Fabien92

Correct. It’s the situation with the vacuum line connected.

We have not checked the level of vacuum. We will do it 😉

UPDATE : After a drive test this morning, at cold, it's really better !! It slips again before to shift in 3, from 2100 to 2700 RPM. The shift in 3 is always a little bit hard, but it's better.
We will take vacuum on both engine and transmission sides as soon as possible.

Schocki

Slow progress but good progress. Turn the vacuum modulator one more full turn clockwise and report back if this improves the slipping at all.

Fabien92

Hi Shocki !

We will measure vacuum on tomorrow at 12:00 AM (it’s 6:45 PM).

About modulator. I will turn it 😉
But on saturday we had 4.6 bars. I turned 1/2 anti clockwise to be at 4.4 bars, but I didn’t measured it after that.

A new modulator is on the way from France !! With 3 caps in case of 😂

About vacuum. How do you measure it ? Is it ok on the lift with idle engine ?

Schocki

Checking the vacuum on the lift while the engine is running is just fine. Make sure you measure the level of vacuum at the front damper first to have a reference when you check at the transmission.

Fabien92

Hi Shocki,

Well done !!! We have vacuum in D (pressures dampers) and in E (pressure regulator). --> We have repaired the vacuum line from the MAF to the 5 ways splitter.
But nothing on transmission side !!! --> The line is cut off somewhere !!

On next saturday, we will change the vacuum line from the 5 ways splitter on the engine side to the modulation valve on the transmission side !!! I think to add a new line without removing the old one.

I am so confused. Two days ago I said it was better ... But it's not possible !! It was a bad feeling !!

Schocki

Hello Fabien,

Again slow progress and another small issue encountered.
Looks like your 5-way splitter is fine. At least the fuel system is happier now.
Check the vacuum outlet at the splitter directly for the automatic first before you dig into the issue. Sometimes the splitter cracks and causes issues too or the house from the manifold sits to deep in the splitter, closing of vacuum supply. Make sure that there is vacuum provided at the splitter first.
The vacuum line is a metal tube tied to the torque tube, connected at the front and rear with a flexible hose. Check the rear first, the center mufflers have to be removed as well as the heat shields.
Good luck!

FredR

The vacuum line is a composite thing consisting of nylon tubing, hose connectors, steel tubing [along the side of the torque tube] and a section of vacuum hose to connect to the modulator. The line could be disconnected or blocked and is a common "age related" failure point.

Fabien92

Merci Shocki

We will follow all your instructions, slowly and step by step

Schocki

Fabien,

We have a saying in German: "Mühsam ernährt sich das Eichhörnchen" or "Squirrels feed themselves laboriously / Squirrels have a hard time feeding themselves".
I hope you don't feel like a squirrel after your ordeal began, I admire your patience. This feels like a true test how much you like your GTS.
After all your 1st post started with "Happy New Year..."

The metal tube fixed to the torque tube is most of the time ok. The aging rubber hose at the end to the automatic is often in bad shape. The factory never bothered to secure vacuum hoses and connectors with cable zip ties. why? Because vacuum holds everything together, right? I highly recommend that you zip tie the line this time in order to prevent future headaches. Always remember WYAIT with our cars.

As soon as there is vacuum supplied to the modulator in the back, you should feel a significant (certainly noticeable) improvement in shift quality. It's like new motor mounts or Bilstein shocks. You never knew what you've been missing all the years until you change them. The MB tranny shifts very smoothly, not like a modern 8-speed unit but good enough to give you a good GT feeling.
Due to the high engine torque and effectively 3 gears only, you can always feel the shift. But the upshift should be quickly but smooth too.

Stay positive and it'll be all fine in the end.

Fabien92

Since my happy new year, I was always positive with a lot of patience. 😊

I learn a lot about my GTS, with very good friends to help me here in New Caledonia, or on RENNLIST 😉

Since 8 months we did a lot, by ourself. I never went to the tranny shop with a suitcase of dollars 😂😂 I spent time, but only 1500 USD.

I hope an happy end very soon 😊

Geo55

I lost the rubber vacuum line that went from the engine compartment to the bell housing and attached to the metal tube there. Not to bad to get to, just remove the metal shield on the passenger side front. Wish I took a picture to show.

Fabien92

Hi George,

Thank you very much Easy to check, if you have your picture to help me

belgiumbarry

the more i follow this thread , the more i like my manual box...sorry , couldn't resist .

Schocki

Wait until the day comes when you need parts for your transmission. The 722.3 from MB was produced in big numbers and parts are readily available.

Fabien92

And my transmission never failed until a « friend » drove my 928 and broke it ... 🤬 F@&cking ex friend 🤬