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2000 JD 4400 and 430 loader problem

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Horizon
Join Date: Feb 2004
Posts: 2 Otoe
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2004-02-03          75846

Have a problem I have been trying to diagnose for a while. Loader drifts down while in use. When trying to raise loader slowly, it will drop. Replaced spool valve last spring and the problem was still there until I used it some then problem magically went away. Used loader hard this past fall and problem is back. Swapped lift arm and bucket hoses to spool valve with no effect. Dis-connected lift arm hoses with loader raised, loader dropped only small amount. Wondering about the main pressure control valve. Any thoughts?



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2000 JD 4400 and 430 loader problem

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Chief
Join Date: Jul 2003
Posts: 4297 Southwest MiddleTennessee
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2004-02-03          75848

What is your hyd. pump pressure? Could be the pump is allowing some leakage? Just a thought to consider. Is the speed of the hydraulics any slower that when it was working properly? ....

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2000 JD 4400 and 430 loader problem

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deeremd
Join Date: Jul 2003
Posts: 18 maryland
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2004-02-03          75851

I don't know about the 430 loader; however, the 419 loader on my 790 will also drift down over time. According to my JD dealer, this drifting is perfectly normal with the types of valves that JD is now using. Anyone else experienced this?
....

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2000 JD 4400 and 430 loader problem

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ncrunch32
Join Date: Dec 2003
Posts: 762 Kingston, NY
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2004-02-03          75854

Sure - my 430 loader on JD4310 will slowly drop when tractor is shut off. It will drop maybe 5 inches in 15 minutes. My 47 BH will also drop when tractor is running and I have to keep it pinned up when not actively using it. But this drop is to be expected according to operator manual (although it is annoying).

I have never noticed the FEL dropping while tractor is running - I am usually adjusting the bucket position often enough that this would not be noticeable. Nor has the FEL ever dropped when I raise it slowly - at least not that I noticed.
....

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2000 JD 4400 and 430 loader problem

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harvey
Join Date: Sep 2000
Posts: 1550 Moravia, NY
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2004-02-03          75864

Was the spool valve new or rebuilt? When was the oil changed last? What type of oil in it? Oil strainer? Oil filter?

Sounds like the valve leaking or bypassing. So it could be a bad "O" ring or 2. So why did it happen the 2nd time? That was the question about hyd oil and new or used or rebuild valve. ....

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2000 JD 4400 and 430 loader problem

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Horizon
Join Date: Feb 2004
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2004-02-03          75878

New spool valve. New oil (JD recommended). New filter. Having dis-assembled the old spool valve, there are no replaceable internal oil rings (nothing inside the spool valve can be repaired). Have not yet checked the oil pressure. Have also attempted to bleed any air out of the loader by cracking fittings - didn't notice any. As new spool was over $300.00 (self installed) I'm trying to eliminate all other possibilities. It seems odd to me that both the lift arm and roll back spools would both be bad. ....

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2000 JD 4400 and 430 loader problem

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TomG
Join Date: Feb 2002
Posts: 5406 Upper Ottawa Valley
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2004-02-03          75890

I think JD publishes standards for acceptable leak down rates. Some people consider the acceptable rates unacceptable so there's a good chance the leak down is within standards. A dealer should be able to say what the standard rate is.

Some pure theory here about drop when feathering the valve. Such a thing could happen if the spools weren't quite coordinated. For example, the work ports may open slightly before the return line is completely blocked. If the valve has anti-cavitation valves then feathering the valve could allow oil to pass from the lower side before pressure in the lift side builds. There likely are other possibilities but with any of them I wouldn't have a clue why the problem would be present in a rebuilt valve, then go away and reappear again. Little use to this except armchair theorizing I guess. ....

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2000 JD 4400 and 430 loader problem

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BrentB
Join Date: Jul 2003
Posts: 21 Illinois
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2004-02-03          75898

I had the same symptoms with my 420 loader. I'm pretty certain you have blown one of the lift cylinder seals. The clue is when you try to lift slowly that the loader drops. This is because the oil you are metering in to lift is leaking past the piston seal and back to return. when you lift fast you put more oil in than can leak past and the loader still goes up.

IT cost about $75 for the dealer to fix the cylinder a year ago. Search this site for leaking lift cylinders to learn how to test which one it is, or post here and I'll add the instructions.
Regards,
Brent ....

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2000 JD 4400 and 430 loader problem

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TomG
Join Date: Feb 2002
Posts: 5406 Upper Ottawa Valley
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2004-02-04          75919

A leaking cylinder seal sure might do it. It'd be a simpler explanation then my theorizing, which might have gotten a bit confused from thinking that both the lift and bucket circuits are involved. I re-read the posts and think I was also recalling another thread where the person had disconnected the work port lines, which greatly reduced the leak-down. That's not a bad test to separate valve from cylinder leaks. A better test is locking down the bucket so it can't lift, disconnecting the lower line and trying to lift it. If the cylinders are leaking, oil should come out the lower line. I've never done the test but if I had to I have a spare quick-connect fitting so I could open the line without removing the fitting. ....

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2000 JD 4400 and 430 loader problem

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larry1957
Join Date: Jun 2019
Posts: 4 Monkand ON
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2019-06-16          198553

I also have drop in my 430 loader, just bought the tractor so need to study it a bit but I agree with the cylinder seal leakage. If I lift slowly it drops but if I lift quickly it lifts and when I let go it drops 4 to 6 inches then settles but will slowly drop over time while moving. I will try the test of cracking the return line and see if it leaks when holding the bucket down. That makes sense. ....

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2000 JD 4400 and 430 loader problem

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larry1957
Join Date: Jun 2019
Posts: 4 Monkand ON
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2019-06-21          198568

I'd like to follow up on the loader drop, it was exactly as TomG suggested, the cylinder seals were leaking. The left cylinder seals had been changed in the past as the dust seal was fairly new but the right cylinder was really difficult to disassemble due to corrosion. Some moisture had penetrated the first o'ring on the end cap. I suspect it was original from 1999. If you are not a good mechanic I'd suggest paying a service tech to do the job. The 3/8" hole they supply to turn the cap is not sufficient if its corroded. I machined a 1/2" /18 threaded bar and used the oil port to turn the end cap off. Thanks TomG. ....

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2000 JD 4400 and 430 loader problem

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larry1957
Join Date: Jun 2019
Posts: 4 Monkand ON
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2019-06-21          198569

BTW, just hit me, the moisture could enter through the lock ring opening, DUH ! ....

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