John Deere 410 backhoe

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I have a 1974 John Deere 410 backhoe and when warms up some the engine will lug down like it's under a load when you idle down and stall it out but when you pull on the loader lever it will come out of it until you release it then it lugs down again

 

[Keith True]

Does that machine have the radial design pump? Kind of a round pump with hex plugs around the outside of it and a T-handle on the top.That is the closed center system,and is most likely equipped with it.I have heard they could be found with an open center pump but I've never seen one.Those pumps are meant to come up to pressure and kick out of stroke.That T-handle on the top is the stroke control valve,and is meant to be screwed either in or out to relieve pressure while cranking cold or with a low battery.It sounds like your pump is not kicking out of stroke and working all the time,and only getting relief when you hit a function.

 

[elevatorman724]

On farm old farm tractors like our 4320 we had to add that destroking valve. Becausise if piece of metal gets struck in pump it won't build pressure. So it may not have the valve unless they come with it on construction equipment. Or unless someone has added it

 

[[email protected]]

Ok thanks for the reply and yes it is a closed center system. But I'm wondering if there is maybe something bypassing in the system that is keeping the pump active and not allowing it to destroke. Or are you saying that the pump needs replaced