# Ford 4600 Hydraulic Issues



## roncumlander (Dec 30, 2016)

I have a Ford 4600 that I purchased with hydraulic system issues. I have replaced all o-ring seals in the lift top cover, lift cylinder, ball check valve, broken feeder tube to the lift top, cracked aluminum elbow between the oil filter assembly and the hydraulic pump, and installed a new hydraulic pump. Front end loader works fine so long as their is no load on the lift arms. Lift arms go up and down fine with no load.
Hook my bush hog to the lift arms and the lift picks up initially, then after 10 minutes or so gradually loses lift ability. With the bush hog load on the lift arms (trying to pick up), you can here a noise coming from the spool valve assembly that operates my front end loader. When the lift arms are let all the way down, the noise goes away.
There is no selector valve under the seat mounted on the lift top cover. Whoever installed this front end loader simply raised the cap on the lift top cover and installed an aluminum block with the same porting pattern under the cap with longer bolts in order to hook the front end loader supply and return lines to the system.
I am under the assumption this tractor requires a selector valve to choose between the lift and the front end loader. I don't think the pump is capable of delivering the amount of required pressure to both at the same time OR the relief valve on the lift cylinder needs to be adjusted because it may be releasing too soon. Help.


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## RC Wells (Dec 26, 2008)

I suspect this was answered along the line, but if not pull the three point cylinder assembly from under the seat and rebuild the piston.

Your pressure is going south through a leaky three point piston.


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## roncumlander (Dec 30, 2016)

RC Wells said:


> I suspect this was answered along the line, but if not pull the three point cylinder assembly from under the seat and rebuild the piston.
> 
> Your pressure is going south through a leaky three point piston.



I did not replace the piston but I did replace the piston o-ring and PTFE gasket on the piston.


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## dozer966 (Dec 30, 2014)

I'm trying to visualize your HYD system and what I can think of is that pressure gose from pump to loader control valve which has power beyond then goes to 3 point hitch. If this is correct I would suspect the loader control valve to be the culprit. Do you know if this is your setup. How many hoses are on the loader control valve


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## Fedup (Feb 25, 2014)

Good question on the total number of hoses. It should be seven and not six. The aluminum block should have three ports connected to the valve, not two. I too believe the loader valve is at least part of the problem. I suspect the noise you hear there is it's relief valve. Hopefully it's adjustable and can be turned up above 2500 psi which is the system's designed pressure setting. This is (or should be) controlled by the internal relief valve built into the hydraulic pump. If you have another valve in the circuit as described and it relieves at anything lower it will reduce the lift capacity of the three point. If the loader valve has an adjustment, try turning it in a couple turns and see what happens. 
On the other hand, if the loader valve has only six hoses, that raises other concerns.


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## RC Wells (Dec 26, 2008)

Does your aluminum block look like this? If so you have two ports, one is pressure out and the other is the return.









If this is the case, remove the two hoses from the block and plug the holes. Standard 3/8 NPT fittings so the plugs are easy to obtain. If the three point works great with the block plugged, then focus on the loader valve. If not, pull the block and verify the O-rings are in place and in good shape. Also check to be sure the block was not installed with some goofy RTV gasket maker that is allowing air intrusion or oil passage between the internal ports.


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## BigT (Sep 15, 2014)

I don't think that we can plug these ports, I think we have to use a jumper hose between them. The 'power beyond' plate puts the loader control valve in series with the lift. If we plug these ports, I think we will deadhead the pump.


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## dozer966 (Dec 30, 2014)

I think BigT is correct. The plate is designed for power beyond but we will not know till roncumlander answers us. Pictures of the setup would help.


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## roncumlander (Dec 30, 2016)

dozer966 said:


> I'm trying to visualize your HYD system and what I can think of is that pressure gose from pump to loader control valve which has power beyond then goes to 3 point hitch. If this is correct I would suspect the loader control valve to be the culprit. Do you know if this is your setup. How many hoses are on the loader control valve


I have replaced the loader control spool valve with a new one. I have even isolated the FEL from the hydraulics as though there is no FEL on the tractor with the same results with the lift. I am trying to find a used lift cylinder in a salvaged 4600 to totally replace mine if replacing and properly setting the lift cylinder relief valve does not resolve the issue.


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## RC Wells (Dec 26, 2008)

That plate just free flows. Without the diverter valve installed on top of the cover itself the only shutoff controls are the three point valve and the loader valve. Plug the pressure port on that plate and all the oil is diverted to the three point. Will not blow anything, all the passages in the top cover remain open.


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## roncumlander (Dec 30, 2016)

RC Wells said:


> That plate just free flows. Without the diverter valve installed on top of the cover itself the only shutoff controls are the three point valve and the loader valve. Plug the pressure port on that plate and all the oil is diverted to the three point. Will not blow anything, all the passages in the top cover remain open.


My spool valve has 6 hoses. The aluminum block looks like the one posted by RC. I have removed this block and reinstalled the cap on the lift top cover with shorter bolts totally isolating the FEL from the hydraulic system. The lift still behaves the same way. I totally suspect it is either the relief valve in the lift cylinder or the lift chlinder itself is blowing by the piston although I have replaced ALL seals. It may simply be worn out.


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## roncumlander (Dec 30, 2016)

roncumlander said:


> My spool valve has 6 hoses. The aluminum block looks like the one posted by RC. I have removed this block and reinstalled the cap on the lift top cover with shorter bolts totally isolating the FEL from the hydraulic system. The lift still behaves the same way. I totally suspect it is either the relief valve in the lift cylinder or the lift chlinder itself is blowing by the piston although I have replaced ALL seals. It may simply be worn out.


UPDATE: I found one of the four bolts that pull the lift cylinder up tight to the bottom of the lift cover was stripped. I replaced it and made sure the female thread was OK. Pulled it up good and tight. also, took the relief valve out of the lift cylinder while I had the lift cover off and plugged the port. 
Reassembled. hooked the bush hog up and the lift raised like it was supposed to all the way to the top with the draft and position levers all the way up. Bush hog would also stay in position with the Draft lever all the way down and using the position lever. I have taken the relief valve and tested it to insure it is set to 2,850 - 2,950 per the manual; it is.
After tractor and oil warmed up good, lift began to "bob" down and back up about 6" consistently. Manual states this could be 1 of 8 different things. Decided to take it to the New Holland dealer this Saturday. Tired of the challenge at this point. Need my tractor working. will update with the dealer's findings.


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