I have a 76 4430 s/n 061134 that I bought last fall. I didn't get to run it much last year but now trying to get some field work done the tractor is loosing hyd functions when it gets up to operating temps. I have a jd service manual on its way. Been doing some research on here to try and provide as much info as possible. Tractor has about 35hrs on hyd filter, and I just cleaned the suction screen. I did not find anything abnormal on the screen, just some black crud, no big pieces or metal fragments.
First off the line feeding the priority valve blew out of the adapter two weeks ago, didn't think much of it replaced the o-ring and back-up ring, yesterday after I took my first set of pressure readings while it was cold, took it out and run it on the disk for a while to get up to operating temp, came back to the shop and that line was spraying a nice stream where I just replaced the o-ring and backup ring.
Anyway the standby pressure was 2250 cold.
Checked pressure at clutch port, 155psi idle, 175psi at pto speed.
Clutch depressed was 0psi.
Pto clutch port, 0psi with pto out and 165psi pto engaged
Brake port, 160 idle, with pto in 0psi.
Cooler port, idle 5psi and 105psi. at 2000 rpm
I did leave the gauge hooked up in the clutch port while I was running the tractor and it stayed at 165psi at anything over 1500 rpm and at idle would drop to 125psi.
I didn't recheck the rest due to oil leak.
Thinking the charge pump is getting weak, really appreciate the professionals opinion. I hope I have enough info to go on.
Thanks,
Derek
First off the line feeding the priority valve blew out of the adapter two weeks ago, didn't think much of it replaced the o-ring and back-up ring, yesterday after I took my first set of pressure readings while it was cold, took it out and run it on the disk for a while to get up to operating temp, came back to the shop and that line was spraying a nice stream where I just replaced the o-ring and backup ring.
Anyway the standby pressure was 2250 cold.
Checked pressure at clutch port, 155psi idle, 175psi at pto speed.
Clutch depressed was 0psi.
Pto clutch port, 0psi with pto out and 165psi pto engaged
Brake port, 160 idle, with pto in 0psi.
Cooler port, idle 5psi and 105psi. at 2000 rpm
I did leave the gauge hooked up in the clutch port while I was running the tractor and it stayed at 165psi at anything over 1500 rpm and at idle would drop to 125psi.
I didn't recheck the rest due to oil leak.
Thinking the charge pump is getting weak, really appreciate the professionals opinion. I hope I have enough info to go on.
Thanks,
Derek