1994 E320 Wagon 250,000 miles original transmission (B3 friction discs replaced about 10K miles ago) regular ATF fluid/filter changes since new Over the last 6 months, car has developed slightly harsh upshifts, 3 to 4 shift seeems to be the worst. I suspect vac mod or vac leak problem. Checked vac system for leaks by visual inspection and with Mighty Vac tool--none found, vac mod circuit will hold 15 inches of vac with no leakdown. So my question: is it possible/likely that the vac mod is defective even if it holds vacuum? I did try to reduce pressure slightly be adjusting the vac mod pin--harsh shifts still present. If anything, the adjustment resulted in a very slight flair in the 2-3 shift. Thanks for reading. J. M. van Swaay

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1994 E320 Wagon, 230,000 miles
1995 E320 Sedan, 106,000 miles
1994 E500 Sedan, 79,000 miles

Yes, the modulator could be defective & still hold vacuum.

Could also be that the engine is making less vacuum. (valve job?)
Is the compression still good?

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Thanks for the response. I haven't done a compression check--engine runs strong and produces very adequate power. Valves were done about 70K miles ago when I did the head gasket. I do have a compression tester set up--I'll do a check next time I'm under the hood.

A new vac mod was about $40 last time I checked--maybe (against my better judgement) I'll try the throw parts at it and see if it fixes it approach......

J. M. van Swaay

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1994 E320 Wagon, 230,000 miles
1995 E320 Sedan, 106,000 miles
1994 E500 Sedan, 79,000 miles