You go to your local hydraulic pipe shop fitter. Bring the in and out pipe from the oil cooler/pump. Have them take the two in and out fittings for the pump off the existing pipes (or find new matching fittings). Fit the fittings on a approx 200mm long HP pipe, (re-inforced so you can bend it back 180 degrees, without it collapsing in the bend).
Fit the fitting fittingly to the oil pump, and the oil side is taken out.
If you have already disconnected the water side, you can remove the oil cooler.
(It is possible that it is no necessary to fit the pipe, and in stead just blank the holes, but if this is a full flow cooler, then it is necessary. I just fitted one to make sure I did not take a chance and it has worked fine for a couple of years.)
