1066 Hydraulic Issues

MN Scott · Jul 18, 2011

I was cutting hay today with my 1066. Turned at the headland and throttled up and it was slipping in direct drive. I also lost my hydraulic clutch assist, brakes and TA function. The steering works fine. I'm thinking its a MCV issue? This tractor has 3000 hours and has never had issues before.

Owen Aaland · Jul 19, 2011

You have the classic symptoms of a worn out MCV pump or a leak between the pump and steering. The TA lube light should have come on also. The steering gets 3 GPM priority flow from the MCV pump that is regulated to about 250 PSI for brakes and TA control. When the steering id being used the pressure in the steering circuit is limited to 1900 - 2100 PSI. If due to wear or leakage the pump cannot put out pressure in excess of the steering relief valve setting there will be no oil flow for the clutch assist, brakes, TA control, or hydraulic seat. Since the TA lube is oil that has passed the pressure regulator setting, if there is not oil for the controls there is no oil flow for the TA lube.

What doesn't show up but can be more critical is the excess flow from the MCV pump that exceeds the 3 GPM that goes to the steering, goes to the oil cooler and then to lubricate the range transmission and differential. When ever you notice problems with the controls or steering, the lube for the rear of the tractor has already been cut off. That is why it is important to keep the MCV circuit in good repair.

MN Scott · Jul 19, 2011

The TA light does not come on. It is [the light circuit] in working condition as it comes on when I depress the clutch. The tractor has not previously shown any signs of a weak or worn pump. So unless the pump had a sudden failure, it seems something like a valve stuck or an oring let go and the symptoms appeared. I'm going to borrow a friends gauges and check the pressures.

Owen Aaland · Jul 19, 2011

A sticking pressure regulator valve could be the problem but it should not be affected by RPM since it should have a constant 3 GPM flow. A sticking flow divider valve could cause the oil flow to drop with the lower engine RPMs but there again if you are getting less than adequate flow to the controls the pressure regulator valve, trying to maintain pressure, should close off all flow to the lube circuit causing the lube light to come on.

1066 Hydraulic Issues

MN Scott

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Owen Aaland

Well-known Member

MN Scott

Well-known Member

Owen Aaland

Well-known Member

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