Dan,

I generalized my remark of the leak, so do not get confused. It is from"that rear area" too...Yes, the seal retainer plate. Where is the leak? who knows...The mating surface area to the engine, or the bottom, orrrr the round seal it self?

Now I have done a handful of rear main seals on different engines, but not the M112 and M113. Possibly this is my speculation for the moment is I have not look at Mercedes EPC here in the USA against my VIN to see if a revised seal plate exist. Consequently, the revision will mean the rear engine seal has grown in girth to acomodate more wobble in the engine shaft so it seals better, but biggest issue is how do you seal the bottom of the seal plate to the oil-soaked oil plan gasket. In both cases, I have wicked-up the oil with denatured alcohol. wipe everything denatured alcohol, so the high performance silicon sticks. The reality is to obtain a perfect seal one has to replace that whole oil soaked oil pan seal to do a perfect job-not just remove the transmission, or lift the engine out to replace the oil pan seal(s).

I'm rebuilding 722.5 right now, and the same issue will be encountered the engine seal. Now this 722.5 mates up to M104, and Mercedes revised the girth the rear engine seal by double, but the old seal plate had a valley milled out where Mercedes added molded rubber seal plate(that was nice, and some engineering!). Today's seal plates are just plain aluminum, so how does one do a perfect job? I think one of the pan gaskets has to be replaced and the rear seal plate.

That tool, I just hammered my in with a piece of 2x4 over it,so it covers the entire seal.

I have not inspected my rear seal with a inspection camera from harbor freight, but I have feeling you are right that is not the seal, but the plate.

Martin