Brian - After reading your post, I was reviewing all that I have done to the coupe recently, in regards to the transmission shifting adjustments. It occurred to me that I had adjusted the modulator a total of 3.5 turns, and the flaring did stop, but I had hard - jerky shifts, with the pronounced clunk when the trans shifts down from 2nd to 1st when coming to a stop.

I went back out last night and connected my vacuum gauge and found I had very little vacuum at the modulator line from the green dashpot. So I direct connected the hand vac pump and could not get vacuum to stay steady in the least. The vacuum would drop between pumps.

I then disconnected the vac line to the modulator at the trans and blocked the line, Better vacuum but still fell to quickly. I replaced the rubber hose connector at the end of the modulator vac line, blocked it and it was much better, so I reconnected it to the modulator and re-tested. Now it fell drastically again. (By now I am scratching my head, it's 9:45 and dark)

I set up the flood lamp, crawled under her to check that the cap was on the modulator properly and it was. I removed it, cleaned the modulator groove that the cap grabs, reinstalled & tested again. Still fell drastically. I inspected the modulator cap and observed very fine cracks around the outside of the sealing edge. This very likely is due to age I suppose. Then, I had an inspiration. I cut the tips off of the pinky finger of 2 latex gloves and put then on my pinky finger. Then I placed the modulator cap on top of the latex pinky tips, rolled the pinky tips over the modulator cap edge, and then reinstalled it carefully on the modulator.

A re-test gave me excellent results with the hand vac pump. I reinstalled all the vac lines as they were when I started. I got a vac reading of 12 to 13 at idle and drops steadily to zero while opening the throttle. (I need to look into the throttle linkage and lube, it seems a bit "tight")

At this point I had to button her up for the night. By now it was 10:30 PM and I had to get some sleep.

Drive test was excellent today on the way into work, just a very minor "clink" sound at the rear left wheel. Then I tried only using one foot to drive with. (I always have driven with 2 feet) This keeps my foot off the throttle when coming to a stop, thus allowing the vacuum to rise fully and now EVEN THE "CLINK" IS GONE. I am VERY pleased with the drivability of the transmission now.

On a side note, the cruise control is sporadically functioning now. I plan to check my ground circuit to the cruise amp first as when it does function, it functions properly.

Thank you for all of your help with this, I do appreciate it.

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1983 Mercedes 300CD Turbo- 199,370 miles - Lapis Blau
1974 Mercedes 240D - 186,445 miles - Aqua Blau
1982 Volvo 244GL Diesel wagon - 168,956 miles - to be sold
1994 Chevy G30 6.5 Diesel "short bus" converted for camping, painted red white & blue & white stars 78,956 miles
JD F935 diesel front mower

That's a good job in troubleshooting. I'd replace that rubber cap at the earliest opportunity.

With proper vacuum modulation, you've got no flaring.........and no clunking...........just as it should be.

I did send an email to my local dealer to get a price on the cap, I found this part number, A 126 277 00 81, on EPC. Should have an answer tomorrow.

Again, thanks very much.

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1983 Mercedes 300CD Turbo- 199,370 miles - Lapis Blau
1974 Mercedes 240D - 186,445 miles - Aqua Blau
1982 Volvo 244GL Diesel wagon - 168,956 miles - to be sold
1994 Chevy G30 6.5 Diesel "short bus" converted for camping, painted red white & blue & white stars 78,956 miles
JD F935 diesel front mower

Anytime.

Help is what we do here.

Sorry to revive an old post. But, I have a specific issue related to this. Specifically the 2nd to 3rd shift. I was going to post and ran across this thread in the search. I'm having a similar issue.

When you are referring to a "Flare"... What is this exactly? I'm assuming a slow shift and or a softer/slower shift?

Edit: Nevermind... I got the answer and help on a different forum.

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AJ

1985 300D (SOLD)

I need to revive this post a little.
On this SD that I have just about got on the road, I have shift flare in every gear. Really bad in some.
changed the fluid, and it was way bad. Do not know how long since it was last changed.
As part of this saga, I had to replace the vac. pump.
I now have 12 at the trans, So am I also down to adjusting the modulator by a turn or so at a time until I get the flare to go away?
Trans has good power if held in gear with the selector. But flares badly.
thanks

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83 300SD Dark Silver Dark brown inside

Adjust the VCV so that you've got 8" vacuum with the Mityvac and see how it performs. My SD is perfect at 8"

If that doesn't work, then it's time to increase the modulator pressure a bit.

Is the VCV on the side of the IP? or where? I bypassed the vac stuff on top of the valve cover.

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83 300SD Dark Silver Dark brown inside

Four years on the board, with four 617's, and you don't know where the VCV is yet?

Check that white object on the aft end of the IP..............I've only posted how to adjust it about 10 times or more.

ya, I was looking at adjusting.
Funny, how things slip by when you do not have an issue with it....
thanks for the help.

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83 300SD Dark Silver Dark brown inside

using the screw I could not adjust it below 12. I lengthened the rod, and got it down to 7-8. Shifts better, Now on to the modulator? 1 turn to start?

thanks

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83 300SD Dark Silver Dark brown inside

1 turn clockwise for a fine adjustment should be good.