I'm reviving this old thread because on my '84 300SD the oil separator drain is still secured rather well with the bracket, and I need to remove this drain tube in order to replace the o-rings on both its ends (thought I'd take care of this while I am removing the oil catch pan to replace the gasket down there, and take care of this and the lower part of the turbo drain pipe too).

Sooo... What size wrench do I need to free the separator drain tube? 10mm?

There seems to be a larger bolt and a smaller bolt, from what I could conclude in looking up from under the car -- the large bolt securing the bracket to the exhaust manifold and the smaller bolt securing the drain tube to the bracket?? Do I have this right?

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84 300SD - bought in April '06 with 237,000 mi