# Ford 4600 Hydraulic problem



## Zoin (Jun 2, 2021)

Hello
Just joined the Tractor Forum to get some advice so this is my very first post.
I have a Ford 4600 that I was using today with a box blade. I also have a loader on the tractor as well. I was switching back and forth between the loader and the box blade using the isolator valve under the seat. I was having no issues until I decided to switch from the hydraulics from the rear lift arms to the loader but this time I was holding the lever open for the loader to lift at the exact same time I pulled the knob on the isolator valve. It made a slight different noise while pulling the isolator valve knob out than normal and after that the hydraulics worked snail pace slow. Not sure how to explain the sound but the hydraulics don't sound the same anymore either. I pulled the isolator valve off and looked at the O rings under the plate and all look fine. I pulled the actuator shaft out of the valve and looked at it and I see one single O ring on there that looks fine too. Any Ideas what is going on? As slow as it moves I lifted the loader arms all the way to the top and down again. I had the thought that there might be an air lock in the system. I did a full fluid and filter change two weeks ago and it was working just fine since then till now. The tractor only has 700 hrs on it. Oh by the time I got the tractor to my garage and was parking it the hydraulics would not lift the rear arms or the loader at all. It seems like what ever caused it was caused by me doing both controls at the same time but it might be only a coincidence, I don't know. I think the tractor is a 1978 but not exactly sure.
Your trouble shooting questions and suggestions are appreciated, thanks


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## Zoin (Jun 2, 2021)

Ok some new information
I just went back and assembled it. The rear arms are working at normal speed (they were probably working at normal speed before, I was just mainly looking at the loader arms not moving properly) but the loader arms and bucket is slow. Here is an odd issue. Prior to all of this when I used to move the isolator valve from rear arms to loader the rear arms would drop. They now stay up but work normally as they should with quick response and fast motion. Still shows full on the stick for fluid.


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## BigT (Sep 15, 2014)

Zoin said:


> Ok some new information
> I just went back and assembled it. The rear arms are working at normal speed (they were probably working at normal speed before, I was just mainly looking at the loader arms not moving properly) but the loader arms and bucket is slow. Here is an odd issue. Prior to all of this when I used to move the isolator valve from rear arms to loader the rear arms would drop. They now stay up but work normally as they should with quick response and fast motion. Still shows full on the stick for fluid.


Before this problem, when you moved the isolator valve from rear arms to loader, the rear arms would drop? With a box blade on them or empty? Did the lift arms drop all the way down? You say now they stay up and work normally with the isolator valve in the loader position? That tells me that your isolator valve is not switching all the fluid to the loader.


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## Zoin (Jun 2, 2021)

BigT said:


> Before this problem, when you moved the isolator valve from rear arms to loader, the rear arms would drop? With a box blade on them or empty? Did the lift arms drop all the way down? You say now they stay up and work normally with the isolator valve in the loader position? That tells me that your isolator valve is not switching all the fluid to the loader.


The rear arms would drop when empty or loaded when you moved it to loader. They would drop all the way down. The rear arms do not work in the loader position they only do not drop like they used to in the loader position. The valve was cleaned of the very little dirt and seems to be moving back and forth normally.


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## BigT (Sep 15, 2014)

It appears to me that the lift arms are not dropping now because they are being supplied with fluid to maintain position.


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## Zoin (Jun 2, 2021)

BigT said:


> It appears to me that the lift arms are not dropping now because they are being supplied with fluid to maintain position.


Ya was thinking the same but from where?


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## BigT (Sep 15, 2014)

Zoin said:


> Ya was thinking the same but from where?


Could be from the isolator valve, it's not providing much to the loader valve?


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## Zoin (Jun 2, 2021)

BigT said:


> Could be from the isolator valve, it's not providing much to the loader valve?


But what would be stopping it? I took the valve off and took it apart. Saw nothing wrong inside. I did not replace the rings but they looked intact and with out issue. When I use the loader it has power but not enough to lift the weight off the front of the tractor and of course still just creeping up and down very slow. I might just pull the line off to the set of control valves for the loader and see if any debris went through the system and got stuck in there that could be limiting the flow or something. I wonder what the symptoms are if the safety valve blows?


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## Hacke (Feb 22, 2011)

Do you mean the selector valve? The one that points forward under the seat?
If so, can you feel the detents being locked at all three positions?

Could you by any chance have moved the flow control?

Does the tractor have a cab?


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## Zoin (Jun 2, 2021)

Hacke said:


> Do you mean the selector valve? The one that points forward under the seat?
> If so, can you feel the detents being locked at all three positions?
> 
> Could you by any chance have moved the flow control?
> ...


Selector and isolator valve equals the same thing. Yes I have moved the flow control to see what effect it had on it in this state and it made it go slower and yes it does have a cab. Ya I know what you were thinking that maybe my heel hit the control and rotated it but nope no luck.


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## Hacke (Feb 22, 2011)

Zoin said:


> Selector and isolator valve equals the same thing....


Well, you learn something every day...

I asked about the detents, because if the spool is not locked properly in either fully out, or fully in position, the spool may be pushed towards the middle position and the flow will be divided.

Are you adjusting the spool by grabbing the knob directly, no linkage in between?


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## Zoin (Jun 2, 2021)

Hacke said:


> Well, you learn something every day...
> 
> I asked about the detents, because if the spool is not locked properly in either fully out, or fully in position, the spool may be pushed towards the middle position and the flow will be divided.
> 
> Are you adjusting the spool by grabbing the knob directly, no linkage in between?


Yes Hacke grabbing it directly and it is going through it's normal full positions.
Here is a pic of a valve that I pulled from one for sale on Ebay.


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## Zoin (Jun 2, 2021)

Hey guys by the way I appreciate the suggestions and questions. I am going away for the weekend to the cottage so I won't be working on it but if the internet is working up there I will be replying to you.


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## Hacke (Feb 22, 2011)

Zoin said:


> Yes Hacke grabbing it directly and it is going through it's normal full positions....


When you had the valve apart, did you check the spring and detent ball/plunger?
Do you feel the three positions click in place?
Is the spool still in its "clicked in" position when the hydraulics/lift have been used, and the problem occurs?


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## Hacke (Feb 22, 2011)

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(4600) - 3 CYL AG TRACTOR ALL PURPOSE (1/75-12/81) (05J01) - SELECTOR VALVE, ACCESSORY, 2600, 3600, 3900, 4100, 4600, 231, 531, 233 & 333 New Holland Agriculture







avspare.com





Here is a screenshot showing the detents, ball and spring.
(It does not show the screw under the spring.)


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## Zoin (Jun 2, 2021)

Yes you actually have to remove the set screw which allows the spring and ball bearing to be removed to disassemble it. It was locking in its proper place.


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## Zoin (Jun 2, 2021)

Further more I slowly moved the plunger while trying it. Made no difference. Well what it did was when I moved the lever for the loader the rear arms lifted with the plunger partially pushed.


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## Zoin (Jun 2, 2021)

Update. Messed up my back so am doing things a bit slow. Anyway I got in it today and very slowly moved the plunger on the hydraulic valve and it certainly can make the hydraulics go faster but still not what they should be. As much as the valve looked decent inside I think it may be the problem. I will now look for options as to what replacement valve I install on it.
Here are some pictures of what I have here.


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