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/showpost.php?p=1375506&postcount=5

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.

I thought the 3/2 valve had something to do with transmission shift also? Not true? As I recall, Dieselgiant's site has a procedure to replace the 3/2 valve to restore proper shifting? Curious why it is called the 3/2 valve. I still have mine. Going to get rid of it now.

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85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

It depends on the vehicle. My comments are vehicle specific. You can remove the valves on the 300D turbo.........not on the 240.

Thanks Brian. Can you explain why?

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85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

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

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Larry in Mobile, AL
'83 300SD "Goldfinger" 145K Mi W126 E-617.95 T-722.3 15" Bundts

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?

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Larry in Mobile, AL
'83 300SD "Goldfinger" 145K Mi W126 E-617.95 T-722.3 15" Bundts

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.

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!

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Larry in Mobile, AL
'83 300SD "Goldfinger" 145K Mi W126 E-617.95 T-722.3 15" Bundts

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.

Maybe there was an orifice of dirt at the T on the main vacuum line. It one time, I had very hard shifts because I had no vacuum to the tranny. Problem was total blockage of the T at the main vacuum line. Could partial blockage at this point have the same effect as an orifice?

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Charles
1983 300D, bought new, 215k+ miles, donated to Purple Hearts veterans charity but I have parts for sale: http://www.peachparts.com/shopforum/showthread.php?t=296386

Brian I am having trouble with my 81 300SD. The problem I am having is a kinda slow shift from 2-3 under heavy throt. and worse flaring when its shifting from 3-4. It seems to shift fine though when not under heavy acceleration. This all seemed to happen overnight, as the day before it shifted great until I went through water over the roadway.

Ideas?

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Regards,
Ian White

1995 E300 Diesel w124 OM606
2014 E550 w212 M278 biturbo

2001 BMW 740i E38 M62 (past)
1981 300SD w126 OM617 (past)

Cannot tell anything until you hook up a vacuum gauge to the modulator line and advise what you've got.

Read the gauge at idle and at various pedal positions while you drive it.

Brian,

Was driving on a main highway for about an hour at 70, entered the city and slowed to make a right turn. When accelerating(gently!) out of the turn, I heard/felt a clunk, a bang and it just flared like crazy. I could get it to move only if I revved to 3500-4000 rpm and then backed off a bit. It then slowly gathered speed enough to make it home(about 70 miles). Vacuum is good to the modulator, and the VCV leaks off from 12" to 5" in about 20-30 seconds. When I checked the fluid right after it happened(before returning home), it was 1/2" high on the dipstick and had some small bubbles. After returning home and letting things cool for a day, the fluid was where it should be and the color looked ok(red not brown). Also discinnected the vacuum line to the tranny and it seemed to move a little better, although still flaring badly. Ordered 2 AT filter kits yesterday and will change fluid/filter, add Trans-X, run engine for an hour or so, drain and change filter, fill with AutoZone Dexron III/mercon(only kind available locally) and hope for the best.
Question: Should I also try to get the K-1 and K-2 kits and install them at this time? If so, what are the p/n's for them. Thanks for any advice as the closest M-B dealer is in Tucson(500 mile round trip). I really hope that there is a solution other than a rebuilt tranny.

PS, haven't pulled pan yet to see if any strange pieces down there as only place to work is open to the wind and dust(it's Mexico) and when I do open it up, I will need to make some kind of wind/dust barrier.

Dave
'81 300SD
'81 VW diesel caddy

Car in my previous post with tranny problem is a '81 300 SD with 187k miles. Tranny is 722.303 02, s/n 073124 and is original trans(I think). Car was purchased 3 years ago with 153k miles. No idea who previous owner was as it had been a church donation for charity/fund raising sale.

Sorry 'bout that.....Dave