Need review on hydraulic hail Mary.

[amashinga]

I recently bought an older compact tractor. The engine is fine, the hydraulics have been giving me grief. I replaced the control valve, but still had some significant leak by. I decided to do a full diagnostic check. First thing I did was popped the screen filter. A LOT of metal shavings, hmmm that cannot be good. It did not look like it had ever been cleaned out. I removed a couple of cylinders, and took off the pistons etc. This is what I had once things were apart.

except, on one the o-ring and backup is missing, as well as the seal on the main piston. There is also scoring and obvious wear on all the pistons

So this is my plan of action, I was hoping some of the very knowledgeable folks here could tell me if I am on the wrong track, or if I should do something else.

1. Pull and disassemble all the hydraulic components on the FEL
2. Replace seals and cylinders If I can identify them
3. Drain all the fluid from the tractor and flush all the sediment I can
(what should I use to flush the gearbox with ?)
4. Replace any other parts too damaged to re-use, cylinders etc
5. Re-assemble
6. Pray I dont have to replace the pump

The parts that I dont like on this plan. The pump is not flushed and inspected, and the 3 point hydraulics are left alone. Should I be pulling the whole lot apart, and how easy is it to determine wear on the pump ?. I dont know if I could even find a replacement pump for a ford 1100.

Any help appreciated, or if you need more info, just ask, and I will go look it up.

Thanks
Bruce.

 

[Wayne County Hose]

Bruce,

Before you go tearing everything apart, why don't you find out exactly what is wrong first? Tell us exactly what works fine and what doesn't. Give us more details. You could rebuild 95% of your hydraulics and still not have satisfactory performance.

Aluminum pistons always have scoring on them as they take the abuse rather than the cylinder wall. Your piston looks okay to me.

 

[KJM]

I agree. The piston looks fine (you should see mine!). If I were you, I'd replace the seals (since you have them in pieces already) - the seals shouldn't be too expensive. Then I'd buy a cheap pressure gauge and whack it on a Tee off the loader control valve. I have one permanently set on the lift side of the loader arms (so I can get a "weight" for the bucket). Run the loader up (in my case, since I have the gauge on the lift side) and when it is fully extended you have the pressure - check it is OK. On my B7100, I needed to adjust the relief valve - it was significantly under pressured.

Checking flow, the other variable, is (so far as I know) an expensive exercise. Flow gauges aren't cheap! The pressure gauge I got for $AU5 (a glycerine filled 2300psi job - very nice).

Not having a seal on the piston should nicely fit the "significant leak by" description!

/Kevin

 

[amashinga]

Wayne, Kevin.

Thanks for the responses guys. Short answer as to what is wrong:

1. The metal and crud I cleaned out of my screen scared me, and I want to get rid of as much as I can.

2. Both the lift and bucket cylinders were sinking under load, but I did not check each one separately. It could be one, it could be both on each of the lift arms or bucket.

3. Its a minor irritation, but when the lift arms are fully extended and the relief valve goes, the bucket starts tilting slightly. I may have to live with that if it is the control valve. I will be happy if I sort out 1 and 2

Bruce.

 

[J_J]

Lift arms cylinders and bucket cylinders will leak down, but some more than others. There are many reasons for this. Cheap valves, old valves, bad seals, o-rings worn out or disintegrated cylinders components worn, etc. Did you test the cylinders? Did you replace the valve with a new valve? You should realize that with all your repair, the lift arms and bucket may still leak down, because of the tolerances on some of the valves. Zero leak down is hard to achieve. You could put pilot operated check valves after your control valve.

 

[john_bud]

I'd put new backups and o-rings in. They are CHEAP cheap cheap like a box of birds!

Would a "quad ring" be a better sealing solution (Wayne, whadda ya think?).

The control valve may also have a couple bad o-rings that you can replace and help the performance.


JJ is right on with the LOCK valve. not check valve. You can get them for 75 bucks and would need 2. One for the boom lift and one for the curl.

