Ford 801 3pt issue - not smooth - stuttering on the way up

Removed lift cover cleaned and installed all new seals and o-rings.
Now after all that. 3pt works fine and seems to have good power. But whenever it is lifting it is not smooth. shakes while lifting. Stuttering on the way up.
Don't see anything about that in the service manual.
Not like it doesn't work. It could be used, but I would like to cure this if I can.



Any ideas?
Or experience in this symptom?

Thanks
 
Valves in pump sticking/non functional.

Did you use gasket goop anywhere in the system or allow gasket material or other debris to fall into the hydraulic sump?

Dean
 

Thanks
Thats what makes sense to me too.
No did not use any adhesive or goop on any surfaces.
There was a lot of rust that had fallen into the oil and laying in the butom of the of the sump. Cleaned it all out - flushed it - new oil.

removed everything I could and cleaned - including valves
But the Back pressure valve was really stuck - #20 and 21 in the service manual ....I got the Check valve # 17 18 in front of it out ok.
Didn't want to brake something - so I left the Back pressure valve as is. Partly thinking I could get it out without removing the cover if I had to look into it further.

Other Questionable item. The relief valve in the buttom....Did not remove this. But, not sure if this could cause this?

Also removed the control valve and the unloading valve in the lift cylinder.

Let me know your thoughts.
Thanks
 
Any helpful hints on getting the back pressure valve out?....and the valve seat?...

Is there a way to force air behind it to get it to move?...

Seems like the likely culprit since it is stuck. Just would make sense.

Happy to hear anyone elses thoughts.
Thanks
 
It's not the relief valve.

Removing the pump so as to remove the cylinder head to inspect/clean the valves is not difficult.

If you do so, do yourself a favor and order the correct, square-cut O rings for the aluminum hydraulic manifold. Order a head gasket and 2 or 3 paper gaskets/shims for the pump at the same time.

Upon reassembly, verify that all O-rings are properly positioned before torqueing the nuts to proper specs. Do not overtighten. I install grade 8 washers on the manifold studs to better distribute the forces.

Dean
 
Let's make sure we have all the air out of the system. Remove the 3/8 plug on the head of the pump and verify the system is fully bled of air.
 
First thing to do is follow Wayne's advice. Air in system will make the lift chatter and studder while raising. With the engine at idle speed loosen the 3/8" pipe plug on the top front of the hydraulic pump. When it pumps a steady stream of oil with no popping sounds then, all the air should be out of the system. The lift should raise smoothly then. If not then you can go on the other things.
 

Opened the plug on the pump while running at idle late yesterday,
and let a generous amount of oil out, for a few seconds. May have been some air at first.
May do that one more time today to make sure.
 

Opened the plug on the pump again this morning while running, lots of good oil coming out. Closed it again while it was running.
Still the same.
Did not seem to help.
 
It seams to be time to pull the pump and check up on check valves, springs and etc by removing the six bolts that hold the pump head. The gasket will probably stick holding the head in place but once the head is pried loose , spring pressure will push the head up
 

Got the back pressure valve out. Used a 3/8 20 fine thread bolt and various washers and things to pull it our by the internal threads.
Yes, I said internal threads. This valve has threads inside that can be used to extract it out.
I'm going to give it all a good cleaning and new o-ring and put it back together. See if that cures it.

There was also another valve in the lift piston I had removes some days ago with a fine thread bolt. That one was a 1/2 20 fine thread.

I wish I was better at posting pics on here. I have numerous pics I could forward along.
Never had much success getting them to work.

I'll post back on how it turns out.
 

You talking about the main pump running off the flywheel?

I would be surprised the pump could cause this symptom.

But I am asking for ideas.

Interesting theory.
 
(quoted from post at 11:13:00 06/12/19) It seams to be time to pull the pump and check up on check valves, springs and etc by removing the six bolts that hold the pump head. The gasket will probably stick holding the head in place but once the head is pried loose , spring pressure will push the head up

I'll look at my service manual about this and give it some thought.
 
(quoted from post at 15:13:03 06/12/19)
You talking about the main pump running off the flywheel?

I would be surprised the pump could cause this symptom.

But I am asking for ideas.

Interesting theory.
would be a lot more surprised if the cause was the back pressure valve !
P.S. pump is driven off camshaft, not flywheel.
 

Removed the back pressure valve cleaned and reinstalled it.
Still the same.

Oh well. One more thing off the list of possibilities.

At least I know it is clean and functioning.
 
If a cylinder in the pump were malfunctioning, it looks as though you would perhaps notice a 7 times per second pulsation at idle speed, instead of 42 per second if all is well. Could you or I detect that difference? I don't know. Maybe, since we can see the 120 pulse per second of fluorescent lamps.
 
