I have a small orbital valve off of a toro tractor i want use on another tractor it has 5 ports P.T.L.R. and E . The E. Stands for excess how would you run this line would it simply return to tank does it have to be alone or can it tee in with tank return ... tractor has a 2 port block pressure and return always circulation that also powers the hitch on the rear Does the E .port have to go to tractor valve block return or just dump to tank???? Thanks

Did you run a check valve on the pressure line leaving the pump?