4430 hydraulic issues

DManey

Member
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
 
When I run it for a few hours I will eventually lose the steering at idle but comes back as soon as I throttle up to 1500+ rpm. I haven't actually used the three point but lower it and raise it while hot it just chatters unless rev'ed up. Also lose hydraulic function at scv unless rev'ed up over 15-1600 rpm.
I can raise the disk idled back when I first start the tractor for the day but that doesn't last very long.

Thanks,
Derek
 
Sounds like the stroke control valve is sticking open....that would be in the front pump,, you can turn the wheels all the way to the left and reach up into the opening near the steer arm and loosen the nut that takes a 3/4" wrench, and back the screw out a a ways then back in till the outlet pressure is near 2250psi,, be careful that the steering don't drift and pinch you..
 
(quoted from post at 19:15:19 05/29/17) Sounds like the stroke control valve is sticking open....that would be in the front pump,, you can turn the wheels all the way to the left and reach up into the opening near the steer arm and loosen the nut that takes a 3/4" wrench, and back the screw out a a ways then back in till the outlet pressure is near 2250psi,, be careful that the steering don't drift and pinch you..

Ok sounds good I will try that tonight when I get home from work and report back.
Thanks,
Derek
 
Had to order the adapter fitting that holds the priority valve in. Won't be here till Thursday, I will post back with results then.
Thanks,
Derek
 
Well I tried adjusting the stroke control valve like you said tim. Still no difference. Is there something I can try next?
Thanks
Derek
 
Let me know what you find out. I've got
similar issues. My original thought was
the transmission pump. Haven't taken
time to check it. I only use my 4430
for loader work so not as much of a
problem here. Email is s'posed to be
open.
 
I just read your post, and you could have a high pressure leak that is warming up the fluid, and weakening the pressure, do you notice ether of the SCV's getting hot quicker than the should. this is one place for a high pressure internal leak,, a heat gun is helpful to find a hot spot,,taking a few readings as it all warms up can help you in the right direction. I had a 4440 in here last weak that was acting a lot like yours, and it did turn out to be a SCV heating up too soon, I resealed it and that seemed to take care of that one..
 
Well I have let it run for 20-30 minutes and nothing seems to get hot too quick. I will see if I can get ahold of a temp gun. The SCV''s do need gone through, but was hoping to wait till fall. Maybe have to get on them sooner.
Thanks
Derek
 
Hey Tim I forgot to mention that this tractor has a power beyond kit on it too. I'm not sure if they can add to the problem, I have no use for it but it was on there when I bought it.
Thanks,
Derek
 
Well finally picked up a infrared thermometer yesterday and got to diskip with the tractor for a couple hours before a low pressure hydraulic line under the hood decided to leak. But anyway the scv's were all within a few degrees of each other. #1 was 139 and #2 was 145 and #3 was 146 degrees. #3 was the SCV I was using if it makes any difference.
Thanks
Derek
 
(quoted from post at 22:52:13 06/07/17)
At those temperatures scv's aren't your tractors hyd problem. Take temp of steering & rockshaft control valves.
Forgot to add rockshaft was roughly same temp. I will check steering next. Hey on another note, does the line going to the priority valve vibrate on all these tractors? I keep having to re-torqe the bolt that holds the block that splits off and goes to the accumulator under the cab. That 3/8" bolt was broke when I bought it, put new spacer and grade 8 bolt in.
Thanks
Derek
 
I cut hay for four hours yesterday, checked the temp of the steering valve and I got temps as high as 165° at the top of the valve. lThe bottom of the valve was considerably cooler at 125°.
 

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