So a while back I replaced the vacuum modulator on my tranny because I discovered ATF in the vac line. Now I'm experiencing the same problem. With the engine running it sucks a steady line of ATF through that line.

Why would this happen on a new part? Also, does the color of the modulator have anything to do with functionality? I think my old one was green, this one is black or something like that.

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1992 300D OM602

Ben

Because the problem is a leaky modulator.

Ah yes, I made a mistake. It is the modulator that I replaced earlier.

What would cause a new modulator to leak? If you unscrew the adjustment on it too much would that cause leakage?

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1992 300D OM602

Ben

Isn't there an o-ring inside it you can replace? Maybe it came with a bad oring.

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What Would Rudolph Do?
1975 300D, 1975 240D, 1985 300SD, 1997 300D, 2005 E320 , 2006 Toyota Prius

I have encountered NEW defective vacuum modulators.
It is not common, but it does happen.

.

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ASE Master Mechanic
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Thermal & Aerodynamic System Engineering (TASE) Senior vehicle instrumentation technician.
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1985 300SD
1983 300D
2003 Volvo V70

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