JD 4640 hydraulics laboring engine

Andyauctioneer · Mar 28, 2020

We have a JD 4640 that keeps laboring the engine when the SCV s are in the neutral position. If you put the handle up to the stop it stops laboring. I tried adding on a third remote and we thought that plate was causing the issues but that s not the case. Changed scv s and that didn t help either. Pulled the needle valves out and they re functioning like they re supposed to. Not sure what we re missing.

Bob · Mar 28, 2020

Starting with the tractor "cool", monitor all high pressure hydraulic components for temperature rise by touch, or, better yet with a digital "heat gun", the exact component or area that has a high pressure leak will heat up quicker than the surrounding parts/iron.

That being said, the problem pretty much has to be in the unit who's lever you are twiddling with.

NOT sure what you mean by "changed "SCV's", did you swap the valve bodies around or replace the apparently offending one with a spare?

NOT sure what you mean by "Pulled the needle valves out and they re functioning like they re supposed to."???

If you've had valve parts out of the SCV it needs to be set up with a "jig" and a dial indicator (although some "old pros" claim they can do that by feel).

Post back with more clear details, please!

Andyauctioneer · Mar 28, 2020

We replaced the scv with a spare and it still did the same thing to rule out there being a problem with the scv itself. Also put the single remote plate back on and it s still acting up. Wanted to make sure it wasn t a faulty third remote plate.

The needle valves I was referring to are located inside the plate where the scv bolts to. Used for the 3 pt arms.

Both remotes act the same when we move the levers. Put a hose into the remote to complete the circuit and moved the lever. When pushed forward against the stop it stops the laboring. Does the same when pulled back. When in the neutral position is when it labors the tractor.

matthies · Mar 28, 2020

Sounds like you don't have the levers adjusted right. The tractor should labor when the lever is pulled back against the stop and also labor when pushed ahead to the stop(the forward stop is a moveable piece to put the lever in float). To me it sounds like you are moving the lever to the float position(all the way ahead with the moveable piece raised up), it labors in the lowering position, and is then in the neutral position went it is not laboring again. Did you happen to just get this tractor or have had it for a while?

JD Seller · Mar 29, 2020

You need to get some gauges on the tractor to see what is going on. It sounds like the stroke control valve in the main pump, is not destroking the pump when there is zero flow. All your doing with the loop hose is just allowing the hydraulic oil to not deadhead.

JD 4640 hydraulics laboring engine

Andyauctioneer

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Bob

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Andyauctioneer

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matthies

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JD Seller

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