I have replaced all hoses and cylinder rods where they were worn. Very slow hydraulic actions for blade side shift, tilt, rotate etc and tilt front wheels etc ie. all hydraulic functions. Hydraulics tested: 1000PSI at idle and drops to 300 at full revs. Oil tank full, filters OK. Full oil flow out of pump feed hose when changed pump. Put a new pump on and get no pressure at all. The pump is run from a shaft at the bottom of the Alison transfer box in front of the motor. Steering is separate and via a small pump in front of the radiator and driven by a belt from the fan pulley. There is a slave cylinder then a larger cylinder to steer. It takes about 100 yds or meters to turn about 45 degrees even using the wheel sloping. 1.My thinking is that the stub shaft in the Alison transfer box is broken? The loss of pressure in the old pump may be due to passive thrust on the shaft and oil going to the side of the gears. I think it is the right hand thumb rule re thrust . Maybe Left hand rule for thrust. The new pump has put more resistance on the potentially broken stub shaft hence no pressure. 2.Re Steering turning circle: Maybe due to stuck differential or brakes stuck on hence they are tending to push the grader straight forward. Any ideas please as I cannot find any mechanic who has any knowledge of the Malcolm Moore Grader in Melbourne. I found this site via Farmcraft 101 who mentioned he has had a lot of help re his oldish machinery.
Welcome to HEF. If all of your readings are correct I would suspect a collapsed suction line from the pump to the reservoir. When I say collapsed I mean internally, not necessarily visible on the outside. At idle the restriction is open enough to allow some flow but at high idle it pulls in the restriction. I don't know if you have a filter in line or in the tank, possibly just a screen, but it is worth checking also. I have seen many hoses through the years that look ok on the outside but not inside.
Thank you so much for your advice. I'll have a look on the weekend.
Can you post some pics. of the machine. Always nice to see different machines.
by all means post some pictures i`ve never heard of one of these