Torque converter should always be drained, else you are only changing about a third of the fluid. Why leave old nasy dirty fluid in there?

In the case of most automatics, it isn't possible to drain the torque converter, there isn't a plug. To drain a US one, you usually have to drill a hole (two, actually, 180 degrees apart) and insert a plug when you are done. MB nicely provides a drain plug.

If, however, you don't drain the convertor, but look in the book for replacement volume, you will put in several more quarts of fluid than you should. May or may not register as seriously overfull on the stick, but it will blow out the vent when the tranny gets hot.

It wasn't leaking, it was dumping fluid out the top vent.

I've ALWAYS added a couple quarts, then checked frequently while adding the rest of the fluid, it's too hard to get the excess out if you overfill.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!