JAAZ
Member
Hello, I have a 1982 John Deere 670A I have run and maintained for 12+ years. The machine transmission always operated well despite the lube pressure always ran a little on the low side according to the gauge. This spring I drove it across town and lost drive in all speeds in forward and reverse. It seemed for a while the hydraulics continued to work but eventually would quit. I never lost steering. After shutting the machine off for a few minutes I could start it up and drive a few hundred feet then again quit driving. Before losing drive power, I would witness the lube gauge lose pressure then 10-20 seconds later the transmission pressure gauge would drop off prior to losing the drive.
I have changed the filters and screen in the transmission as well as checked all relief valves for broken springs and o-rings. Nothing jumped out at me. There was some evidence of clutch material but not very much. I would like to note in recent years it would slip a little under load but infrequently.
At this point I am suspecting an internal leak or possible bad transmission pump. I have read a couple others have the same symptom online however I have never read of a resolution. It seems this may have been a common problem as these machines as they age and was curious if somebody out there would know where I should tear into.
Other than constantly blowing an Oring in the left blade lift cylinder poppet valve which I have never been able to solve, this is a very tight machine that is worth fixing if possible.
Thanks for any help.
I have changed the filters and screen in the transmission as well as checked all relief valves for broken springs and o-rings. Nothing jumped out at me. There was some evidence of clutch material but not very much. I would like to note in recent years it would slip a little under load but infrequently.
At this point I am suspecting an internal leak or possible bad transmission pump. I have read a couple others have the same symptom online however I have never read of a resolution. It seems this may have been a common problem as these machines as they age and was curious if somebody out there would know where I should tear into.
Other than constantly blowing an Oring in the left blade lift cylinder poppet valve which I have never been able to solve, this is a very tight machine that is worth fixing if possible.
Thanks for any help.
