hands with very long strong fingers. Fortunately it wasn't around a bunch of sharp metal.

I had to get this to even get close to getting it on https://www.homedepot.com/p/Crescent...200C/204064450

I then fished the line through the hole in the trans by feel and put it next to the vacuum modulator. I have one on order from my local Mercedes dealer, figuring their stock is fresher than Porsche's.

It also cost $51 compared to the same part from my local Porsche dealer costing over $75 and it will be here tomorrow. Porsche classic really needs to learn a few things from Mercedes....

 

Right, I was thinking the front line. The cloth part of the line is accessible with the heat shields off. The plastic vac line at the front is the PITA.

 

Agreed.
I replaced the plastic line on the front on the Red Witch the first time with desperation, new curse words, broken wrist type dexterity, and two pairs of extended reach needle nose pliers.

 

You will need to adjust the modulator pressure. I bought this a couple of years ago. Mercedes Transmission Vacuum Test Kit

 

On my to-do list

 

IMHO, abandon the plastic tubing over the TT and run metal brake line down the DS.

 

Kevin:

Every single time I get a car in with the transmission line routed down the outside of the tunnel, I flinch and swear at the guy that did this, instead of fixing it the right way....

The stock line is routed so that it goes downhill the entire distance, so if the modulator goes bad, the transmission won't get sucked dry, as quickly.

 

I am not sure I understand what you are saying.

 

One of the failure modes of the modulator is to leak trans fluid into the vacuum line causing blue smoke out of the exhaust.

It can literally suck the trans nearly dry of ATF. Not a fun thing to have happen.