Replacing the Turbocharger Oil Return Tube Seals
on Mercedes-Benz 617.952 Diesel Engines
Introduction
The technical material for this FAQ (Frequently Asked Question) was provided by the staff at Stu Ritter Mercedes-Benz Technician, Inc. of Denver, Colorado, was edited by Richard Easley of Baylor University.
Assumptions
Using the categories of mechanical ability from the Mercedes-Benz Discussion List, you need to be at the level of "Medium Do-It-Yourselfer" at minimum, to replace the turbocharger oil return tube seals. If you are below that level, you may want to provide these instructions for someone who is at the medium level or beyond.
Parts needed:
1. Spray brake cleaner
2. Silicone
3. Upper tube gasket
4. Lower tube O-rings
5. Lower tube (in case old one is/gets distorted)
6. Seal for lower oil pan hole (for lower tube)
7. Lower oil pan gasket
Picture of Turbo Oil Return Tube Seal Procedure
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Replacing the Turbocharger Oil Return Tube Seals
1. Pull the lower oil pan, yes, pull the pan (there are two). It only takes about 10 minutes.
2. Don't remove the turbo.
3. Do loosen the two bolts that mount the upper tube to the turbo.
4. Rotate that tube 180 degrees to facilitate removal of the lower tube.
5. Attach a heavy hose clamp to the lower tube that will enable you to tap on it from the bottom with a drift in order to remove the tube.
6. Remove lower tube.
7. Scrupulously clean O-ring grooves on lower tube.
8. Scrupulously clean hole in upper oil pan where lower tube slides through.
9. Install O-rings on lower tube.
10. Inspect seal and lower tube w/O-rings carefully. Do a "dry run" on inserting tube in seal on the workbench. Note how O-ring "seats" in groove on seal. Repeat until you are comfortable that you know when they are joined properly.
11. Lightly, lightly coat inside of lower pan seal with silicone (*very* thin, no excess).
12. Insert lower tube into seal and push through until lower O-ring is below seal.
13. Lightly, lightly coat outside of lower pan seal and lower O-ring on lower tube with silicone (*very* thin, no excess).
14. Install seal/tube assembly in oil pan until seal bottoms out along its flange.
15. Put upper oil return tube on top of lower oil return tube at 180 degrees offset from final fit.
15. Looking up at oil return tube from under car (through hole in pan), use a drift to tap lower oil return tube and lower O-ring in place. [For DIYers, read: a deep socket that is large enough to fill hole will work as a makeshift drift.]
16. After ensuring that lower oil return tube is seated, swivel upper oil return tube into place, slide new gasket in place, and bolt upper tube to turbo.
17. Clean lower oil pan and install new lower oil pan gasket.
18. Install lower oil pan and torque all bolts.
19. Refill engine with oil.
20. Check for leaks.
©1999
Richard Easley, Waco, Texas and Stu Ritter, Denver, Colorado.
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