JMOR,
I am not sure about the math on the pulsations (I don't think you are wrong, I just don't know the gear sizes etc.), I do know that my 64 4000 had a shutter or vibration during it's lifting cycle.
I took the pump down and found 2 of the check ball springs broken. I reasoned that I was getting 4 pistons pushing and 2 pistons feeding back pressure in opposition.
Mine was bad enough that the balls on the lift arms would rattle.
For good measure, I did a complete rebuild with bearings and seals.
The system works great now. (been 10 years or so)
So I am with Dean. Tear into the pump!
HTH
Keith
 
(quoted from post at 16:05:09 06/12/19) If a cylinder in the pump were malfunctioning, it looks as though you would perhaps notice a 7 times per second pulsation at idle speed, instead of 42 per second if all is well. Could you or I detect that difference? I don't know. Maybe, since we can see the 120 pulse per second of fluorescent lamps.

Thanks
 
(quoted from post at 16:05:09 06/12/19) If a cylinder in the pump were malfunctioning, it looks as though you would perhaps notice a 7 times per second pulsation at idle speed, instead of 42 per second if all is well. Could you or I detect that difference? I don't know. Maybe, since we can see the 120 pulse per second of fluorescent lamps.

I'd rather think about the issues and determine what and why before I start the pump removal. If I understand how the pump can cause this, ok yes, then definitely move on to that.
 
(quoted from post at 20:44:43 06/12/19) JMOR,
I am not sure about the math on the pulsations (I don't think you are wrong, I just don't know the gear sizes etc.), I do know that my 64 4000 had a shutter or vibration during it's lifting cycle.
I took the pump down and found 2 of the check ball springs broken. I reasoned that I was getting 4 pistons pushing and 2 pistons feeding back pressure in opposition.
Mine was bad enough that the balls on the lift arms would rattle.
For good measure, I did a complete rebuild with bearings and seals.
The system works great now. (been 10 years or so)
So I am with Dean. Tear into the pump!
HTH
Keith

Ok, Thanks Keith. That makes sense. I have not had one of these pumps apart before, but from what you said, I can see how it can cause my symptom.

Sorry guys, don't mean to minimize the encouragement that it is the pump, but I need to understand why. How can it produce this symptom. Now it is clearing up for me.

Thanks for all the posts.

So, next is parts.
I see a repair kit on the parts Yesterdays Tractor $36.36
Anyone have recommendations if this should suffice?

Or like Keith mentioned, should there be more replaced....

Thanks
 
(quoted from post at 09:47:36 06/13/19)
(quoted from post at 20:44:43 06/12/19) JMOR,
I am not sure about the math on the pulsations (I don't think you are wrong, I just don't know the gear sizes etc.), I do know that my 64 4000 had a shutter or vibration during it's lifting cycle.
I took the pump down and found 2 of the check ball springs broken. I reasoned that I was getting 4 pistons pushing and 2 pistons feeding back pressure in opposition.
Mine was bad enough that the balls on the lift arms would rattle.
For good measure, I did a complete rebuild with bearings and seals.
The system works great now. (been 10 years or so)
So I am with Dean. Tear into the pump!
HTH
Keith

Ok, Thanks Keith. That makes sense. I have not had one of these pumps apart before, but from what you said, I can see how it can cause my symptom.

Sorry guys, don't mean to minimize the encouragement that it is the pump, but I need to understand why. How can it produce this symptom. Now it is clearing up for me.

Thanks for all the posts.

So, next is parts.
I see a repair kit on the parts Yesterdays Tractor $36.36
Anyone have recommendations if this should suffice?

Or like Keith mentioned, should there be more replaced....

Thanks
ou are going to need to disassemble and inspect BEFORE you can determine needed parts.
 
(quoted from post at 13:26:19 06/21/19)
I did pull the pump off.
And am looking into that.
Ill post back what I find out from that.
ook for broken valve springs and broken springs at pistons.
 

Rebuilt the pump. Put it back on.
Lots of air I had to get out of the system. I actually removed the plug on the top of the pump. Pulled the wire off the coil. And just kept cranking the starter until all the air bubbles were out. ( Had an oil pan under to catch oil ) Don't be afraid to keep doing this as long as there are large bubbles of air coming out.
Works great now.

Thanks for all the help guys.
 
(quoted from post at 18:20:49 06/23/19)
May I ask, what did you find wrong, if anything?

Pat
oesn't it just chap you when they never follow up with findings!? :x
 

There were numerous broken springs and pieces of the springs in the pump.
These are the small springs that keep pressure on the steel balls in the pump.
 
(quoted from post at 14:24:10 08/20/19)
There were numerous broken springs and pieces of the springs in the pump.
These are the small springs that keep pressure on the steel balls in the pump.
big thank you! :)
 

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