Hi All,

I am having issues with how hard the transmission shifts.
The transmission modulator cap was broken and when tested it did not hold vacuum.
The cap has been replaced and the tranny modulator DOES hold vacuum now.
The door locks work, slight delay now in shutting off engine.
Tranny fluid and filter are new, and at the correct levels
What would you guys suggest for the next things to test?
The shut off valve DOES work.
The transmission is not responding to any adjustments with the "T" adjuster...does this mean the modulator is bad?

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Did you confirm you have full vacuum when the engine is running to the modulator?

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Best Regards,
Jeff L

1984 300SD 247K+ miles - single tank w/ heat exchanger to run WVO - sold
1997 Ford F350 7.3L International turbo diesel crew cab with 100 gal transfer tank to hold B100
1995 E300D 245K+ miles running BioDiesel - my daily driver

Live Long and Prosper

Yes it has vacuum. 13 inches. My understanding is, if the vacuum is reduced it will soften the shifts. Where would that adjustment be made?

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Are the hard shifts when accelerating or decelerating?

Adjustment info.
http://www.continentalimports.com/ser_ic20242.html

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84 300D, 82 Volvo 244Gl Diesel

shifts are good if you stomp it
shifts are hard going slow and decelerating

EDIT:

tech says ALL the time

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I had the hard downshift about 2 weeks ago. It was due the Vacuum Tubing not connected down next to the Modulator.

After I put it back on hard downshift was gone.

I checked to see if the Modulator Held Vacuum from the line going to it under the Hood and it gradually lost Vacuum. When I checked direcely at the Modulator it held Vacuum.
What I found is my Vacuum leak was from the short lengths of Hose that go on the end of the plastic Vacuum Tubing.

A source of a Vacuum leak that might not show up at idle are the little Valves up on the Valve Cover that control the EGR.

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84 300D, 82 Volvo 244Gl Diesel

That would be a misunderstanding.

The modulator should never get "full" vacuum. If it does, the vacuum control valve is not doing its job.

newtodiesel: I'm not sure if your 300D is the same as my former 300SD, but check out this page and see if your control levers are OK. http://dieselgiant.com/trannyleverreplace.htm

Thanks tangofox. I think I'm getting my transmission controls confused between my former 300SD and my current E300D

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Best Regards,
Jeff L

1984 300SD 247K+ miles - single tank w/ heat exchanger to run WVO - sold
1997 Ford F350 7.3L International turbo diesel crew cab with 100 gal transfer tank to hold B100
1995 E300D 245K+ miles running BioDiesel - my daily driver

Live Long and Prosper

EGR has been disconnected.
Door locks trunk and fuel flapper had also been disconnected, still same symptoms.

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Maybe that VCV valve that I pulled a while back WILL come in handy. Will try that.


Modulator gets 13 inches of vacuum at idle

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Thank you kickit, My set up is different. I dont have those little fingers.
My set up has the blue flying saucer and the vcv it is an 85 federal

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I figure i should chime in since im the one doing the work for newtodiesel.

The transmission seems to be getting proper vacuum. The tranny modulator IS HOLDING vacuum. I have turned the modulators adjustment 1 full turn in both directions but the tranny is NOT responding to any adjustment i make, i returned the adjustment to its original position since nothing changed.

Even though the modulator holds vacuum, could it still be faulty?

Could it be something in the valve body that has gone bad?

This has me stumped and i dont want to throw parts at the problem....

Thanks guys and gals.

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1985 300TD Turbo Euro-wagon
1979 280CE 225,200 miles
1985 300D Turbo 264,000 miles
1976 240D 190,000 miles
1979 300TD 220,000

GONE but not forgotten
1976 300D 195,300 miles
1983 300D Turbo 175,000 miles

http://i42.photobucket.com/albums/e3...e485-1-2-1.jpg

Sure. If it's original, you can't go wrong if you replace it.

Kerry helped me a lot with my 81 300SD which I have just about got right. I would suggest you do what Kerry suggested for me. Unhook the vac line to the tranny and hook it up to the mity vac. Drive around with the mityvac inside the cabin. The car should upshift OK since it does not need vacuum for upshift. After you reach fourth gear, pump up the vac in the mityvac and come to a full stop. If it downshifts OK, things are working right. So if it upshifts fine without vac and downshifts fine when you pump up the mityvac, you must have a vac leak in the system.

Not sure the 300D is exactly the same as the 300SD - and I know for sure the vac system is different because the vac for door locks is via a separate pump in the trunk - but I would guess the general premise is the same.

If you turn the vac modulator CCW you will get softer shifts going finally to a flare. CW of course gives sharper shifts.

I know a good deal now about the SD but not about the D - hope this helps. There are a lot of guys on the forum who can help. What I found out working on mine is that the transmission may act really bad but the tranny may be good and the problem in only in the vac system - that was the problem with my new (used) tranny.

Can anyone else confirm the idea that "vacuum isnt needed for soft UP shifts, only needed for soft DOWN shifts"? I dont know about that, however i could be wrong.

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1985 300TD Turbo Euro-wagon
1979 280CE 225,200 miles
1985 300D Turbo 264,000 miles
1976 240D 190,000 miles
1979 300TD 220,000

GONE but not forgotten
1976 300D 195,300 miles
1983 300D Turbo 175,000 miles

http://i42.photobucket.com/albums/e3...e485-1-2-1.jpg