Cylinder internal leak?

[sony224422]

I figured a new thread would gather more interest- I have my 1964 ford 4000 fel and backhoe, and am having a weak bucket curl on the backhoe. I put a gauge on the test port and am able to get 2000 psi (relief setting).

I can put the outriggers down and lift the rear of the tractor until the cylinders bottom out and they will hit 2000 psi. I can put the boom down and lift the rear of the tractor off the outriggers and hit 2000 psi when it bottoms out too. I can swing left and right with no reason to think anything is wrong with that either. The pull on the arm seems like it is strong enough, though I’m not sure if I can test it other than it will hit 2000 psi I believe. I plan on testing to see if it will pull the tractor backwards with the out riggers up.
The curl is where I have issues. It will curl, and while there is no load on it, like in the air, it will curl up and hit between 500-700 psi until it bottoms out and then it will shoot to 2000 psi. When it’s in the ground, and I go to curl, it will hit 2000 psi but seems like there is no strength. I can’t scoop a bucket of dirt, or really even drag the teeth through the dirt.

The front end loader easily lifts the front off the ground.

The loader valve is brand new from surplus center, with a power beyond. The loader valve is set to 2000 psi from the factory, supposedly, but I haven’t tested that but don’t think I need to. The backhoe valve is set to 2000 psi too from what I can test and see.

My thought is that I need to take a line off the curl cylinder and see if the fluid is bypassing internally when the lever is worked. Is there anything I should check?

 

[ROUSTABOUT]

I wouldn't have spent all that time checking. Just pull a line off on one side of piston and apply real pressure to the other side of piston. If fluid comes out of cylinder, there's your problem. Get a good flash light and do a visual of the cylinder bore. Make sure it's smooth. Check your rod for any nicks and take care of those. I use a fine file and sand paper. Then take piston off rod and take cylinder cap together to a hydraulic shop and they can match up some parts to fit what you have. That will be a lot cheaper than getting the correct kit somewhere. Basically you get the same kit from a dealer, but somebody in the chain makes a few hundred off you. I've worked at a few dealerships.

 

[TractorTech]

Agree with Roustabout that you found the problem when circuit tested good. The cylinders are pretty simple on those older backhoes. Chevron packing is the norm and a shop can put together cheap OR you can search for kits that range all over the price range if you don’t have a local shop.

 

[Dave M7040]

The attached procedure will help your thoroughly check out your cylinder. A cylinder can bulge in the middle. In this situation the piston seal will not leak at the end of the strokes.
Dave M7040

 

[sony224422]

I really appreciate the help and the troubleshooting. I switched lines around just to test the control valves (I have the test manuals and they suggest it and it’s easy enough) and then took a line off the cylinder. I did not get what I thought I would, a little if any fluid really came out. It did not gush out.

I am wondering if it’s just not as strong as I think it would be. I’ve only ever run mini excavators, and they were decently powerful. I think maybe my technique and machine size are just smaller and less powerful than I’d thought they’d be.

 

[TractorTech]

Interesting. Regardless of age and your experience with other machines, it may not be what you have experienced on newer machines, but it should curl and scoop dirt.
What model is the backhoe or do you have some pictures of it?

 

[LD1]

Wouldnt hurt to test the cylinder. but if you are getting full system pressure I am gonna assume the machine is just weaker than you expect compared to a mini-ex.

I too am curious as to what model the hoe is....and maybe some pics? Maybe the bucket is too big to be effective in the material you are digging, or someones home-brew repair in the past and put on a different (smaller) cylinder.

Also, some of them old hoe's have different pin holes on the bucket for different leverage and range of motion. One will give more articulation but less power, the other will give more power but less articulation

 

[sony224422]

It’s a 1964 ford 4000 (4140) with the 20 gpm front hydraulic pump. New loader valve with power beyond to the hoe. Ford 712 loader and 723 hoe

 

[TractorTech]

Thanks for the pictures. As LD1 said, there are different holes for different reasons.
Have you tried to to pin the dogbone link onto the bucket back hole? This would give you more leverage.

 

[ROUSTABOUT]

If you got any fluid, you may not have been in the exact bad spot. I would do it with piston near center of travel. That old hoe should be a hoss about digging. I'm in Arkansas and we use machines like that on the regular. It should hang with a new one. I'm saying cylinder needs a packing.

 

[LD1]

I'd try the other pin hole. But Im guessing is a combination of hard ground (I see alot of roots and rocks in one pic), and improper technique.

Keep practicing

 

[nyone]

My thought is that I need to take a line off the curl cylinder and see if the fluid is bypassing internally when the lever is worked. Is there anything I should check

This is how I would check it. If you still have a problem boost the pressure.

