656 hydro wont move

[ih656]

have a ih 656 diesel hydro that will only move in revrse in low and high gear range. but it will not go forward when you push the lever forward it just makes a loud noise on the right side of the tractor. some one told me my hydro was bad and then some told me that theres a forward and reverse relief valve and that the forawrd one could be stuck? if so how and where is it located and how much do they cost to fix?

 

[JohnG IN]

I have a 656 hydro and when my relief valve failed it would not move in either direction and it did not make any noise, but that is not always the failure mode.
If it is working normal in reverse and does not slip if you apply the brakes in reverse, the hydro is likely OK. One relief valve is behind the angled plate on the left side. You must drain the hydro section by removing the drain plug in the hydro section, about 5 gal.
The other relief valve is behind the hydraulic pump on the right side. The relief valves are the ones that have the ~1/4 steel pipe attached to them. Look at the parts diagram on the Case IH parts web sight, 656 powertrain center section
You can check the valves by placing the hex head on a flat surface, pour paint thinner in the end with the ball and it should not leak out.
Do not overtighten them on install I think the correct torque is 23 ft. lb. but do your own research.

 

[ih656]

Ok just put it in reverse with brakes on and the
hydro is not slipping it didn't skip a beat. So the next
step is to locate new relief valves and new fluid and
filters

 

[pete 23]

Like other poster said, if one relief valve is stuck open, either fwd or reverse, the tractor will NOT move in either direction. I would strongly recommend doing some checking before tearing anything apart. The best and easiest test is to cap off both those fittings that the two steel lines come up to control valve. Doing that will show you if your problem is inside or outside. You could have a bad capsule in the drive control valve causing your problem, in fact, that is the most likely cause. Not the only cause but most likely. You could have a stuck shuttle valve or broken snap ring off the end of it. Or, broken check valve also. The shuttle valve can be checked from outside under large pipe plug near top center of hydrostatic housing. Check valves are inside. When capping off those fittings, you will not have any foot n inch valve control, only the speed ratio lever so take care. Have room. Easy test though.

 

[Allan in NE]

Common ailment. Forward check valve.

Allan

 

[southtexas]

I have a an IH hydro service manual and in the trouble shooting section it says the likely cause is the forward check valve, which is located behind the L shaped plate on the right side of the transmision. The check valve is no bigger than a half a roll of quarters and costs over $250, but it is very easy to change out. Relief valves cost the same or more I have heard.

Before I would buy any valves i would do what pete says and cap the two small lines that come out of the transmission going up to the drive control lever. That will tell you if the problem is in the transmision or external. Foot and inch pedal will not work when you cap the lines so be careful.

There are some very experienced guys on this site that can help you, I am just passing on what i have learned from them while working on my own 656 hydro.