HYDRAULIC LOCK VALVE
Brand new PRINCE double pilot-operated lock valve designed to lock a cylinder in place when control valve is in the neutral position. Also acts as a safety device to prevent cylinder movement when pump is inactive and valve is accidentally operated. Pilot-operated lock valves may chatter when used in cylinder circuits with heavy loads. A restricting orifice can be plumbed into the hydraulic line to reduce this problem.

Burden Sales Surplus Center Item Detail

The problem with a lock valve on the loader boom lift is it will stop the FLOAT operation dead. Float is passive, and a lock needs pressure to operate.

 

[Wayne County Hose]

Wayne, Kevin.

Thanks for the responses guys. Short answer as to what is wrong:

1. The metal and crud I cleaned out of my screen scared me, and I want to get rid of as much as I can.

Probably wasn't cleaned in a long time so this is normal

2. Both the lift and bucket cylinders were sinking under load, but I did not check each one separately. It could be one, it could be both on each of the lift arms or bucket.

Could be the cylinder seals or the valve or both. You would have to isolate and troubleshoot. If it's the valve, either a higher quality valve would be needed or likie JJ suggested, DPOCV's.

3. Its a minor irritation, but when the lift arms are fully extended and the relief valve goes, the bucket starts tilting slightly. I may have to live with that if it is the control valve. I will be happy if I sort out 1 and 2

Bruce.

Quad rings. Hmmm. I never thought of that. I would try them but I hate to try it on a customer's unit and have it come back. On my own stuff, I might give it a shot.

 

[amashinga]

Great advice, a big thanks. Any comments on what I use to flush out as much crud as I can from the gearbox ?

Based on what I have heard so far, this is what I am going to do.

Pull the remaining two cylinders and inspect them (they take 5 minutes each, no big deal)

Change and flush out the hydraulic fluid, replace the seals I removed, plus those that are missing, and any others that show signs of wear. Replace all o rings. If you folks think quad rings are a better option, tell me, I assume the risk.

re-assemble and live with any leak down assuming that actually having seals on the pistons does reduce the current leak down significantly. I appreciate the advice about lock valves, but if it is considered normal to have some degree of leak down, I need to adjust my expectations.

Buy a pressure guage and ensure the relief valve on the tractor is still A-ok

 

[john_bud]

I actually would NOT try to flush out the gear box unless you really really want to invest in it.

If you do, you will need to put it up on jack stands. Drain all the fluid out. Refill with a mix of diesel and paint thinner. 80/20 to 70/30 ratio. Then run it thru the gears while jacked up. No load on the gears, but lots of agitation to the fluid. Then after a while in each gear (10 min or so), shut down the engine, dive under and pull the plug. It will come out in a huge whoosh. When it is done, strain the fluid and do it again. Repeat until it comes out with no chunks. Then let it drip dry overnight and fill with fluid in the morning.

Outside of taking all the gears out of the case and wiping, I have yet to find a better solution.

jb

Forgot to mention. You will want to block off the fluid path to the loader when you do this or you will get the thin fluid in the cylinders. No real harm, the old days used to see hydraulic fluid cut up to 50% with kero for winter operation. BUT they had to flush and replace in the spring with normal fluid.

 

[J_J]

In addition to what JB said above, let me add this.

Did I mention high pressure filters before the loader valve, so as to keep the valve and cylinders from the crud that is already there. It depends how old the hoses are, as to the decision to clean or replace them. Any metal or particles with a density greater than the hydraulic fluid, will settle in the lowest spot, and I would not disturb it unless you are going to throughly give it a good cleaning, which involves a lot of time and materials. Even with all this good stuff you are doing, just expect the cylinders and valves to leak down, unless you go to the extreme and put big bucks into something that you think is worth it. In dealing with old stuff, one can get it to work, or they can totally rebuild it as though it were new. Is this your only tractor, and are you going to depend on it?