 

[LD1]

This is how I would check it. If you still have a problem boost the pressure.

2000psi should be more than enough. This is older equipment. Start boosting pressure when that isnt the problem is asking for more issues IMO

 

[TractorTech]

2000psi should be more than enough. This is older equipment. Start boosting pressure when that isnt the problem is asking for more issues IMO

Agree!

 

[nyone]

2000psi should be more than enough. This is older equipment. Start boosting pressure when that isnt the problem is asking for more issues IMO

So if it's not an internal leak then what do you suspect it to be? Typicaly a internal leak wouldnt allow proper pressure to be built. Did you try a pressure hold test when you checked pressures?

The pump can obviously build pressure so I wouldnt suspect that. Becids those two things the only thing left is the valve body..but again its building 2000psi.

 

[Tinhack]

You have a kink in the curl return metal line. When pressure is applied to the extend side, the oil on the rod side has to move freely through that tube. Could be that kink is costing you power.

 

[LD1]

So if it's not an internal leak then what do you suspect it to be? Typicaly a internal leak wouldnt allow proper pressure to be built. Did you try a pressure hold test when you checked pressures?

The pump can obviously build pressure so I wouldnt suspect that. Becids those two things the only thing left is the valve body..but again its building 2000psi.

No idea what the problem is. We haven't got enough to information out of the OP yet.
No idea where he tested pressure it....so can't rule out the valve or the cylinder at this point. Also can't rule out that it's just operator error

But what we can say is that at 2000psi, it doesn't warrant messing with trying to boost pressure

 

[sony224422]

Thanks everyone! I have some more things to go off of, but to answer a few of the questions-

I have a gauge on the side of the valve, in the test port that the book recommends using to test pressure. I am able to get the 2000 PSI when the cylinders bottom out or have stress against them (like when it won't curl anymore)

I am working on switching the pin location on the bucket, it is nice and rusted in the bushing so I will try pushing it out or using some heat and hopefully will be able to switch it

I tested that cylinder by taking the line off at the metal hose that is kinked, I actually didn't even notice that. I went out and looked at it, and it is a little kinked so I will see what I can do to straighten it out. When working that piston at full lock it did not really squirt any fluid like I thought it would. I did try putting the bucket in dirt without it bottomed out and doing the same thing with the same results of not really anything coming out.

I do question the hose integrity, but I don't know if that would cause my issues. The adapters are strange for this, but someone really cobbled the hoses and fittings together. My plan is to get some adapters and new hoses just to be sure. Some have 2-3 adapters.

Over the summer, when I was figuring out why it wouldn't build any pressure, I flow tested the pump by itself with a flow meter from my neighbor. I was able to get about 15-17 gpm at 2000 psi, and even brought the pump to a hydraulic shop and they looked internally and thought it wasn't bad, though someone had rebuilt it at one point. My pump is on the lower end of my radar, for now.

I also have a new filter coming, I am curious if the filter I have on there isn't rated for the GPM I need, so I found one that is for sure, and I will feel better about that.

I do need to practice, 4 stick is definitely different than a joystick for digging, and the ground is rather hard. I can't tell if the rocks I'm going for are ledge or bigger than what the hoe can handle, but the roots are from a tree that was taken down and ground up, I was removing the large roots from around the stump.

 

[LD1]

A restriction in the hose....should effect its power as long as its at least flowing

Obviously a total blockage would be no power at all....but also no movement.

As long as the bucket moves....a restriction is only gonna slow it down. NOT make it have less power.

I think alot of this is just practice and technique. Unless you are pulling stumps.....dont try digging so much with bucket power alone.

For example, if digging a hole or trench....use the bucket to control the angle of attack of the teeth.....but 90% of the digging comes from the dipper/crowd.

As you reach the hoe out and penetrate the teeth ~4" in the ground....you crowd in while raising the boom at the same time to control the depth and peel out a ~4" slice. Just use the bucket to control the teeth angle.....and then when the bucket is full from crowding in......the bucket curls up to not spill the scoop.

Practice.

If possible.....have someone video your attempt at digging or using the hoe and share the video. We arent judgmental here.....there was a time when I had never ran a hoe before. This is about teaching/learning, so dont be ashamed if you arent doing something properly.

 

[TractorTech]

The kink in the line would cause it to be slower, but you should still be able to dig through. As LD1 pointed out, it is the angle of attack and using the dipper/crowd that is the intent with the Ford backhoes. It is shaped with a long bottom for that reason, not shaped like an ice cream scoop.