656 hyds

Hyds.surge when in use at high rpm but works fine at lower rpm. Pumps have been replaced twice. Hyd.fluid is 5 gal.over full. Tipping side to side,nose up-down makes no difference. Cannt put a handle on this problem. Any suggestions? Havent tryed changing relief valve yet. Thanks

Has a new hyd.filter installed.

I'll take a stab at this. Do you think it is the pumps surging or is it a bypass kicking in and out at high rpm? Pump surging to me would make some kind of cavitation sounds at the pumps while a psi relief valve tripping would be more of distinct off sound when it opens in the area of the relief valve.

Is it doing this while operating any particular thing such as the steering, loader, remotes, etc or is it doing this while everything is static?

I wouldn't think the pumps are surging but you could tell by pulling a line loose somewhere and stick it in the hole for the fill plug and watch the flow.

A pressure guage would be the probably way to trouble shoot it.

Your main psi relief valve is back there on the block by the draft control housing. My 2606 also has one under the housing cover in the front right corner by the other block.

Pull the seat and the cover (don't mess up the gasket underneath and fire it up and see if there is any surging there. While open you can clean out the sludge that collects in the bottom of the rockshaft housing.

I suppose before doing that, there are other bypasses. The power steering bypasses to the line going into the front oil cooler and then back to draft control/rockshaft housing.

Before pulling the seat, crack some lines around the steering and different places to see if you can isolate the problem. Pull that relief valve out from the block to see if that is the problem.

Finally, or better yet first off, maybe get a mechanics stethoscope or a makeshift piece of pipe, tube, or rod and go around to the various parts with the end to your ear to check the relief valves and give them a listen.

Sounds like a weak psi relief valve but hate to see you buy a new one (they are expensive) and that not fix it. May be some kind of crud blocking something or I found that the one under the seat in the housing on my 2606 had a piece of metal under the ball holding it open. (it looked like a broken piece of the spring but when putting it in the vise to open the ball, it fell back into the valve but it still works and hasn't caused a problem yet.)

Post back and let us know what you find out.