Hey Guys, so still trying to chase down a hard shifting issue. Even standing still, shifting from reverse to neutral I get a loud thunk in the rear. Replaced the flex disks which I thought would help but now looks like I need to do the differential bushings as well...

As I'm checking vacuum, strange things are happening. I get 20+hg out of the pump consistently, and 15hg out of the BFS, but not consistently. I pulled the VCV (which is only a year old) to reset it and noticed some black oil inside the housing where the angled pin is. Does that mean it's leaking or no longer sealing properly? I generally test vacuum at the source and at both green dampeners, the VCV port sometimes shows vacuum sometimes virtually nothing. I don't get it, any help appreciated.

__________________
1987 300td 240k #14 head

Check and see if you have Oil in the Fuel Injection Pump Vacuum Shutoff Line.

Vacuum Adjustments only solve the hare shifting issue some of the time due issues inside of the Transmission.
The Vacuum Adjustment is the first place to start and if that does not help check the Pump and Modulation Pressure.

Transmission Vacuum and adjustments
http://www.continentalimports.com/ser_ic20242.html

__________________
84 300D, 82 Volvo 244Gl Diesel

That's a great write up, thanks for the link. I think I've been adjusting the right things and think I found the problem. The mechanic who put in the flex disks hooked up the center line from the BFS to the tranny as opposed to the off center line. I've corrected that and it's better.

I'm not sure I know the IP vac line you're referring to, I do get oil in the lines top and bottom of the switch-over valve (Y30). Would that contribute to oil getting in the VCV?

__________________
1987 300td 240k #14 head

Okay I think I found the vac line you're referring to, the one going to the center of the white round plastic thing atop the IP. I disconnected it but it's the original brown color so I can't tell by looking if there's oil in there. There's definitely oil ON the line...

The integrity of the line seems good as the shutoff lever functions as expected when running and when not.

__________________
1987 300td 240k #14 head

Have you killed the EGR and cleaned out the intake? Not a small to do I know.
The exhaust sludge is like a spreading cancer and boost pressure just forces it into your vacuum lines.

I've killed all vacuum to the EGR and everything else left of the block long ago. Everything that's no longer needed once the trap is gone. I do have the EGR blocking plate kit to get rid of it completely but haven't installed it yet, because it's been single digits for what feels like months in New York. I guess that's next...

__________________
1987 300td 240k #14 head

Yeah I hear you on the cold, something about touching 10 deg metal turns me off.

It's been a while since I removed most of my vacuum system. I was trying to explain the grease you found in your VCV and I thought there was a connection between the overboost pressure system (y29) and the vacuum system. There might not be.

Suffice to say any connection with anything and your intake could have sludge forced in.

At the end of the day, you should have around 11-15hg of vacuum to your transmission modulator and this vacuum should drop to zero as you press the accelerator.

Hi guys, if you allow me to jump in this thread, my 87 300SDL has some VAC gremlings that I cannot figure out. I read Steve Brotherthon's great article which taught me a lot. In my car, I get a steady 25"Hg VAC from the pump. My problem is the VAC in the line going to the Xmission. At idle, I measure the expected 12"Hg but when I rev up the VAC in the line increases to higher levels with the RPMs rather than dropping to 0. About the shifting, during the first 10 15 minutes of driving the shifting could not be any smoother. After that, if I am coasting and have to reduce the speed or come to a stop when I accelerate to get moving, the engine revs up but the 2nd gear does not engage (or if it does it is very abrupt and hard). Only if I let the RPMs come down to zero the gear engages and shifting is semi restored until the next slow down.
Any thoughts? Thanks in advance.

So vacuum to your transmission increases with rpms?? Never heard that one before, this doesn't cause extreme flaring? How much does the vacuum climb to?
There is a function that softens shifts when coolant is below 50c I believe. My car also shifts nicer when cold.

It pegs at 15"Hg and when I release the accelerator it comes back down . The lines are all hooked up in the right places, so I am wondering if something can make the Vac modulator malfunction and work backwards. I bought the car recently in an estate sale and I am trying to bring it back to glory.

Could be anything I guess. You could bypass the BFS etc. for troubleshooting. Just route pump vacuum directly to the VCV and out to the tranny from there.

I will try that. Thanks for the suggestion.

__________________
______________________________________
87 300SDL
92 300D 2.5 TD