Jubilee 3 pt lifting problem

Jay in WA

Member
The system seems to loose it prime. I've replaced the O rings on the manifold tubes and it still doesn't lift properly. It won't lift until the tractor runs for a few minutes and the pump growls when I raise the 3pt. It only lifts in the last 2 inches or so of moving the lift handle. Is there something internal to the hyd tank that's leaking and causing air to get into the system? It has the vane pump and it has the 2 gallons fluid in the hyd. reservoir.
 
Could have a number of things wrong. Cam follower pin bad can cause that from what I understand as will fluid that is to thick due to temps or incorrect fluid or a seal between the rear end or trans being bad and mixing the thick oil with the thin oil
 
There is a seal between the drive gear and the pump that could be leaking air causing it to loose prime. It is common for the seal to wear a groove in the shaft as well so that would need repair as well as replacing the seal. As for the lifting only in the top 2 inches of travel, you should check the selector lever to make sure that is set for position control and not set to the draft control position.

Mark
 
It could be a number of things. When you say "It won't lift until the tractor runs for a few minutes" it sounds like a "Loss of Prime" issue. When you say "It only lifts in the last 2 inches or so of moving the lift handle" it sound like the cam follower pin is worn or the the linkage is out of adjustment.

Do you have the early square vane pump or the later round piston pump? If you have the later pump, the seal and shaft are replaceable and there is a good test to confirm a suction side leak (ie wobble shaft seal).
 
Guess you missed it he said he has the vane pump which can be a problem in them self's
 
Yep Old, I missed that. These old eyes aren't what they once were.

Jay. With a vane pump its harder to diagnose a suction side air leak. The only way I know is to use a rubber tipped air gun down the dip stick hole and use some low pressure air to force some oil up to the pump. If you lift improves, great. But if it goes back to the same old problem, after sitting overnight, you have a suction side leak.

If that is the case you have a problem, Parts are no longer available for the vane pumps. Two options 1) buy a used vane pump and cross your fingers, or 2) buy a newer piston pump and swap it. Again cross your fingers.

The new piston pumps are rebuild-able, so that route works, but the pumps are expensive. There are usually several listed on Ebay at any given time.
 
I have a used piston pump for the NAA and up to the 6X tractors. I have the manifold too but it of the later than NAA models and won't work on the NAA.

What manifold will work with the NAA and piston pump????

Zane
 
That is why I have glasses made just for sitting here in front of the computer. LOL Yep had my eyes checked and was told my old glasses where fine for reading but in front of the computer I needed a special pair
 
open the 'flow control' knob on the vane pump all the way
check the o-rings on the tubes front and rear again
check the tubes carefully for any pinholes, rust thru
bleed air by loosening the plug on the accessory plate under the seat
take out the test port plug (by the right floorboard), and plumb a
hose from there to the fill port. start the tractor and check flow and look for air bubbles

sometimes, the vane pumps are just worn out.
replacing it with a piston pump is then the way to go.
direct swap, but you will need
piston pump tubes for the NAA, which are getting very tough to find.
(your existing vane pump tubes won't work)
also, you will probably have to modify the oil pressure line
fitting on the side of the block, as the piston pump will hit
it when installing
 
I'm not a Jube/NAA guy, Buy I would think the hundred series manifold would fit the Jube/NAA 4 speed tranny and piston pump. The engine and 4 speed transmissions are the same on NAA's and 640.
 
The NAA is very different as it has tubes that run back to the hydraulic section externally instead of internal tubes through the transmission like the 600.

Mark
 
Thanks everyone for the help with this. I did the compressed air test to the hyd dipstick tube and it lifted immediately. So it appears it's loosing prime. I got the O rings from a local Hyd shop and he inspected the tubes and said they were OK. I will do the test of hooking up a tube and looking for flow volume next. I have not opened up the pump to look at it. It works good enough now for snow plowing so I probably won't dig much into it till spring or it quits completely.
 

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