3-Point Hitch help please i have lost all hydraulic pressure on my MT1601D

[lens12]

The transmission is also the hydraulic supply. The pump is engine mounted . Single clutch.

 

[Industrial Toys]

Yeah. A friend was having problems with the hydraulics on a Bolens. He dead headed the pump and it virtually blew right off the block breaking the casting.

 

[ch85st]

If it is plumbed correctly, which I assume it is, (unless something was changed when doing the clutch) the 3 point & loader are separate systems. The 3 point control valves have a tendency to get dirt in the relief valve & stick, but the loader should still work. The black oil is a puzzle. A common error is not hooking the hydraulics back up after working on the tractor & dead heading the pump. This blows the internal & external pump seals. Usually the hydraulic oil dumps into the motor, not vice versa. What oil are you using?

Thank you
As i didnt do the clutch job myself i cant be sure but i think all hoses are correctly attached.
yes reg the 3 point i did clean the control valve and all moving things is back to moving
Regarding the Black oil, when i had the Hydraulic Block off i noticed there was at least 1 cm of Gunk in the bottom of the case
So cleaned all that out with diesel. also managed to get hold of a Metal screen for the Filter (found a larger filter for an old Russian Tractor ) and managed to attach and seal the metal screen on to my filter.
As i had enough of buying new expensive SAE 80 (transmission/hydraulic Oil) i filtered the oil from last change (only used for 1 hour and Grey not totally black) and put it back for testing if anything worked
the oil havent been getting any darker So might have been all the Gunk that made the oil black when the filter screen broke.
MY Last hope before sending the whole tractor in to someone that knows how to check and repair a hydraulic system.
I have been thinking that IF there is a relief valve on the control valve for the FEL stuck open, it might be that keeping the whole system from getting pressurized ?

 

[ch85st]

Do NOT take the FEL valve apart. You will only make things worse.

The valve has no internal seals between the spools and the valve body. The manufacturing tolerances are so fine that without a seal oil cannot escape.

The black hydraulic oil is a clue not to be overlooked.

Is the hydraulic oil the transmission oil? If it is then there is a leaking crankcase seal from your clutch job. Perhaps the seal was put in backwards.

How many hoses on the FEL valve?

Where is the hydraulic pump mounted? When I think about you doing a clutch job, I need to know if your tractor has live pto. If the pump is not mounted on the engine, could you have not assembled the double clutch properly and now there is no power going to the hydraulic pump?

Dave M7040

Thanks again for taking time to read and answer
pump is engine mounted, and from what i can tell its pumping oil as its moving thru the system.
As i didnt do the clutch job myself it could be something like you suggests. but as i replied to another answer i found at least 1 cm of Gunk in the hydraulic case and have cleaned that out now + mounted a new screen to the broken filter, so could be that that made the oil black.

 

[ch85st]

The transmission is also the hydraulic supply. The pump is engine mounted . Single clutch.

yes totally correct

 

[ch85st]

Yeah. A friend was having problems with the hydraulics on a Bolens. He dead headed the pump and it virtually blew right off the block breaking the casting.

Not on this one all seems fine and oil is flowing thru the system.
Im thinking a relief valve on the Control valve for the FEL

 

[ch85st]

Well im Away for a few days so will need to let it sit for a while
But im thinking it MIGHT, just Might be a stuck open relief valve on the control valves for the FEL.
Im not sure but when i think about it i dont remember the return from the FEL was having oil going back in to the transmission case all the time before ? might have been just when moving the FEL that the oil was returned to the reservoir ?
Could it be that thats the reason to no hydraulics having pressure?
IF thats not a possible reason to why i have no hydraulics working, i will have to find a specialist on these types of small Jap tractors and have it repaired by them, i have 25 tons of gravel in the yard that needs leveling so must get it working in a near Future .

 

[Dave M7040]

The transmission is also the hydraulic supply. The pump is engine mounted . Single clutch.

Be careful using a pressure gauge. You do NOT want to hook it at the end of a line that might not have the relief valve between the pump and the gauge.

I suggest you first see if your pump can deliver a reasonable volume of oil without worrying about the pressure. Come up with a temporary line connected to the pump output with an open hose which you can direct into a clean bucket so you can reuse the oil. This would be a connection at the put outlet and certainly before the hydraulic block.

The pump should be able to deliver at least 6 US gallons per minute or 22 liters per minutes with the engine at full speed.

If it does not deliver close to that volume you either have a restriction in the suction line, screen or filter. Or a serious air leak into the pump suction.

A pump which will deliver the proper volume will usually deliver the oil at pressure as well so this is a test you can do without a pressure gauge.

There should be oil constantly returning to the reservoir from the FEL valve. A hose in the wrong place does weird things if you removed any or all hoses.

Dave M7040

 

[Industrial Toys]

Wouldn't the relief valves for the loader be downstream of the loader valve, like on the other side of the valve? But maybe your open center valve is hooked up wrong so the oil never stops flowing at low pressure. Not interrupting flow to provide pressure to a given circuit.

 

[Dave M7040]

Wouldn't the relief valves for the loader be downstream of the loader valve, like on the other side of the valve? But maybe your open center valve is hooked up wrong so the oil never stops flowing at low pressure. Not interrupting flow to provide pressure to a given circuit.

I am not trying to argue with you so please keep that in mind.

The typical hydraulic circuit is from the main pump to the power steering which has its own relief valve and is fed by a priority flow control so it always has first opportunity for pressure.

Next is the FEL valve which has its relief on the inlet to the valve block.

Often the FEL will feed the rear of the tractor from a power beyond port on the FEL valve block. If this is what is happening, there will be 7 hoses on the FEL valve not 6. .

The PB circuit will have its own relief valve even though it is limited by the FEL relief valve setting. It can be set lower but will not set higher than the FEL relief.

In addition to the relief valve for the 3 pt and any rear remotes, there is an additional safety valve in the 3 pt circuit to deal with a heavy implement bouncing on the 3 pt arms.
The safety valve is set much higher than any relief valves on the tractor and has to be removed and set up with a special tester also used to calibrate fuel injectors.

With any open center hydraulic circuit, oil is constantly flowing through the individual valves and back to the reservoir all at low pressure. Oil should always be flowing in the open center system.

That is why the output of the pump can never be cut off or dead headed as the pump is a constant displacement type and for each revolution of the pump MUST deliver a specified amount of oil measured in c.c.'s.

Dave M7040