84 300sd Trani help
 

Calling all trani experts!
The shifts in all gears especially 3-4 are sort of soft and the 3-4 seems to sort of hesitate in the shift.
When backing up quickly or backing up a steep hill the trani will slip and grab then slip and grab again. Backing up on level ground in no hurry is ok.
Is this a sign of low pressure?
Is the pressure adjusted with that green thing on the drivers side?
Boden cable and vacuum are good.
Thanks

Low on fluid?
When was the fluid last changed?
May need to adjust trans fluid pressure.
You need to access a copy of the trans manual and have a read.

Thanks for getting back to me.
Fluid is only 6 months old.
How is the pressure set?
Can I access a manual on line?
Thanks

You really need to tune the vacuum system to firm up the shifts on the SD. The stock settings are way too soft for most of us.

There's plenty of info in the archives about that adjustment, provided that you've got a Mityvac.

After you've done suitable research, you can repost on this thread and I'll help you with it if you get stuck.

Additionally, the 300 turbo benefits from the elimination of all lines to and from the black box. This is also detailed in the archives by me.

Thanks Brian and members
I will do as you suggest,but the black box I think must remain in service as we have a thing called Air Care we have to pass every year. It is a particulate count of the exhaust while driving at 70 kmh on a set of rollers. Afraid to upset the system.
Thanks all.

See if you can determine if the measuring equipment simply samples for "particulate count" or if it has the capability of measuring "NOx" emissions.

Removal of the EGR system will only effect the NOx output.

Well Brian. I replaced the vacuum control device, the one on the car was not venting. With the new one installed the Gage reads 15 and will go very close to 0 with the pedal on the floor.
The shift from 1=2 and 2-3 is now firm and smooth. The 3-4 shift just slams in. a real drive shaft bender. The 3-4 shift was soft and hesitant before with no vacuum. I think the "European Auto Specialist" had no
Idea what to do with a Mercedes diesel and just played with everything. The cap was off the original vacuum control valve and the spring was undone from the shaft. Is there a possibility they adjusted the modulator to compensate for the lack of vacuum control.
Thanks for your help Brian, much appreciated.

With 15" of vacuum and light pedal pressure, the shifts should be butter smooth.

If they are "firm" and the 3-4 is harsh, I'd venture a guess that the shop might have raised the modulator pressure.

Ask them outright............"Did you adjust the modulator?"

We'll go from there.

Thanks Brian.
I will reduce the modulator pressure a little at a time. Let you know the results.

Hi Brian.
I got under the car today and turned the little "T" key almost two turns.
I did this 1/2 turn at a time and could feel the shift get better with each adjustment. What a great feeling to know I just saved the price of a rebuild. The problem with the slipping reverse also corrected.
When I removed the cap and pulled the T key out it came right out in my pliers. I wasn't expecting that. Almost did my coveralls in. Is that the way they all are?
Thank again for your assistance Brian. What a fantastic board this is.

While I have you on the line, is there a way to adjust the governor on the IP. When I go to drive the revs drop from 750 to 500.
When the AC comes on the engine almost stalls. Acts like no governor at all.

I am not aware of any external adjustment that can be made to get the governor to behave. The symptoms suggest that the flyweights are not working properly...........or at all.

Thanks again Brian. I will look at swapping the IP.

As a side note regarding the governor, the '86 SDL began acting up after sitting for a couple of months. It would begin to hunt badly for an idle and would just about stall each time it headed down.

Did this for about 10 miles until it got a full tank of fuel and then continued to do it to a lesser degree until it ran for another 40 highway miles, which appeared to cure the issue.

Therefore, something affects the pumps when they sit too long...........the cause of which is elusive to me at this point.

The car has been on Synthetic motor oil for some time. Is there an additive that I can to the oil that may free up the weights?