FEL hydraulics have failed

[zing]

So I got a few hours to poke around with the tractor and try some of the suggestions that you guys made.

First is oldnslo's test. I had my 5 foot Woods bushhog on the 3pt, so it wasn't a lot of weight but at least a couple of hundred lbs. I pulled the lever to raise the loader and then raised the 3pt, came up no problem. Tried the same with the bucket curl lever and once again the 3pt raised no problem. Presumably this means there are two hydraulic pumps but I have ony found one and I still don't have my book, so I have no official confirmation.

I did some looking at the hydraulics. Up front I have a hydraulic pump that is belt driven off the same belt as the alternator runs on.

Fluid supply comes from the center bottom of tractor and enters pump on the right hand side.

Fluid exits on pump's left and heads to rear of tractor. Splits about halfway back and goes under the axle on both sides of the tractor.

The left rear lines feed my rear hydraulics, which I have never used. The right rear lines go to the area that my loader supply hoses come from, but I can't see much because it is all covered by a casing. They also feed this big canister, which I guess is my hydraulic filter. Can anyone confirm this is the hyd filter? Is servicing it just a matter of undoing the screw at the bottom and then change a paper filter?

 

[zing]

I also spent some time with the loader valve. Couldn't do much with the hoses connected because they were in the way so I started with removing the 4 hoses that go to the FEL cylinders. Holy Hannah, they were tight! Could not move them until I used a pair of 3 foot cheaters to get some extra leverage. I felt like the janitor on the last day of school with those giant bolt cutters removing all of the locks left on the lockers.

The first thing I tried was the relief. It came out easy. The o-rings looked fine, but other than that I had no idea what I should be looking for. It is just a post the goes into a hole. Nothing noteable about it or the hole. Is there something that I should be looking for there?

Next was the spring assembly and valve body. The spring assemblies were both loaded with crud, but that was separate from the internal workings of the valve and the action of the levers were both fine even with the crud in the spring. I don't have a clean workspace in my equipment shed, so I left it as it is and will probably take the whole valve to the city and clean those up where I have a suitable work area.

The valve internals seemed clean and the o-rings were fine. I pulled both shafts out, and inspected them and their housing and saw nothing that looked bad. I don't know what I should be looking for though, so it is entirely possible that there was something that I missed. Anything in particular that I should look for when I pull this apart the next time?

My next step was going to be the load check valves, but they were painted on and did not move with a regular socket. Before I had an opportunity to put any effort into removing them, the kids came down looking for me to start the BBQ and get them some supper. I reconnected the 4 loader hoses and started the tractor, no leaks. Tested the loader and bucket and still absolutely nothing happened for up or down on loader ams or bucket.

Next step I guesws is to get that hyd filter cleaned or replaced, and try to get a look at the load check valves. I may also look into a 3000 PSI test guage the next time I am in the city, if they can be purchased or rented for a reasonable price.

Any suggestions or advice gladly accepted if there is something else I should be doing or looking for. Thanks for your help up to this point.

 

[SSdoxie]

Don't worry about the load checks, a failure there would NOT cause complete loss of function. A load check could be completely removed and loader would still go up & down. They are there to hold the load if you lift part way stop then try lift some more, then the pressure on the cylinder with load on it keeps the load check closed until pressure on the pump side builds to same or greater before the check opens to let fluid into the work port. This keeps the loader from dropping when you first move the lever.
That relief valve plug is just a stem block, there is another relief somewhere between pump and the control valve. Only inspection of the plug/stem is to see if the slightly tapered end is fitting tight to the seat in the valve and the smaller O-ring is not torn or pitted.

It's not real clear in the pictures; I see 2 steel lines coming off 1 side of the pump, is there another line on the opposite side of the pump. If so the 2 lines on the same side would be 2 outlets, meaning it is a tandem (2 section) pump. Quite possibly 1 section for 3 pt. the other for loader and/or rear remote since you mentioned a "switch" or lever close to where the loader valve lines come out of the tractor.

 

[zing]

Don't worry about the load checks, a failure there would NOT cause complete loss of function. A load check could be completely removed and loader would still go up & down. They are there to hold the load if you lift part way stop then try lift some more, then the pressure on the cylinder with load on it keeps the load check closed until pressure on the pump side builds to same or greater before the check opens to let fluid into the work port. This keeps the loader from dropping when you first move the lever.
That relief valve plug is just a stem block, there is another relief somewhere between pump and the control valve. Only inspection of the plug/stem is to see if the slightly tapered end is fitting tight to the seat in the valve and the smaller O-ring is not torn or pitted.

It's not real clear in the pictures; I see 2 steel lines coming off 1 side of the pump, is there another line on the opposite side of the pump. If so the 2 lines on the same side would be 2 outlets, meaning it is a tandem (2 section) pump. Quite possibly 1 section for 3 pt. the other for loader and/or rear remote since you mentioned a "switch" or lever close to where the loader valve lines come out of the tractor.

I am quite sure the two steel lines are outlets, and that the inlet is the thicker line on the other side. I will look tomorrow and get a better confirmation though. With a two section pump, is it possible that one section has failed and the other section still works? Just guessing, but if it is the pump and I have to replace it I would bet that a two section pump will be more expensive than a single section one.

 

[J_J]

This process of trouble shooting and elimination of causes should have not taken this long.

You can not even tell me if there is pressure/flow in the valve.

Have you determined flow through the FEL valve.

