# Ford 4500 Backhoe Hydraulics Issues



## plowjockey (Aug 18, 2008)

I have recently aquired a 69' Ford 4500 backhoe.

The backhoe bucket will lift upwards (forward) and down to about 90 degrees, no problem. any further back and it just stops.

The swing arm hydros (2 using a swing chain) moves good, but will only travel from about 10-2 o'clock. It can be moved the rest of the way by hand.

In both cases, there is no strain on the hydro pump. Things just stop.

The rest of the backhoe hyraulics, seem to work pretty well.

Any help appreciated.


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## agmantoo (May 23, 2003)

Have you verified the hydraulic fluid level is correct? Sounds as if the system is starving for hydraulic oil.


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## Ross (May 9, 2002)

Or a plugged filtre maybe.


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## tinknal (May 21, 2004)

I'm wondering if the machine may have been sitting for a long time. Could the interior of the cylinders have become pitted or rusted where there was no fluid?

I doubt it is low fluid if the system doesn't strain.

ETA maybe bad cylinder ram seals?


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## plowjockey (Aug 18, 2008)

tinknal said:


> I'm wondering if the machine may have been sitting for a long time. Could the interior of the cylinders have become pitted or rusted where there was no fluid?
> 
> I doubt it is low fluid if the system doesn't strain.
> 
> ETA maybe bad cylinder ram seals?


It has been sitting for 10 years, but inside a barn. There was just few rust spots on the top crowder cylinder. Overall the cylinders are in great shape.

The previous owner had these problems before the hoe was parked.

We are looking at the valves next.


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## agmantoo (May 23, 2003)

With the issues mentioned it is ovious the hydraulic pressure is low or absent once the cylinders move the distance mentioned. Rust would not be that restrictive to the operating pressure. Rather than dismantle valves get a pressure gauge and mount it in order to observe what is occurring. The fault could be something as simple as a high pressure releif valve with a broken spring.


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## tinknal (May 21, 2004)

agmantoo said:


> Rust would not be that restrictive to the operating pressure.


I agree with what you say, I was thinking more of damage enough to allow bypass of fluid past the seals.


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## Ray (Dec 5, 2002)

*If the hyd. oil is good clean oil and the filter is good. I would pull the valve bank apart and check the spool wear and O ring condition. Usually the spools get worn pretty bad because the Backhoe controls get used more than the other hyd. spools. best wishes, ray *


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## agmantoo (May 23, 2003)

Ray 

I doubt that the valve bank itself has any O rings. It would most likely be just a precision fit. Excess wear IMO would impact the performance but would unlikely be to the point that the movement of the cylinders without doing work would be full stroke. There has to be either a major leak back to the reservoir tank or very little fluid being delivered to the point of use. Possibly the main shaft to the hydraulic pump is sheared. I would like to know the manner the cylinders move (normal or slow) when the cylinders are activated but do not go their normal travel. As I stated before, the pressure of the hydraulic oil at the point of use needs to be measured. 
A modified hydraulic fitting can be mounted between the hose and one of the none functioning cylinders. This fitting can be drilled on one of the flatter surfaces and tapped for a high pressure gage to be installed. This is cheap and provides better insight as to the fault than blindly dismantling various components.


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## plowjockey (Aug 18, 2008)

agmantoo said:


> Ray
> 
> I doubt that the valve bank itself has any O rings. It would most likely be just a precision fit. Excess wear IMO would impact the performance but would unlikely be to the point that the movement of the cylinders without doing work would be full stroke. There has to be either a major leak back to the reservoir tank or very little fluid being delivered to the point of use. Possibly the main shaft to the hydraulic pump is sheared. I would like to know the manner the cylinders move (normal or slow) when the cylinders are activated but do not go their normal travel. As I stated before, the pressure of the hydraulic oil at the point of use needs to be measured.
> A modified hydraulic fitting can be mounted between the hose and one of the none functioning cylinders. This fitting can be drilled on one of the flatter surfaces and tapped for a high pressure gage to be installed. This is cheap and provides better insight as to the fault than blindly dismantling various components.


The cylinders move fine as far as they will travel and I don't suspect pump pressure issues, as the support legs work quickly and the loader will lift the front of the tractor, off the ground in about 2 seconds.

My mechanic (my db) thinks pressure is being leaked into another cylinder and troubleshoot that, but we just rebuilding the whole block, since it has never been done.

The add-in gauge is a good idea that I will pass to him.


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## Ray (Dec 5, 2002)

I guess you thought I ment O rings inside the spools???? well shoot me in the head. ha ha ha I'm certainly not the best hydraulic repairman around, although I've seen enough different brands that tearing some of them apart was quite a learning experience, the way the systems were engineered was fascinating. Some systems I only worked on once, others were in constant failure. Ford backhoe, we had two, longhole rigs we had a couple dozen. I guess we had probably 40 or more different brands of machinery, and manufactures of hydraulic valves, actuators, pumps, hydraulic motors, etc from all over the world. Including the hydraulics on the boom cranes. scoop trams, skid steer, several brands, I've taken many of these things apart , and had to call to get information on how to open several, because no one had ever done it before that was still alive. Some of the intricate engineering that worked and lasted for decades without ever a hint of failure, wow. Some were newer and simply cheep. I defiantly don't type things down correctly if you thought I had o rings inside spool valves. 
There are so many different places o rigs are used though and I'm sure you know where they are. Most valve body stacks are machine fit as o rings would just be a constant problem blowing out, *some I worked on had a high pressure bypass on one side, adjustable, that could become weak, or back off*, and you could stack them in most any configuration you wanted. I still have several banks of valves in oil storage to keep them from disintegrating from being out in the air with moisture etc. 
I bet if you looked at enough different brands in the world out of the thousands or so there are you might find some with o rings in the spool valves somewhere tho so?? never say never if it could be done it probably has, ray 

p.s. I started thinking and counting in my weak old mind and we had easily over a hundred different hydraulic units all from different companies, and I bet over twice that. I worked on many,, just too many hours and days that run together over the years, but I would recognize alot of those if i seen um again. Hard, heavy, dirty old work, good luck on your tractor, ray


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## taylorlambert (Jul 4, 2010)

I have a 3550 Fors hoe a 75 model. My pump is weak but one thing on the old open center hydraulics it wont screech if it runs low on fluid. THe loder wont tilt all the way back and sometimes it wont swing all the way. One thing is the cylinder on the rod en takes up smoe of the space that the fluid would normally take. mine wont dum p all te way if the fluid gets low. Ill gauranteed that some thing small is wrong with it. If mine sits a while it will have large pocktes of air in the swing cylinder and crowd arm. Some times if it sits a week AN i get on it the hoe will flop. I will just wiggle the boom a bit and fill the swing cylinders. Crack a line after running it a bit and see if the fluid is milky from air bubbles to.


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