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Discussion Starter #1
Hello,
I bought an early model JD 2640 for mowing. When I got it home and put an implement on the 3 point, the arms would not lift the load. They do go up without a load on them. The place I bought it from said to bring it back because the pump was most likely bad, and I took it back.

I sort of fell in love with the tractor. Lot's of power and the transmission had lots of speeds (hi-lo). Power steering was awesome and generally just a nice tractor. It is the 2640 with the lower, wide rear tires like a utility tractor.

Everything seemed to just work really well on the tractor.

Before I took it back, I checked the suction screen and changed the hyd filter, with no change in the lift.

I've been reading that the hi-lo might be stealing flow from the 3 point via an internal leak, and some other internal disasters that I do not want to assume. Is this a fatal issue with this tractor or a repairable issue with my limited mechanical experience?

Thank you
 

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Many hyd pumps especially closed center hyd pumps have been replaced to find out the replaced pump wasn't at FAULT. I'll give odds on a bet the hyd pump isn't bad. Is dealer that tractor came from a JD dealer? Hyd stand-by pressure needs to be checked on the 2640 which should be 2250 psi. 3 pt not raising with load could be as simple as worn/leaking rockshaft piston seal or load/depth mechanism out of adjustment.
 

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Discussion Starter #4
Questions for Tx Jim

Tx Jim,

They are not a JD dealer.

A few questions;

How would I check the Hyd stand pressure?

How involved is the rockshaft seal replacement? I've done this on a 861 ford and an oliver 550. I'm guessing the 2640 would be more involved.

How do I check the Load/depth mechanism?

Thank you.
 

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It would surprise me if a dealer other than JD had a technician that knew the correct procedure to diagnose a problem with the JD closed center hyd system. One can plug a 5000# gauge into the rear hyd breakaway couplet then move control lever the correct direction to pressurize the gauge. IMHO the rockshaft housing on a JD open station tractor such as a 2640 is easy to R&R so as to renew seals. 1st thing to do is try relocating L/D lever under seat to a different position to see if 3 pt will lift load. Another possibility is priority valve down by hyd filter is blocking flow/pressure to 3 pt hitch
 

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Another thing that can "rob" hydraulic flow is if the internal lines for the PTO clutch or brake fail. See if changing the PTO from disengaged to engaged makes a difference.
 
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