My son's 87 wagon has literally stopped shifting except between first and reverse. Traced it back to the vacuum modulator on the transmission. Vacuum is exactly correct with that vacuum line plugged. And the Mighty vac pulls zippo vacuum on the modulator valve...more correctly, a small amount which zeros out very rapidly...read that instantaneously.

I know the modulator can be "tuned" but I seriously doubt that would erase the vacuum loss. If anyone has any ideas, please send them my way.

In the meantime, not one of my manuals or guides has information about replacing that modulator. I have searched on line and so far found nothing useful. Can someone provide some information or a source for the removal and installation of the unit?? I am not very good at flying blind with such a repair.

Thanks, Frank

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old goat

86 300SDL - 207K
84 300DT - 298K - sold
78 450SL - 97K
61 Porsche - rare T-5 Karmann Hardtop - NO, NOT a Karmann Ghia
99 Suburban 4x4 - 247K all original, the family donkey

To replace the modulator on a 722.xxx transmission, it's simple, it is held by two 5 mm allen bolts and a metal retainer.
First clean and degrease the modulator area very well.
undo the two 5 mm bolts, pull the metal retainer up. and pull the modulator straight out, you may have to rock it as you pull.
there is a modulator valve pin,and a pressure pin inside the bore,use a new o-ring/seal when reinstalling.

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1986 190D 5 cyl. 5 speed manual White (215K),
1983 300SD Silver blue (103K)

Thanks for the information....and the easy comment as well! I have to look at it closer than I did as I do not remember a retainer but must have missed it. Based on looking at the new part, the retainer must go over it. Perhaps more dirt and oil on it than I thought.

Frank

__________________
old goat

86 300SDL - 207K
84 300DT - 298K - sold
78 450SL - 97K
61 Porsche - rare T-5 Karmann Hardtop - NO, NOT a Karmann Ghia
99 Suburban 4x4 - 247K all original, the family donkey