Very odd need- want ads would be no help

I believe in cars for sale and major parts being in the classifieds where they belong and the WTB the same way, but since BMW does not even sell this part, I am asking for a little leeway here. I need a power steering pump DRAIN PLUG for a 540 Sport. Mine is a 2002, but a picture will tell me if it is the same. I was doing a three part oil change of power steering system and when I was re-installing the drain plug, it appears to be aluminum and has a lip around the top where the allen wrench goes in.

The lip on the threaded plug just "disintegrated"! That lip keeps the O-Ring for which a groove is cut out of the plug from being able to come out. I did not loose the drain plug, but it no longer has a "lip" on it to contain the O-ring. New pumps have the plugs in them, but you can't buy this plug by itself unless there is one on the tranny somewhere that is identical. If anyone is doing a P/S pump change out, can you not return the plug with the core and I will happily pay you for your time and shipping. I will get the metric size as soon as I can, but guess it is about 14 or 16 mm and a hex head or a regular head bolt of same size will not have a relief cut in it for a captive O-ring, Thx Bill

Feel free to PM me.

Will an old differential drain plug work.

it might..I have to wait for the crush washers I need for the banjo bolts on the P/S pump and I will drian one last time and measure threads. I would *guess* they are 14mm x 1.5.
Do you know size of diff. bolt? Thanks Bill