sound pretty audibly on the 85 300 so is it perhaps a leak or is it urgent to swap it out? Its got about 230,000 on it

Uh---Hellooo?

is it a sucking sound... blowing sound what? your description leaves a lot to the imagination.

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hum.....
1987 300TD 311,000M Stolen. Presumed destroyed

Swish is kinda the noise a vacuum pump makes in normal operation.

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-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

Does that really mean anything? Is it producing vacuum? If so, how much?

It seems that a failure of the vacuum pump has some mechanical chatter or clicking before failure. I have been doing a lot of reading on this subject as I am about to rebuild mine.

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AJ

1985 300D (SOLD)