Did this on my daughters 240D. A very easy job exept for one thing. Be very carefull when disassembling the pump. Make sure you know exactly how everything came apart. If you assemble it wrong it will not work. Take pictures of every step. When you pull the shaft, do it very slowly so you can see how all the parts are assembled.
I pulled the shaft and everything dropped out. If this happens to you the stains in the metal parts will help you reassemble it. This is what I did.the impellers should go in on one direction. YOu can look at the wear on them and determine this.

Otherwise it is an easy job. Just the one gotcha.

Dave

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1970 220D, owned 1980-1990
1980 240D, owned 1990-1992
1982 300TD, owned 1992-1993
1986 300SDL, owned 1993-2004
1999 E300, owned 1999-2003
1982 300TD, 213,880mi, owned since Nov 18, 1991- Aug 4, 2010 SOLD
1988 560SL, 100,000mi, owned since 1995
1965 Mustang Fastback Mileage Unknown(My sons)
1983 240D, 176,000mi (My daughers) owned since 2004
2007 Honda Accord EX-L I4 auto, the new daily driver
1985 300D 264,000mi Son's new daily driver.(sold)
2008 Hyundai Tiberon. Daughters new car