John Deere 2640 loss all hydronic

Alarocque

New User
My father was using tractor this fall when all at once loss all hydraulic
function, no three pt, steering and pto. I have it for about two seconds
when I first start up the it’s gone. I’m thinking it’s one of the steel lines
in transmission. I pulled the shift cover off and hooked up two clear
hoses on the two lines that come up. I started the tractor up and had
flow on the bigger line and nothing on the smaller one which I’m
thinking goes the the pto brake. Is that where the problem could be?.
Before some one says filter it got changed last year with new fluids
and I did pull the long screen out and it was clean. Any help would be
appreciated thanks
 
You need a Deere service manual and a set of gauges. First confirm the trans pump is charging the front pump and then check front pump pressure and flow. It could be a stroke control valve or something else in the front pump. The service book gives all the oil flow direction and what and where to check. Tom
 

Welcome to YT

Yes hyd failure could be a failed pto clutch &/or pto brake seal

Check frt hyd pump coupler to be sure hyd pump shaft is turning when engine crankshaft is turning.
Does tractor have frt end loader installed? If so what type valve controls fel(scv or ind)?
If tractor has options of hyd pto or hi-lo check hyd's with the afore mentioned controls in both positions.
With 3 pt in raised position, engine operating, look inside open hyd filler hole behind seat for moving oil which would indicate leaking seals on 3 pt control valves.
Remove hyd filter cover with clean, empty 5 gal bucket underneath, start & operate engine for 15 seconds & measure amount of oil in bucket. There should be 1.25 gallons in 15 seconds.
Disconnect & cap line on RH side that supplies power steering control valve. Operate engine to determine if internal leaking PS valve is causing hyd problem.
 
If you have oil coming up in one of the large pipes indicates transmission pump is pumping. For testing, temporarily jump the two large pipes together with a jumper hose and use hose clamps to secure. This should allow all hydraulic functions to return confirming there is a leak in the transmission circuits. Using a rubber blow gun apply air pressure to each of the four small pipes / tubes if one open whistles inside of transmission, that tube / circuit is most likely the leak. Good Luck, DW
 
So I did do the jumper on the metal pipes. Tractor does not have hi/ low just pto brake. So there are only two small pipes showing and when tractor was running there was no oil flow between them making me think it has to do with the pto clutch/ brake. I have the tractor split now so will the air test still work? Or just start pulling the gear off to look at pto clutch?
 

My tractor with the independent PTO . The problem was two leaking Orings under the hydraulic engagement lever .
Sounds like the problems are deeper . There is a relief valve and a divert valve that affect/control oil flow . Weird stuff like oil filter Orings have jammed them .
 

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