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Discussion Starter #1
Header lift and steering seem to be slow, can the pump be over -hauled or must it be replaced to get the hdy sped up. I know that 1680 hyd is not as fast as the newer models are.Any help appreciated.

thanks
 

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Has this just happen or has it gotten worse over time. If it has just happened the pump may be bad but I would check the belts and filters first. You might also check the adjustments on the flow valves located under the steps. Good luck!
 

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The hyd has been getting slower with time, I checked the inching valve last fall along with new filters. I will re-ck the inching valve along with inspecting the suction hose for a collapse. The hyd pump was going to be my last choice. Any ideas welcome.
 

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Same thing happened on my 1660. Replaced pump with new one for a 1680. Major improvement! I had to put orfices in the lines for the header lift because the header raised too fast
 

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Is this an open center 1680 with the small gear pump on the left hanging below the reservoir? If so, there is a block bolted to that bracket with a plug on top. That plug is the relief valving. It is difficult to shim, and near impossible to afford a new one. The spring weakens over time lowering the pressure.

On that same style 1680, there is a screen up by the cab next to the entry door. It is inline with the pressure line. It may be plugged.

The best investment I ever made on the hydraulics of the combine, was to put a gauge in the pressure line just off the pump. Now I have an instant diagnosis tool that will tell me with reasonable accuracy where I need to look for problems should they come up.

The gear pump, if it is the type you have, is available off the shelf at most hydraulic sales counters. There are numbers stamped into the pump that you will need. It is a tapered shaft design, but common taper.

I replaced the relief with an off the shelf unit made by Prince for about $69 or so. At that same time, since I was making a couple hoses to hook the relief valve up, I installed the gauge. Granted I need someone in the cab to hit the switches to activate circuits so I can read the gauge, but that is no problem as the truck driver is never far away.
IMO.

If you have the newer 1680, I'm not much help.
 

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We put a heavier HB header on our 1680 and we ran out of lift. As someone has mentioned, there are shims and a spring located beside the cab LHS on the valve spools. It is a pain in the butt to adjust because to do it properly you should drain the oil out of the hyd reservoir so that you don't get the perpetual oil bath. I elected to have someone hold their thumb over the hole while I screwed out the relief valve and added an additional shim in order to beef up the pressures. I believe I added an injector shim on the end of it to shorten the spring length (likely an 1/8 inch, don't be shy). It worked good and in fact helped the reel lift as well as it was tasked to the limit too with a U2 pu reel! Just be mindful of the oil bath you may get while fumbling around!!
 

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Seems to me the 1680 needs to run nearly half throttle to raise header, My pump seems to be OK. Is there a way to modify the system to make it raise at idle? I want to start to mess with the valve stack but not sure where to start.
 

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Seems to me the 1680 needs to run nearly half throttle to raise header, My pump seems to be OK. Is there a way to modify the system to make it raise at idle? I want to start to mess with the valve stack but not sure where to start.
We intentionally slowed ours down so that it wouldn't be so jumpy while running wide open. Just turn the screw under the step
 
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