Some pumps are two section, ans one will feed the steering and attachments.

Hydraulics:
Type: open center
Pressure: 2550 psi [175.8 bar]
Valves: 1 to 3
Total flow: 7.7 gpm [29.1 lpm]
15.3 gpm [57.9 lpm] (tandem)
Steering flow: 7.7 gpm [29.1 lpm]
Steering press.: 1500 psi [103.4 bar]

Can you verify flow into the valve and flow out of the valve.

If the out port is blocked for some reason, you will have no flow.

If you have flow into the FEL valve and flow out of the valve , then there is no apparent reason that the the work ports would not have flow if the spools are moving as they should.

Seems like a lot of people will wait a long time trouble shooting and not use a gage.

There should be one on every tractor or anything hyd. It simply supplies answers to some questions.

A relief valve should have a spring on the closing element to keep the path closed until the pressure limit is met.

Some valves have a relief port, and on some valves, a no relief valve is called for.

On a FEL valve I would think a relief valve is necessary...

 

[oldnslo]

Zing,
I suspect the front belt driven pump is for your power steering.

Yes that appears to be the filter housing. Unscrewing the bowl will provide access to the filter element.

Rear two section pump: pretty rare for one section to totally fail and the other still work fine especially when from your piping description the front pump feeds the FEL & the rear feeds the 3PH.

Without having some schematic or circuit diagram my best guess would be that there is a valve somewhere diverting the flow away from the FEL valve. I seriously doubt a relief valve since from the initial failure the loader raised part way. Then when you went to move it again nothing happened. I see no reason the FEL would cause this failure but again without knowing the circuit I am only guessing.

JJ is correct in that somehow you need to determine if you are getting flow to the FEL valve & then see if you get flow under pressure. Not an easy process since this requires a flow meter be installed in the inlet line to the FEL valve. Just placing the hose in a bucket only shows that you have flow under no load.

 

[J_J]

He could use a needle valve and gage and slowly close down the needle valve to check pressure.

 

[oldnslo]

He could use a needle valve and gage and slowly close down the needle valve to check pressure.

yes you can use this procedure but it causes me concern for a couple of reasons.
1) How large is your reservoir Vs pump flow? I.e. how quick will you drain the reservoir. On these smaller tractors pump flow can drain the reservoir in a minute or two. You can possibly loop the hose back to the tank but then it becomes more difficult to see if you flow.

2) If needle valve is closed to quickly there is potentially no relief valve in the circuit so the weak link breaks. Depending on the style of needle valve and flow rate 1/4 to 1/2 turn can be the difference between very little pressure to an Oh Sh*t situation.

my :2cents:

 

[J_J]

You be right.

My mistake, I should have included a relief valve before the needle valve with both hoses to tank.

This would be the type of needle valve I would use.

1/2 NPT 15 GPM PRINCE WFC-800 IN-LINE FLOW CONTROL

 

[zing]

Problem solved, and I am embarassed to say what it was but you guys were great about helping me and so I owe it to you to spill the beans. Besides, it might help someone else someday with the same issue. The problem was a lever with this sticker beside it that I had never paid any attention to before this issue appeared. Picture below.

When the issue appeared I moved the lever to the front and to the back and tested, but I guess I must have neglected to test it with the lever in the middle. I don't understand why the middle position would be required to make the FEL work, since the middle position seems to indicate that the external hydraulics are off (judging by the two X's). I still haven't gotten my tractor manual back from my friend, but when I do I will be reading more about this switch and what it is for.


While I was troubleshooting though, I did get the hydraulic filter replaced. $75 for a filter, that was an unpleasant surprise!! How often do you guys replace that item on on older tractor, as in every how many hours is best practice? At 75 bucks a pop I am willing to bet it is not done with every oil change...

 

[zing]

Another question, for J J or anyone else that has a 3000 PSI pressue tester. When I picked up the new hydraulic filter at the local CAT dealership I asked about buying a pressure tester as well and they had no idea what I was talking about. Mind you, this was the Part department guy, not a tech.

Is a pressure tester something that you can buy off the shelf, or do you have to buy a 3000 or 3500 PSI guage with the little straight end (like this ) , and then also buy a bunch of various fittings that would allow you to connect it to different places in your system? For example a bunch of 1/2 inch fittings to try it at the loader, some smaller ones to try it where the steel tube comes out of the pump, quick connects to test where there is a QC point, etc? Even though I did not use it this time, I can see that it would be useful for narrowing down any future problems, but I don't know where to get one or how to build one. If anyone has a picture of theirs, that would help too. Thanks! :thumbsup:

 

[J_J]

You can buy them, but it is better to build them for about $30

Round up the parts and put it together.

3000 PSI 2.5" LF LM GAUGE

 

[zing]

Ok, i see. I thought it would require a T joint of some kind so that the fluid could still flow through, but only one of those is a T and the other two are just a single end connector, presumably so that you can test pressure at something like the output of a pump or something I guess. I will have to look around on youtube etc and see if I can find some tutorials on hydraulic mechanics.

Thanks again for the help J J, as well as all others who responded with suggestions and advice. :thumbsup:

 

[J_J]

One test rig does the tee thing.

You can eave the tee rig in place, but the plug in gage is only used intermittently for a quick check as the valve is probably in relief.

 

[zing]

One test rig does the tee thing.

You can eave the tee rig in place, but the plug in gage is only used intermittently for a quick check as the valve is probably in relief.

Intestering. Ok, thanks.