# 1991 ford 1720 hydraulics



## Brad Walker (Aug 2, 2020)

hi all! new member. i recently picked up a 1991 ford 1720 w/ 7308 loader for brush hoggin and movin dirt, etc. picked it up pretty cheap (i think) needed some lovin. problem i am having is: i cant use the fel unless the 3ph is dead headed all the way up. what should i be looking at? i am fairly mechanically inclined but i dont know tractors. this is my first. any help is appreciated. thanks in advance


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## Fedup (Feb 25, 2014)

First thing I would look for would be the lines connecting the loader valve to the tractor. There should be three lines from the valve to a square block somewhere on the lower right side of the tractor. The three ports on the block may be labeled but they may not. The one closest to the supply line from the pump should be the pressure out port. The other two will be pressure in and sump return ports. If these lines are attached incorrectly it will certainly affect the operation of the loader as well as other hydraulic functions. There is a spool in that block with a slot in the end. It can be rotated with a screwdriver. It will turn maybe a half turn or so one way or the other. This controls oil flow between the tractor and the loader valve. In one position both the loader and the other hydraulics are all operational. In the other direction the loader valve is not. It should always be turned fully one way or the other. You might check that spool to make sure it's not accidentally turned to some point between the stops. That would also have adverse effects.


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## Brad Walker (Aug 2, 2020)

2 lines on the diverter manifold. Output and return. 3rd (input) is capped. Where should that line be coming from? Spool is turned to the left. When i turned it to the right the tractor would barely run.


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## Fedup (Feb 25, 2014)

Spool is probably right then, but you have at least one problem, maybe more, Lack of a third line says your loader valve is not plumbed correctly to have the return flow routed through the three point. There should be three ports and three lines. Someone may have changed the valve at some point and used one that "fit" but doesn't "work". I would start there. Examine/research the valve to figure out if it's simply hooked up wrong, or just plain wrong.


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## Brad Walker (Aug 2, 2020)

the tractor didnt originally come with the loader. the guy i bought it from put the loader on last year. valve (Prince) came with the loader. currently the manifold pressure inlet port is capped, pressure outlet goes to the PB port on the valve, return is correct (valve port marked T). spool is pointed to 1 o'clock. with the research i have done, it looks like the manifold pressure inlet port is supposed to go to the valve port "P". that port is a lot smaller than the rest. is it for pressure returning from the valve to the manifold? should the manifold spool be turned to 11 o'clock. when i do that the tractor bogs down so bad that it is barely running. is that because there is constant pressure going to the valve ? is there a relief valve stuck somewhere?


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## Fedup (Feb 25, 2014)

Right now I'm as confused about what you have as you are. I THINK based on what you've stated so far the spool in the manifold is probably turned the wrong way. What you have is a mess. To begin with it sounds like the loader valve is plumbed backwards. 

The manifold pressure out port should connect to the loader valve pressure in port. It's usually the one closest to the relief valve. The manifold pressure in port should connect to the loader valve PB port. The tank or sump ports are probably correct at this point. You need to confirm that the loader valve PB port is in fact what you think it is. Typically that port will have what appears to be an adapter fitting threaded into it and your hose/line fitting threads into that. Once you have those three lines in place(correctly)and the manifold spool in its present position I believe your three point will work but not the loader. Rotate the spool to the other position and the loader will operate as it should and when the loader valves are in neutral the three point will operate as well.


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## Brad Walker (Aug 2, 2020)

Now it makes sense. Thats what i needed. What lines go where. Manifold pressure out goes to valve inlet port ("P" on the valve). Manifold pressure inlet comes from valve PB port. Manifold return from valve return ("T" on the valve). So the loader takes president. When not in use pb port sends fluid to the 3ph. If i didnt have a loader all manifold ports would be plugged, sending fluid direcly to the 3 ph. Hence the spool on the manifold. I need to get a line made up. Will let you know what happens. Still curious why the inlet port is the smallest port on the valve.


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## Fedup (Feb 25, 2014)

How small is the port in question? Ports on the manifold are 3/8 pipe. Is your valve port smaller than that? Most valves have at least that size or larger.


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## Brad Walker (Aug 2, 2020)

It looks to be 1/4". A1,2 b1,2 are 3/8". PB and return are larger. . The diagram i have for the valve shows a larger port with a cap on the side. I have to look to see if the port might be on the side.


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## Brad Walker (Aug 2, 2020)

valve inlet port was on the side. hydraulics are all good now. everything functions properly. now its on to the little stuff. tie rod ends, lights, etc.
thanks for the help


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