Tilt Leaking Off

[subford]

I have a 1999 873F that the tilt will leak off very fast in one direction but not the other. Does anyone have a hydraulic diagram of the this system that does not have foot control that you can send me. Email address below. I have a 873 service manual but both hydraulic diagrams in it are for foot control. This system has AHC. You can tilt the bucket forward (extending the cylinders) with the front wheels off the ground and it will not leak off. So it is not the cylinders. When you pick up something you have to keep tilting it back to keep from losing the load. The lift cylinders work fine.

 

[Fishfiles]

From what you say , you can not rule out a problem inside the cylinder , when you push the bucket down on the ground and lift the machine's wheels off the ground you are pushing the piston against the rod , when you lift something off the ground in the bucket then the piston is pushing away from the rod , so if the nut on the end of the rod has loosened up then oil will pass around the threaded end of the rod , the piston nut coming loose is a very common thing that happens -------------------- I know you think the cylinders are fine and it's not the cylinders , but that is the most probable place to start ----- I'l tell you how you can check it without disassembling the cylinder , take the bucket off , disconnect the tilt cylinders rod ends and push and pull the rod in and out , you may or not feel the clang depending on how loose the nut is ----------

 

[Jyuma]

From what you say , you can not rule out a problem inside the cylinder , when you push the bucket down on the ground and lift the machine's wheels off the ground you are pushing the piston against the rod , when you lift something off the ground in the bucket then the piston is pushing away from the rod , so if the nut on the end of the rod has loosened up then oil will pass around the threaded end of the rod , the piston nut coming loose is a very common thing that happens -------------------- I know you think the cylinders are fine and it's not the cylinders , but that is the most probable place to start ----- I'l tell you how you can check it without disassembling the cylinder , take the bucket off , disconnect the tilt cylinders rod ends and push and pull the rod in and out , you may or not feel the clang depending on how loose the nut is ----------

Fishfiles... please excuse my ignorance but I'm curious as to the reason why direction would matter. I recently rebuilt my lift cylinders and the internal end of the rod consisted of a shoulder, a nut and two steel washers with the piston (black) and nylon like washers (orange) squeezed between them.
In the photo below I have shown the pieces in their correct order but before the nut was torqued down, which is why you see the large space between the right side steel washer and the shoulder on the rod.

If hydraulic pressure is supplied from the nut side or the rod side why would it make any difference to the piston's sealing ability? Pressure applied from the nut side would tend to squeeze the piston between the shoulder on the rod and the washer under the nut... conversely, pressure from the rod side would tend to squeeze the piston between the nut on the end of the rod and the washer on the shoulder side. Why would it seal any better in one direction over the other?
I don't doubt your conclusion, I am merely trying to understand the process.
Thanks

 

[subford]

Fishfiles... please excuse my ignorance but I'm curious as to the reason why direction would matter. I recently rebuilt my lift cylinders and the internal end of the rod consisted of a shoulder, a nut and two steel washers with the piston (black) and nylon like washers (orange) squeezed between them.
In the photo below I have shown the pieces in their correct order but before the nut was torqued down, which is why you see the large space between the right side steel washer and the shoulder on the rod.

If hydraulic pressure is supplied from the nut side or the rod side why would it make any difference to the piston's sealing ability? Pressure applied from the nut side would tend to squeeze the piston between the shoulder on the rod and the washer under the nut... conversely, pressure from the rod side would tend to squeeze the piston between the nut on the end of the rod and the washer on the shoulder side. Why would it seal any better in one direction over the other?
I don't doubt your conclusion, I am merely trying to understand the process.
Thanks

I know the right cylinder nut is OK as we just had that cylinder apart and it was doing this before it was taken apart.

 

[jerry]

I know the right cylinder nut is OK as we just had that cylinder apart and it was doing this before it was taken apart.

Put a load in the bucket, with it sitting flat on the ground disconnect the lines at the cylinders and plug the rod end cylinder ports. If it drifts down when you lift it now, it has to be bypassing the piston. certain to be a mess but it will eliminate the cyls at least.

 

[Fishfiles]

Fishfiles... please excuse my ignorance but I'm curious as to the reason why direction would matter. I recently rebuilt my lift cylinders and the internal end of the rod consisted of a shoulder, a nut and two steel washers with the piston (black) and nylon like washers (orange) squeezed between them.
In the photo below I have shown the pieces in their correct order but before the nut was torqued down, which is why you see the large space between the right side steel washer and the shoulder on the rod.

If hydraulic pressure is supplied from the nut side or the rod side why would it make any difference to the piston's sealing ability? Pressure applied from the nut side would tend to squeeze the piston between the shoulder on the rod and the washer under the nut... conversely, pressure from the rod side would tend to squeeze the piston between the nut on the end of the rod and the washer on the shoulder side. Why would it seal any better in one direction over the other?
I don't doubt your conclusion, I am merely trying to understand the process.
Thanks

if the nut holding the piston to the rod is loose when you put pressure to the port on the back side of the casing ( which would extend the rod and make the bucket tilt down ) the nut is being forced against the shoulder of the rod which causes it to seal off any oil that would by pass thru the bore of the piston around the threads , when you apply pressure to the port on the chrome rod side it will push the piston back away from the shoulder and let oil by pass thru the bore of the piston around the threads , this would be in the bucket up mode and would let the bucket creep down , it would look just like your picture when the pressure was applied to tilt up ------------------you see in the pic you posted that little o ring , that is suppose to go over the end of the rod and seal between the piston and the shoulder , not all seal kits have that o ring , and it may not have been on the rod when you took it apart --------------- do you see what I am trying to explain now , it is a very common problem and may not be what your problem is , but it is the most likely and easiest to check ,

 

[Jyuma]

if the nut holding the piston to the rod is loose when you put pressure to the port on the back side of the casing ( which would extend the rod and make the bucket tilt down ) the nut is being forced against the shoulder of the rod which causes it to seal off any oil that would by pass thru the bore of the piston around the threads , when you apply pressure to the port on the chrome rod side it will push the piston back away from the shoulder and let oil by pass thru the bore of the piston around the threads , this would be in the bucket up mode and would let the bucket creep down , it would look just like your picture when the pressure was applied to tilt up ------------------you see in the pic you posted that little o ring , that is suppose to go over the end of the rod and seal between the piston and the shoulder , not all seal kits have that o ring , and it may not have been on the rod when you took it apart --------------- do you see what I am trying to explain now , it is a very common problem and may not be what your problem is , but it is the most likely and easiest to check ,

i.c. Thanks