NAA weak hydraulic pump?

Tuna IL

Member
3pt lift is slow, hydraulic pump will lose prime overnight. With lift arms chained down , gauge at the test port, only showing 1100psi. Which would be about half of what it should be from searching the post on here. Just wanted someone to confirm my diagnosis. Should add it is a piston pump, not vain. I have ordered a shop manual just not here yet.

thanks
charlie
 
Yep first thing to do is pull the dip stick inspection plate and have a look see. As for loosing prime that maybe worse problems like a pin hole in a line that runs threw the transmission
 
actually not so bad on the naa.. the naa uses external lines that run under the tractor.. not them bajeebers that run thru the tranny.
 
Just checked again. The lift piston is moving in and out as it should with no leaks that I can see at all and no steams up top, while gauge showed 1100 psi. Weak pump?
 
My first thought was that you had a major leak in the lift piston. Since you have checked that and it appears OK, I would check the pump further

Is the lift jerky or smooth? If its jerky, I would try bleeding the pump by the pipe plug on the top - front of the pump. If you are up for a task, pump in a clear plastic hose and run it to the fill hole under the seat. Start the tractor. If you see bubbles running though the plastic tube, you have a suction side air leak. If you just see oil, I'm thinking you might have a few broken or worn check valve springs inside the pump.

If it were mine, I'd bleed that pump and see if it improves things. Just break the pump bleed plug loose (just a bit) and run the tractor at slow idle. Loosen the pipe plug just enough for oil to flow. You may see bubbles. Once its only oil, tighten the plug and check the lift. Be careful, if the plug comes out with the tractor running, you'll be moping up oil all over the barn.
 
The lift is smooth, but very slow. If it sits more than a day I have to bleed the air from the pump at the pipe plug on front of pump. When bleeding the pump it takes 20-30 sec to go from bubbles to oil to get the air out.
 
A slow or weak piston pump and no air might be the check valves or check springs are wore out or gone, in the pump.
 
Tuna, I think you are looking at a pump rebuild. Loosing the prime overnight is a classic sign of a failed pump shaft seal. Over the years, the seal wears a groove in the wobble shaft that requires replacing both. In order to do that you will have to replace both bearing.

I also think you will find that you have check valve problems on several cylinders. Replacing the balls and springs is a fairly easy fix.

If you are up to a full pump rebuild, post back and we can help. Its a little more involved than normal wrenching.
 
Thanks, I will go for the full pump rebuild, It will be a month or two as I drive OTR. Until then I keep reading on here.

thanks
charlie
 
I had a piston pump. Did a rebuild, purchased everything. Later I discovered the seal that wears a grove can be pressed in a different location and I could haved used the old shaft.

My problem was a broken spring. It too lost prime.

George
 

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