Hi folks. I am brand new to the forum and I am impressed!
Sam, looks you "da-man". Rather than go through 40 pages of posts my question hopefully is quick. I by-passed the EGR and took care of the harsh 1-2 shift. Vac. at idle is 12"Hg. 0" Hg at full throttle. Some flaring at 2-3 with vacuum in the 4-5" Hg range. What is/are the target vacuum ranges for the intermediate shifts.
Heading down to the MB dealership for the orifices now.
Again, thanks for this great thread!

Please tell us what kind of a car you have.

And special thanks goes out to...
 

Yes, I read all 40 pages of information (and misinformation.)

The upshot is that with your help, Sam, Brian, Dan, I now have in my 300SD 83Fed, a tranny with 272K shifting quite nicely.:D

I adjusted the vac at the VCV (9.5"Hg), replaced the rubber modulator cap/cover and most of the t's and orifices, connecting hoses, and took up some (not all) the slack in the bowden<?SP> cable. Shifts are now (mid throttle) 1.) about 2500 2.) about 3000 3.) about 4000 4.) about 3500. Trans Switchover valves and EGR seem to be functioning nicely as well, getting about 28+ in the city.

Plenty of pull, my 0-60mph is just under 18sec.

Next job: Timing chain, front brakes...

Welcome to the forum.

If it's flaring on 2-3 with 5" vacuum, you could try to reduce vacuum at idle to 8" and see how it goes. It might cure the flare if it's not too bad.

Hi folks,
The MB I have: '83 300SD 142K Mi Chassis W126 Engine: 617.95 Tranny: 722.3.
I have performed a full system leak test -- it holds vacuum well, about 0.2" Hg loss in ten minutes. The flaring at 2-3, which is not too bad, is occurring at ~5" Hg when acceleration is gradual. If I push the acceleration such that vacuum is less than 2" Hg, no flaring. It appears I am missing the first orifice (#62 on the vacuum line schematic) -- does anybody know what orifice size this is suppose to be?
Now, if I have plugged off the EGR valve, do the 3-2 valves now have a purpose? Looking at the vacuum diagram, I should by-pass them as well and avoid a potential source of leaks. No?
FYI, according to my MB dealership, the following orifices are no longer available in North America:
Red, 1.1 mm, PN 1162761029
Brown, 0.9mm PN 1162761429
White, 0.8mm PN 1162761229
This is my first exposure to the diesel engine -- loving it!

Wot
 

Are those the shift RPM's at WOT?

floydla1 - I will respond by editing your quote below...
 

Regards,

The needle valve is a GREAT idea! While reading your post I am slapping myself -- why didn't I think of that!

Your orifice is in place and functioning properly. You can't find it because it's just a small round sliver of plastic between two rubber vacuum lines. If any dirt has accumulated, it's effectively invisible.

The first thing to do is to remove the 3-2 valves from that system. They only serve to run the EGR. Here is how to eliminate them:

http://www.peachparts.com/shopforum/1375506-post5.html

After you remove the 3-2 valves, get a reading on the vacuum levels at idle and as you drive it. It's possible the flaring will increase. If so, report back and I'll show you what to do with it.

The needle valve is an addition that is not required for your vehicle. All adjustments can be accomplished with the existing systems on the vehicle. Those adding a needle valve have a non-functional VCV and they don't want to replace it because it's costly.

Hello Brian -- reporting back.

Sorry for the response delay. Yesterday being Valentine's, I thought it best to spend quality time with my girlfriend.

So, this evening I quickly isolated the black box and plugged the tees with golf-tees (I'll clean it up later). Vacuum at idle (~700 rpm) increased slightly to 12.5" Hg. At 50-60 mph the vacuum is between 7.5" Hg and 8.0" Hg. If I gradually accelerate from a stop such that the vacuum stays 4" Hg or above, there is flaring at 2-3, but I can not say that it is any worse that before isolating the 3-2 valves. If I accelerate such that vacuum stays below 3.5" Hg, shifting is smooth through all gears. No problems downshifting on full throttle. Whatcha think?

Agreed.........I did the same.........


Good job on the tests. What you need to do is to find the small dome on the side of the VCV and carefully lift it off with a sharp knife. Beneath the dome should be a small screw secured by a locknut.

Before making any adjustments, disconnect the main vacuum supply line from the T above the VCV and connect the Mityvac to this hose. It'll be the Mityvac on one side, the transmission modulator on the opposite side and the VCV on the bull (via the damper). Pump up the mityvac and confirm the 12.5" at idle. It should hold vacuum reasonably well..........bleed down in 20 seconds or more.

With the Mityvac pumped up (you'll have to keep squeezing if it's falling), release the locknut and turn the adjusting screw about five degrees (clockwise.......IIRC........but, it's been awhile). DO NOT TURN MORE THAN FIVE DEGREES. Watch the Mityvac and look for a reduction in vacuum down from the original 12.5". Keep pumping the Mityvac during this process. If I'm wrong in the direction of the screw......turn it very slightly counter-clockwise.

The goal is to reduce the vacuum at idle to approx. 8". If you achieve this, tighten the locknut, replace the domed cover, remove the Mityvac, and reconnect the main vacuum line.

Take it for a test drive. The 2-3 flare should be gone.

Report back with result.

You're right. That is WOT, not Mid-throttle like I wrote. They're rough observations...

Aside from 1/2 (about 3000) All my reg. cruising shifts are between 2000 and 2500 or so.

Sure is behaving a lot better, though.

Hello Brian,

Reporting back. I confirmed that there was no orifice in the tee to the VCV / modulator, so I waited to make adjustments to VCV until I got the orifices from the MB dealership. I put the smallest orifice in, but the vacuum was still in the 12.5 - 13.0"Hg range at idle. The adjustment on my VCV is not a screw / locknut, but just a 9mm nut. Adjusted vacuum to 8.1" Hg at idle. 1-2 shift is firm, flaring at 2-3 is gone, 3-4 smooth. Lookin good! Thanks. Now, on to the oil cooler hoses!

Interesting...........the addition of the orifice didn't make much of a difference. Certain people are going to be shocked by that revelation..............

Based upon your original readings, I'm a bit surprised that no orifice was present...........the vacuum levels were quite normal.