8N Hydraulic Pump Troubleshooting

lparker73

New User
Good morning,
I have a Ford 8N that I am trying to troubleshoot the hydraulic system. I have read a lot on this forum but can't find answers to a few problems I seem to have.

Here is what I have:
My 3-point hitch works with no attachments or with light implements like a box blade but wont pick up anything heavy like a bush hog. The leak down is pretty slow, it will hold the box blade up for a while after shutting it off.

I removed the inspection plate and did not see/hear a significant amount of oil dripping from the top lid which leads me to think the cylinder/piston are ok. I replaced the relief valve and that did not fix the problem.

Since I had the oil drained down (not empty), I watched the pump with it running and noticed oil and fine bubbles coming out of the top of the valve caps in the chamber. Would this be the cause for my loss of pressure and cause the lift not to pick up heavy implements? I am stuck and don't know if I should just drop the pump and rebuild or keep troubleshooting. Thanks for any help.
 
(quoted from post at 10:45:51 09/10/21) Good morning,
I have a Ford 8N that I am trying to troubleshoot the hydraulic system. I have read a lot on this forum but can't find answers to a few problems I seem to have.

Here is what I have:
My 3-point hitch works with no attachments or with light implements like a box blade but wont pick up anything heavy like a bush hog. The leak down is pretty slow, it will hold the box blade up for a while after shutting it off.

I removed the inspection plate and did not see/hear a significant amount of oil dripping from the top lid which leads me to think the cylinder/piston are ok. I replaced the relief valve and that did not fix the problem.

Since I had the oil drained down (not empty), I watched the pump with it running and noticed oil and fine bubbles coming out of the top of the valve caps in the chamber. Would this be the cause for my loss of pressure and cause the lift not to pick up heavy implements? I am stuck and don't know if I should just drop the pump and rebuild or keep troubleshooting. Thanks for any help.

There should be nothing coming from the caps and yes that is likely your problem.

TOH
 
(quoted from post at 15:07:16 09/10/21)
(quoted from post at 10:45:51 09/10/21) Good morning,
I have a Ford 8N that I am trying to troubleshoot the hydraulic system. I have read a lot on this forum but can't find answers to a few problems I seem to have.

Here is what I have:
My 3-point hitch works with no attachments or with light implements like a box blade but wont pick up anything heavy like a bush hog. The leak down is pretty slow, it will hold the box blade up for a while after shutting it off.

I removed the inspection plate and did not see/hear a significant amount of oil dripping from the top lid which leads me to think the cylinder/piston are ok. I replaced the relief valve and that did not fix the problem.

Since I had the oil drained down (not empty), I watched the pump with it running and noticed oil and fine bubbles coming out of the top of the valve caps in the chamber. Would this be the cause for my loss of pressure and cause the lift not to pick up heavy implements? I am stuck and don't know if I should just drop the pump and rebuild or keep troubleshooting. Thanks for any help.

There should be nothing coming from the caps and yes that is likely your problem.

TOH
o gaskets at valve tops/plugs, so what is to keep it from seeping a little?
 

My dad checked on his 8N and did not see any oil seeping out.

TheOldHokie, if this is the problem, do you think a pump rebuild is the solution?
 
(quoted from post at 08:27:34 09/13/21)
My dad checked on his 8N and did not see any oil seeping out.

TheOldHokie, if this is the problem, do you think a pump rebuild is the solution?

If they are leaking I would just check and fix the sealing surfaces on the top of the chambers. If you still have pressure problems after that you can re-evaluate the situation.

TOH

This post was edited by TheOldHokie on 09/13/2021 at 06:06 am.
 
(quoted from post at 10:04:00 09/13/21) Any recommendations on fixing the sealing surfaces?
hate to see you chasing something that be be insignificant, so consider the volume of your leak compared to the 2+ gallons per minute that pump is capable of producing. Does it matter?
 
(quoted from post at 08:56:10 09/13/21)
(quoted from post at 10:04:00 09/13/21) Any recommendations on fixing the sealing surfaces?
hate to see you chasing something that be be insignificant, so consider the volume of your leak compared to the 2+ gallons per minute that pump is capable of producing. Does it matter?

Valid point, I think my next step is going to be checking the pump pressure to determine if it is within correct range.
 
(quoted from post at 12:44:36 09/13/21)
(quoted from post at 08:56:10 09/13/21)
(quoted from post at 10:04:00 09/13/21) Any recommendations on fixing the sealing surfaces?
hate to see you chasing something that be be insignificant, so consider the volume of your leak compared to the 2+ gallons per minute that pump is capable of producing. Does it matter?

Valid point, I think my next step is going to be checking the pump pressure to determine if it is within correct range.

If your lift lacks power you almost certainly have low hydrauluc pressure. The million dollar question is what is the source of the pressure loss. Its very difficult to isolate the N- Series pump from the rest of the lift circuit so pressure checks as a pump diagnostic are problematic. I am open to thoughts. How would you proceed Jesse?

Dan
 
(quoted from post at 19:55:07 09/13/21)
(quoted from post at 12:44:36 09/13/21)
(quoted from post at 08:56:10 09/13/21)
(quoted from post at 10:04:00 09/13/21) Any recommendations on fixing the sealing surfaces?
hate to see you chasing something that be be insignificant, so consider the volume of your leak compared to the 2+ gallons per minute that pump is capable of producing. Does it matter?

Valid point, I think my next step is going to be checking the pump pressure to determine if it is within correct range.

If your lift lacks power you almost certainly have low hydrauluc pressure. The million dollar question is what is the source of the pressure loss. Its very difficult to isolate the N- Series pump from the rest of the lift circuit so pressure checks as a pump diagnostic are problematic. I am open to thoughts. How would you proceed Jesse?

Dan
would remove the right side inspection port, drain oil lever down to just covering top of control valves (for better observation of leaks around pump), chain lift arms down, connect gauge, start and select lift. Measure pressure, look carefully inside around lift cylinder, pump, over pressure valve, at lower corner just above where test port is located (inside & out) and vertical tube connecting pump to top cover for turbulence/unusual oil movement.
vJgHdLe.jpg
 

We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today.

Back
Top