4710 Relief Valve Noise

[Anonymous Poster]

Gentlemen/Ladies:

Has anyone experienced what sounds like hydraulic relief valve noise on their 4x10 tractors? My 4710 sounds like it's running over the relief valve much of the time (often briefly, immediately after starting the engine, and then more or less constantly while operating the backhoe or parked at slow idle). The dealer claims that the sound is actually caused by air in hydraulic the system, and that the noise should eventually subside based on what they've seen on other tractors.

Also, while on the subject of hydraulics, the 460 FEL will not hold position when heavily loaded, as both bucket curl cylinders and boom lift cylinders are drifting down. Any one else experiencing this performance malady? I have 3rd SCV and power beyond hydraulics.

Thanks in advance for your responses.

- Clark J.

 

[beenthere]

I am not sure, but the noise you describe sounds familiar to what I heard when my JD 4300 was new. I thought of it (describe) as a 'singing' noise (Now that I type it that way, it doesn't seem very descriptive!).
But it does sound like a relief valve, and the sound went away after some use. Often when I would hear it, moving the 3pt a bit, or changing the rpm of the engine would cause it to stop. Also, when the oil warmed up the sound would diminish or stop. I don't hear it anymore.

I did not have a problem with the loader dropping. I am wondering what you mean by 'heavily loaded' and when the dropping occurs.

 

[rancar]

I've not experienced any of these problems on my 4710. The drifting action you describe may be normal, especially under heavy loads, as hydraulic system will lose pressure over time. That's why FEL, when raised in the air, will gently drift down until it's resting on the ground when not in operation.

 

[Rockyroad]

I don't know if this will help, but I had a similar problem on my JD750 after 15 years of use. When the 3pt hitch was fully raised, I would hear the pressure relief sound.

What it turned out to be was I has the draft link chains adjusted too tight so that the 3pt hitch could not raise all the way to to the top when the lever was set to raise it all the way to the top. In other words, the chains were restraining the draft link arms and the hydraulics were bypassing. The way I found it was that I noticed that if I lowered the 3pt lever slightly, the noise went away. I readjusted the chains and the problem went away.

 

[JATO_RaT]

Clark the typical reason for the hydraulics to drift or leak down is the control valve. On very critical situations, the control valves clearances are held to higher tolerances. I'm not familiar with the JD hydraulic relief, I'm not sure I have ever heard a hydraulic relief valve relieve itself.

 

[Anonymous Poster]

Thanks for the input. The dealer has explained that the hydraulic drift down is due to the design of the open-center hydraulic system. He maintains that the leakdown is a normal condition, and the implement drop will occur more quickly when the implements are under load.

The only time I've encountered hydraulic drift down to the extent that I'm seeing on this tractor, is on equipment that has a leak in the hydraulic system. As for the "heavy load" to which I referred in my earlier post: when the loader is near full-rated capacity (in my case, moving palletized 275 gallon water tanks or a bucket full of stone, approx. 1 ton).

Now, what has me really aggravated, is that the rod on the 48 hoe's stick cylinder bent today. This failure occurred under a moderate load, raking at a section of root leftover from a stump that I removed some time ago. This is the second stick cylinder to fail in just a few hours of use (the tractor is presently at 32 hours, and I've used the hoe for maybe 3-5 hours at best). The first cylinder had an internal problem, which resulted in a catastrophic failure of the cylinder under no load (while extending the stick), literally seizing the cylinder and scoring the chrome on the rod.

I'm none-too-impressed with the 48 backhoe at this point, and I'm unfortunately beginning to have some misgiving about my decision to purchase a JD product. I've never had a major part failure on my Kubota B-7100 in my 22 years of ownership, and 2,500 hours of use.

Any thoughts?

- Clark J.

 

[dmccarty]

Maine TreeFarmer,

Sorry it took so long to answer....

I have a 4700, 460, and 48. I don't have leak down on the FEL with
the engine running. Now if I leave the FEL bucket off the ground
eventually it will fall. The only time I have turned off the engine with
the FEL off the ground is when I was trying to use the bucket as a
work stand to maintain my chainsaw. But after a while, hours, the
bucket was on the ground. I think if I had a load in the bucket,
left it off the ground, and killed the engine then the FEL would leak
down.

I don't have relief valve noise.

I have worked the heck out of my JD 48 backhoe. I broke one bolt
that holds the pin in place which in turn keeps the dipperstick and boom
togather. And that was my fault.

I have dug up hundreds of stumps. A good dozen or two 36+ inches
in diameter. A couple of holes 6-7 feet deep. No problems other than
some leaky couplers on the PBK. Knock on wood.

I have about 330-340 hours on the tractor in about 20 months. I
would guess I have something like 100-150 hours on the JD 48.

How did the cylinder bend?

I sure would be frustrated with your problems.

Later,
Dan McCarty

 

[Anonymous Poster]

Dan:

Thanks for the reply. The dealer has determined that the cylinder failure resulted from my changing the control pattern on the hoe (reversing the stick and boom controls, as I'm used to Cat's configuration, and not particularly ambidextrious). JD has a static relief valve on the boom spool, but not the dipperstick spool. So, when I encountered enough resistance, the cylinder was the next weakest link in the system, absent a functioning relief valve on the spool.

I'm presently trying to figure out whether I can place an additional static relief valave in the system (one on the boom spool and one the stick spool), to ensure that the system is well protected from exceeding its designed pressure.

Still no word on why the tractor howls like it's tripping the relief valve on the main hydraulic system. I'm happy to hear that you've had good luck with your tractor and hoe. I'm a little disappointed the JD doesn't fit two relief valves on the hoe's control valve, as it places the stick cylinder at risk if the operator is using one control, and the system cannot relieve itself accross to the adjacent (closed) spool.

Hopefully, my problems are over. Thanks again.

Clark J.

 

[kubmech]

The drift down sounds pretty normal for your situation and I wouldn't be too concerned about it. However, wiping out two dipper cylinders sounds like a problem. I wonder if your dealer tested the secondary/overload/safety relief valve on that circuit. Assuming you have a secondary relief, which I believe you do. The secodary relief valve is set at a higher pressure than main relief. It's job is to bypass the fluid in the cylinder back to tank if an excessive external load is placed on the cylinder. When you say "raking" you mean with the backhoe hyd's and not grabbing in with the hoe and using the tractor to pull I hope?!!?

 

[kubmech]

You slipped more info in while I was typing. Now I get it. Check the spool sections for a plug where the secondary relief valve would go if the controls were set up as the factory intended. You may be able to swap the secondary reliefs to match the hose change that you did to swap the control functions. Here's what I mean: The secondaries for the boom circuit are set at different pressures than the secondaries for the dipper. You swapped the hoses to change the control pattern but you left the secondaries the same. If you swap the secondaries as you did the hoses you should eliminate the problem.