w124 e300 diesel vacuum modulator

[mjrose]

Does anyone know where its located? I'm refering to the modulator itself and not the pressure adjustment valve on the side of the gearbox.

I'm guessing its under the intake manifold somewhere but would like to know for sure before i take it off!

 

[SilverSaloon]

Does anyone know where its located? I'm refering to the modulator itself and not the pressure adjustment valve on the side of the gearbox.

I'm guessing its under the intake manifold somewhere but would like to know for sure before i take it off!

Hi

i have just adjusted mine - fixed my gearbox change flare...

anyway, its UNDER the car. You need to remove the plastic shield that covers the gearbox pan and then on the passenger side of the vehicle, look up at the side of the gearbox and you should see a little (white) cap. Prise it off with a flat bladed screwdriver and turn the key inside clockwise to make harder changes, or anticlockwise for softer changes, depending on what you need to achieve.

EDIT - just re-read your post - i believe the modulator is on the side of the gearbox. There is a black box under the crossover pipe that several vacuum pipes go to - maybe this is what you need

 

[mjrose]

Yes that sounds like it, thanks.

My local independant told me that the adjustor on the side of the gearbox is just a valve, and the modulator is actually in the engine bay and is attached to the throttle (i'm not sure how). But this enables the vacuum pressure to be adjusted to different throttle openings.

Mine is not working properly...

 

[SilverSaloon]

Yes that sounds like it, thanks.

My local independant told me that the adjustor on the side of the gearbox is just a valve, and the modulator is actually in the engine bay and is attached to the throttle (i'm not sure how). But this enables the vacuum pressure to be adjusted to different throttle openings.

Mine is not working properly...

The only adjustments that can be made (as far as i am aware) is the red cable at the top of the engine - adjusts when the gear changes happen. and the one on the side of the gearbox. Remove the cap, and there is a T piece that can be turned. I adjusted the T and sorted my gearbox problem. Not sure if there is any adjustment to be made on the one under the crossover as far as i remember.


http://www.mercedesshop.com/shopforum/attachment.php?attachmentid=57443&d=1216994274

 

[mjrose]

Apparently you can modify the pressure of the shifts with respect to the position of throttle by rotating the modulator itself. This link is from an ealier benz and with respect to a different issue, but i think you can get the idea:

http://dieselgiant.com/trannyleverreplace.htm

 

[Number_Cruncher]

>> I adjusted the T and sorted my gearbox problem.

More times than not, when people do this, what they are actually doing is covering up another fault in the vacuum system elsewhere.

Before twiddling with the modulator valve itself, check the vacuum system for leaks, and the correct placement and operation of both the in-line vacuum restrictors and the injector pump mounted, throttle actuated vacuum valve.

 

[mjrose]

>> the injector pump mounted, throttle actuated vacuum valve.

Thats the one i'm after. I have just had a look at lunch time and it looks like the vacuum can be altered at this location by altering the position of the down connecting strut from the rotating throttle mount.

 

[SilverSaloon]

>> I adjusted the T and sorted my gearbox problem.

More times than not, when people do this, what they are actually doing is covering up another fault in the vacuum system elsewhere.

Before twiddling with the modulator valve itself, check the vacuum system for leaks, and the correct placement and operation of both the in-line vacuum restrictors and the injector pump mounted, throttle actuated vacuum valve.

There was no vacuum leaks - after adjusting all the cables as per the pdf you emailed me a while back, adjusting the T slightly sorted the issue for me and all the gearchanges are silky smooth now