International 404 not pumping after filter change

j in Pa

The repair manual says that anytime the system has been opened, you have to fill the reservoir and cycle the power steering several times to bleed the air out of the system. There's more:

It seems that the pump puts oil to a flow control valve that directs the oil to the power steering unit until the needs of the power steering unit are met. That means that the power steering unit has the higher priority for oil and the valve gives the oil to the power steering unit before any goes to the hydraulic system.

If there is trash in the system, it may be blocking the valve. You may be able to clear it out.

If the flow valve has problems, the flow control relief valve are not operating correctly, you'll need to get it looked at by someone who has pressure testing equipment and can rebuild or repair the valves.

Or if you are handy, get a repair book and have at it. If the parts are damaged, you will need a rebuild kit.

Hope it's just air in the lines. The other way looks like a rainy afternoon of work.

UFO Man

Let's assume that the filter replacement went as it should. There seems to be a very exact procedure for that.

The troubleshooting guide says as follows:

Response time too slow, could be caused by:
1. Unloading valve piston sticking,
2. Unloading valve orifice plugged (partially)

Next, your now problem

Hitch will not raise, could be caused by:
1. Unloading valve orifice plugged.
2. Unloading valve piston sticking.
3. Flow control valve spring broken, piston sticking or check ball stuck in orifice. 4. Unloading valve ball no seating.
5. Main relief valve spring broken or valve is leaking.
6. Cylinder safety (cushion) valve faulty.
7. Auxiliary valve cover "O" ring damaged.
8. Linkage diconnected from control lever or valve.

The book also says that the unit should be cycled at least 10 to 12 times to purge air, but I don't think that air is the problem here.

It may be that something that was part of the original problem, like a partial plug of the unloading valve is now a plugged unloading valve.

Try this first, remove the filter plug from the transmission top cover at the back of the axle housing. Fill rear center frame to level plug opening with fluid, Start the engine and with the filter plug out, cycle the lift system and any remote cylinders several times, 10-12, then place the levers in the forward position. Cycle the power steering from one extreme position to the other, then straight ahead. Recheck the fluid level. If there is air, this should take it out. If it isn't air, start with the unloading valve and the flow control valve, they seem to be good candidates for being plugged or otherwise not functioning.

Good Luck and keep us posted.