I think my modulator on my tranny is broken. It shifts hard into 2nd and 3rd, and smooth into 4th. My vacuum lines seem to be fine and the line to the modulator holds a vacuum. I have a modulator from an 83 380SE (red, trans number 722.310). My car has a black one and it's an 84 300SD and the trans number should be 722.416 I believe?
Can I swap them to try it out, or do I need that specific one?

send me your vin number in an email and i will check appilcation for you.
Ray
mercedessd@cox.net

where on the trans is the modulator located

I am in the process of fixing my vacuum system and next on the list is the modulator

Thanks

1984 300d

You've got mail

Ok I just came from "underneath the car" and I adjusted the modulator. When I shift at 1500 RPM it doesn't "clunk" anymore, and when I give it more throttle it doesn't do a burnout when it shifts into 2nd gear. Turns out the modulator is green instead of black, even though I thought the california ones are black.
When you have a modulator with the T handle on top and keep turning it left, is there a stop? Mine just becomes really loose after the adjustment stage. Is that supposed to happen? Or is there something inside it not "following" the adjustment?

hi, reviving this thread b/c i have a modulator from a donor transmission that got me out of first gear...

the car's a 1980 300d (non-turbo) and had the red vacuum modulator (trans # 722.118). i couldn't get out of first/second gear, but when i put in a white vacuum modulator from a 1979 300sd (trans # 722.120) i got all of my gears back, but am having trouble adjusting shift points.

my questions are:
1) will this white modulator work--does anyone have successful experience?
2) would my original red modulator be serviceable?

(oops, should i move this to diesel discussion??)
thanks a bunch!
-noah

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1980 300D (non-turbo, 421k miles)
1984 300TD (turbo, 305k miles)
1985 Vanagon (170k miles)