I recently acquired a 1968 1650 diesel that has been sitting a long time. After some fuel and clutch repairs I have it running. Then I found it had very low hydraulic pressure. Everything worked but poorly. Replaced the vane pump (had obvious wear inside the ring, like chatter marks) with a new gear pump. Now I have great hydraulic performance but also developed a rattle/hollow metallic ring in the pump area, that is LOUD. I have done the following:
- New pump from reputable dealer, new 3pt cylinder seals, new o-rings at all locations in hyd unit, new bearings on pump drive gear and idler gear, new pump gasket, 2 new gaskets for hyd unit to rear housing, steel elbow for 3pt cylinder relief
- The new pump without the gasket installed had 0.003-0.004" clearance between the mounting flange and hydraulic unit. So I wouldn't think the shaft is bottomed out in the gear.
- I lightly clearanced 2 ribs on the replacement pump with a file that appeared to touch the housing before installing. Definitely not touching now.
- No obvious wear on any of the pump drive gears
- Some wear on PTO drive shaft at flywheel but looks good at pump drive
- Removed hydraulic unit after new pump install to verify pump pickup is not touching reservoir pan (clearanced cup on pan slightly because test clay cut into 2 pieces)
- Replaced hyd filter 2x
- Remote spool valves were lightly stuck so I freed those and cleaned
- Checked flow divider, spool works freely. Small hole in spool land going to the dampening chamber is clear.
- Originally refilled with J20C hydraulic oil, drained and refilled with AW32
- Mowed about 1 hour and hyd filter housing just slightly warm to touch
- Relief pressure before the flow divider is 1900-2000 psi and steady
- Steering max pressure at flow divider 1500-1600 psi at steering lock
- Flow divider spool spring length is 4-11/16". Books says 4-25/32". So it is roughly 3/32" short.
The noise goes away at idle and slowly turning the steering. Like low hyd flow helps. Mowing with PTO loaded doesn't seem to change the rattle. Cranking the tractor without the PTO drive shaft eliminates the noise. Noise does not change with transmission clutch engaged or disengaged. Installing the PTO driveshaft halfway (front splines in hyd drive gear) and rocking shaft by hand seems to replicates the noise.
I shimmed the flow divider spool spring with 3 washers (about 0.120" total). The noise is noticeably better. Especially at 2000 rpm. Steering pressure measured before the flow divider, not turning the steering wheel, seems to have increased slightly. Went from about 200psi to maybe 300psi and gauge does not fluctuate as badly. I am guessing that this 200-300 psi pressure is a combination of the pressure required to open the flow divider and push oil through the rest of the system
Could the flow divider be my problem? Maybe a weak spring causing pressure fluctuations and the pump is loading and unloading causing the rattle? I thought about temporarily removing the flow divider spool spring to see if noise goes away and measure pressure without the divider doing its job.
Anyone have any thoughts or experience with such? I have read the 1650 pump makes noise but this seems a tad too much.
- New pump from reputable dealer, new 3pt cylinder seals, new o-rings at all locations in hyd unit, new bearings on pump drive gear and idler gear, new pump gasket, 2 new gaskets for hyd unit to rear housing, steel elbow for 3pt cylinder relief
- The new pump without the gasket installed had 0.003-0.004" clearance between the mounting flange and hydraulic unit. So I wouldn't think the shaft is bottomed out in the gear.
- I lightly clearanced 2 ribs on the replacement pump with a file that appeared to touch the housing before installing. Definitely not touching now.
- No obvious wear on any of the pump drive gears
- Some wear on PTO drive shaft at flywheel but looks good at pump drive
- Removed hydraulic unit after new pump install to verify pump pickup is not touching reservoir pan (clearanced cup on pan slightly because test clay cut into 2 pieces)
- Replaced hyd filter 2x
- Remote spool valves were lightly stuck so I freed those and cleaned
- Checked flow divider, spool works freely. Small hole in spool land going to the dampening chamber is clear.
- Originally refilled with J20C hydraulic oil, drained and refilled with AW32
- Mowed about 1 hour and hyd filter housing just slightly warm to touch
- Relief pressure before the flow divider is 1900-2000 psi and steady
- Steering max pressure at flow divider 1500-1600 psi at steering lock
- Flow divider spool spring length is 4-11/16". Books says 4-25/32". So it is roughly 3/32" short.
The noise goes away at idle and slowly turning the steering. Like low hyd flow helps. Mowing with PTO loaded doesn't seem to change the rattle. Cranking the tractor without the PTO drive shaft eliminates the noise. Noise does not change with transmission clutch engaged or disengaged. Installing the PTO driveshaft halfway (front splines in hyd drive gear) and rocking shaft by hand seems to replicates the noise.
I shimmed the flow divider spool spring with 3 washers (about 0.120" total). The noise is noticeably better. Especially at 2000 rpm. Steering pressure measured before the flow divider, not turning the steering wheel, seems to have increased slightly. Went from about 200psi to maybe 300psi and gauge does not fluctuate as badly. I am guessing that this 200-300 psi pressure is a combination of the pressure required to open the flow divider and push oil through the rest of the system
Could the flow divider be my problem? Maybe a weak spring causing pressure fluctuations and the pump is loading and unloading causing the rattle? I thought about temporarily removing the flow divider spool spring to see if noise goes away and measure pressure without the divider doing its job.
Anyone have any thoughts or experience with such? I have read the 1650 pump makes noise but this seems a tad too much.