Don't cut it! I did and it was a mistake and a pain to find new parts. To get it apart you need to remove the two bolts that hold the top drain tube to the turbo. Then press the lower section down (it should move about 1/2 an inch before it bottoms out. Now twist and push up on the upper section until it is wedged up against the exhaust manifold. With the upper tube up as far as you can get it and the lower tube down as far as you can get it you should (barely) be able to remove the upper tube.

To get the bottom tube out you will probably have to destroy the old seal.

Remember you need an O ring for the top AND bottom of the lower tube. Use some grease to help you slide everything back together on reassembly.

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1979 240D- 316K miles - VGT Turbo, Intercooler, Stick Shift, Many Other Mods - Daily Driver

1982 300SD - 232K miles - Wife's Daily Driver

1986 560SL - Wife's red speed machine