lantraxco, you are absolutely correct. I looked inside the coupler with a bore scope and splines were stripped. It was my first thought when I realized neither pump was putting out pressure.
(So, are these things usually designed so that one pump provides power to the front and the other pump to the rear?)
The coupler was rusted solid to the plate that attaches to the crankshaft pulley. So, I couldn't remove it to look inside and it's mounted in such a way I couldn't even stick a mirror in a position to see. Then, my mind started playing tricks on me. My bias against how Europeans set things up in unconventional ways convinced me there was some other point where these two systems converge.
After I confirmed with the bore scope, since I couldn't unscrew the coupler even with heat and oil I spent a good 10 hours dropping the front cradle so I could slide it out.
Now the problem is finding that coupler. It's a Parker pump. I went to the Parker hydraulics dealer, they said they have no information on that pump, despite the Parker tag with the model number. They offered to have a machine shop fabricate a coupler for $700. I also have Motion Industries looking to see if someone sells a ready-made coupler. The pump is a Parker model 76383 if anyone happens to know the spline size. Hub City makes couplers. I downloaded a copy of the catalog, but I don't understand how to read spline sizes. For instance, it has 15 splines. Under their "involute splined couplings" chart, the description for their 15 spline coupler is 16/32" DP 30 deg PA. No idea what that means. PA = pitch angle maybe? Don't know what 16/32" measures.
