656 hydraulic problems???

[JerryF]

656 Gear drive. Back pump works fine, but front pump bare puts out enough pressure to lift loader if engine at WOT. Power steering works, but doesn't quite seem 100%. I changed pressure relief valve and font pump from a donor tractor, that I know were good. After changing pump and relief valve, pressure is around 800psi at the couplers.
The inside control valve sticks (almost locks at open or close) and just doesn't seem right, but the second is smooth. Pressure out of each is around 800.
Could the problem be the contol valve or is it more likely the stering proportioning valve or a suction tube inside? I am fustrated, thanks for your help.

 

[skyharborcowboy]

Might get more hits in the International Forum.

Joe

PS. I had a lot of problems with my Power Steering that was caused by sucking air into the system (pump cavitation). Over fill by five gallons and see if that fixes your problem like it did mine.

 

[Allan in NE]

Hey Jerry,

I don't have a clue as to what is going on with your tractor. Just some things to "think about" tho.

Some of the early 656s had a little 7 gallon front pump. Syphon off 3 1/2 gallons for the power steering as a given and you can see where I'm going with this. There is no loader in the world that will work on that amount of residual oil.

Also, IH hydraulic pumps are built by putting a couple of steel gears into a aluminum body and that body naturally will wear away/wobble out over time.

Point being, "A known good pump" is kind of a "iffy" thing at best. 800 lbs is about what a '39 H would develop on it's best day.

Now add to the mix the fact that the first 656s were never, ever designed to run a loader off the tractor's hydraulic system. They just weren't; not enough built-in capacity.

Back to your tractor: I think as you do. Something wrong with that front oil/front pump and it's related system.

After assuring myself that the oil level and filter were okay, I'd go back to square one and buckle in a 17gpm front pump on that guy. Can't express strongly enough how much difference it will make.

Hope ya get 'er figured out,

Allan

 

[JerryF]

The initial and replacement pumps are both 17 gal pumps. Loader always worked fine until the last year seemed to get weaker, then all of a sudden on a cold December day I went to lift the loader and heard a "thunk" sound. Had thought that it may be an o-ring or even pump crack, so that is why I replaced it. In the meantime I also replaced a slightly leaking line from power steering down to body. This may have caused some air. Will try tonight to overfill with 5 gallons.

 

[Allan in NE]

I hear that "Thunk" sound every moring when I'm feeding cattle.

My noise is coming from a wobbled pin hole in the left front axle tube. Always happens when changing directions and that tube will "slip/turn" a tiny bit.

Allan

 

[JerryF]

I put in an extra 5 gallons in and now have no more pressure, but the loader will go up slowly at WOT. I unhooked the loader lines and hooked up a log splitter with the pressure gauge in line. No problems with it. Must be air in cylinders I thought. Hooked loader back up and went up and down about 10 time to try to bleed system, but not getting any better. Any tips for getting the air out?

 

[skyharborcowboy]

If you have no pressure you have to have a stuck (open) pressure relief valve somewhere. That is just about the only thing I can think of that can cause that sort of thing. Possibly the addition of the extra fluid alleviated any cavitation you may have been having and allowed the pressure to spike to normal levels further sticking an already stuck open relief valve. Off of the top of my head that is the only thing that makes sense.

Joe

 

[skyharborcowboy]

Sorry, I think I misread what you were saying. Can you try to disconnect the lines and pre-charge the cylinders to purge the air out of the system sort of like pre-filling an oil filter before installing it on to your engine?

Joe

 

[Anonymous-0]

The 656 has a rubber hose on the suction line.Drain the oil out & see if the hose has split.This is a common problem.I f the hose is OK check for a cracked hyd. manifold above the differential.Hope this helps.

 

[JerryF]

Not sure, but I think it may just be air in the system now. Tilt is working fine on the loader but, lift is slow and weak. Swapped hoses from on the two auxillaries and tilt still good and lift still poor.
Tried bleeding starting with steering ack and forth. Then running each cylinder through and holding for a minute to push out all air. All seemed to bleed out except for the loader"s lift cylinders. Do not see any leaks anywhere. Any ideas?

thanks!

 

[TX656]

(quoted from post at 18:31:46 02/15/08) The 656 has a rubber hose on the suction line.Drain the oil out & see if the hose has split.This is a common problem.I f the hose is OK check for a cracked hyd. manifold above the differential.Hope this helps.

LBSMJS, what panel or part of the tractor do I remove to check the hose (and manifold). I'm also still fighting a loader problem on a non-hydro 656.

Also, guys how do I check the pressure at the rear remote? I have the IT shop manual but didn't find that test in there. (I think I have an IH service manual at work but not at home for reference right now.)

Several posters have mentioned replacing the relief valve in other posts. Which relief valve? The one that the IT manual says is part of the power steering checks? The recommendation was to upgrade to the relief valve that was standard on the 686 if memory serves.

Thank you everyone for your help.