For years Iv pulled my 6 row 7200 planter with my 4440. This year I want to put my 6603 on it. The 4440 has closed center hydraulics and the 6603 has open center hydraulics. What do I have to install on the open center tractor to run the vacume motor so the hydraulics wont heat up? Is it as simple as just dumping the return oil to sump? or is another valve required?......