Do you have any idea of your pump pressure? With all the stuff you found already, you might not get a good reading, unless you put a hydraulic tester on it, which will put some resistance in the circuit to get a good reading.

 

[amashinga]

OK, I will keep it to a hydraulic fluid change without flushing.

I am making fair progress, except for one cylinder that is pretty close to locked up. I wonder what I will find when I get it open.

Any preferences between ptfe and polyurethane piston seals ?. I seem to be able to get either for this application.

Thanks
Bruce

 

[Wayne County Hose]

OK, I will keep it to a hydraulic fluid change without flushing.

I am making fair progress, except for one cylinder that is pretty close to locked up. I wonder what I will find when I get it open.

Any preferences between ptfe and polyurethane piston seals ?. I seem to be able to get either for this application.

Thanks
Bruce

polyurethane

 

[Willl]

3. Its a minor irritation, but when the lift arms are fully extended and the relief valve goes, the bucket starts tilting slightly.

This almost sounds like a cylinder miss match. Are both left and right cylinders identicle ?

 

[amashinga]

They are, but it is the tilt cylinder that is partially locked, so I think the chances are good that when I resolve that issue, I resolve the creeping issue too.

What I mean by partially locked is that the cylinder will move, but I have to use a lot of strength to get it to move, even though all the fluid is drained out. Pretty much I have to put a bar through both ends and operate it like a double handled pump to be able to move it. When it moves, it jerks, so I know something is wrong there.

 

[Wayne County Hose]

What I mean by partially locked is that the cylinder will move, but I have to use a lot of strength to get it to move, even though all the fluid is drained out. Pretty much I have to put a bar through both ends and operate it like a double handled pump to be able to move it. When it moves, it jerks, so I know something is wrong there.

Maybe a problem, maybe not. You may take it apart and find everything normal.

 

[amashinga]

Next steps, and further questions

I have popped all the cylinders. 2 of the pistons look ok, one has a bad score and I may decide to replace it, and then the one that was sticking looks like it got used in a game of street hockey.

The seals show varying signs of wear but given that they are all really cheap, I think I will just replace them all anyway.

So here come the questions.

I cannot find a supplier for pistons. Is this something that you usually just take along to a machine shop, or can someone point me to a website ?.

The second and longer question, the seal catalogue I was looking at has tolerances listed for the OD of the piston as well as the bore diameter. Assuming a bore of 2.5 they usually indicate a piston OD of 0.004 below this. My pistons seem to be more like 1.490 even in areas that the milling marks are still visible, ie limited wear. Is 0.01 an acceptable tolerance in this application ?

 

[Wayne County Hose]

I cannot find a supplier for pistons. Is this something that you usually just take along to a machine shop, or can someone point me to a website ?.

Hercules Sealing Products You want the Cylinders & Repair Parts catalog.

The second and longer question, the seal catalogue I was looking at has tolerances listed for the OD of the piston as well as the bore diameter. Assuming a bore of 2.5 they usually indicate a piston OD of 0.004 below this. My pistons seem to be more like 1.490 even in areas that the milling marks are still visible, ie limited wear. Is 0.01 an acceptable tolerance in this application ?

Don't worry about it. But, if you are going to get 1 piston, you might as well get them both.

 

[amashinga]

Thank you Andy. I live in Canada but if it is in any way worth your while to ship the items and its something you deal in, just send me a PM.

 

[Wayne County Hose]

I don't stock this stuff and I would need your old ones in order to measure them. I would suggest locating a local hyd shop. Otherwise, you could ship them to me. Another suggestion would be to look in the Hercules catalog for a pair of cylinders that are close to the same measurements and go with new. By the time you buy pistons and seals, a new cylinder isn't much more and you have new cylinders instead of old junk.

 

[john_bud]

H&D Distributors, Inc. Your Complete Source for Seals

if you follow the link and down load the catalog you will become an expert. It's like 10 meg and includes pictures. Prices are ok, delivery in US is good. But, the understanding you get from comparing the parts in hand to the pictures is priceless.

jb