***"My power steering suddenly quit working"***
And what are the symptoms?
Did the steering wheel lock up where you can't turn it?
Or.......does the steering wheel just spin without the steering cylinder moving?
Can you jack up the front axle so that neither tire is resting on the ground?
If so, see if the steering will operate like that.
Try that with the engine running and with the engine not running.
This type of steering is known as "Full Hydraulic Power Steering" or FHPS. (meaning that there is no mechanical steering linkage between the steering wheel and the steering axle)
FHPS systems are required to feature a redundant back up means for operating steering in case of pump or engine failure (or a loss of supply pressure to steering valve).
The steering valve has the capability to become a "gerotor" hydraulic pump in the absence of hydraulic pressure being fed to the valve from the hydraulic system pump.
In your case, there are 2 possible scenarios (based on what you stated so far).
(1) Cylinder piston ring has suffered a catastrophic failure, causing hydraulic oil to simply bypass from one side of the piston to the other without moving the piston.
(2) Possible failure of the steering valve, or in the mechanical joint of the steering wheel shaft to the steering valve.
Most applications using FHPS have a splined male to female joint at the juncture of steering wheel shaft to steering valve.
Some applications (where the distance from steering wheel to valve is pretty short) have a rather longish shaft coming out of the steering valve and the steering wheel itself is splined to match that shaft.
So, let's have some more specific symptoms and see where we need to go with further testing.

Thank you Mownie for the quick reply....you are right I was not very specific concerning the symptoms! The tractor seemed to lose the "Power" in the power steering...the wheels will still turn, but it is like manual steering(hard to turn). I shut the tractor off and parked it in the garage and when I went back to try it again, the steering seemed fine, but quickly went away and back to the difficult operation. Could this be as simple as being low on fluid? Where do I check the hydraulic fluid? Or could the fluid be "leaking by" I dont have any fluid that has leaked out on my garage floor. Thank you for your help!

This actually sounds (now) like it is experiencing a loss of supply pressure from the hydraulic system.
I'm leaning toward the hydraulic pump being worn, possibly aggravated by hydraulic oil that has been in service too long, and has lost both viscosity and anti-foaming additives.
It sounds like the cylinder and the valve are working correctly.
The fact that it steers, but with greater effort.....is exactly how FHPS systems act when the hydraulic supply pressure drops and causes the steering valve to assume the role of "pump and valve". And since you are providing the power to operate the redundant pump, you will feel it in your arms and shoulders.
If the cylinder was bypassing oil due to the piston seal having crumbled, your symptoms would be " man, you turn and turn and turn and it don't feel like it's steering at all, not hard to turn the steering wheel but it just don't seem to be doing anything."
Another symptom of the piston seal failure would be the inability to have any "feel" of what your steering was doing, and as a result you would end up constantly steering and correcting back and forth, fighting a machine that wants to dart left and right all the time instead of tracking straight with a good solid feel.
At this time you best get a competent local technician or a hydraulic repair shop to run some pressure tests on the hydraulic supply feed to the steering valve.
It sounds like the FHPS system is resorting to its manual mode upon the loss of supply pressure, as it designed to do.

thank you, sounds like this is definitely something out of my league! Would I notice this in any of the other systems on the tractor? Is the mower deck also operated by the same hydraulics? The deck seems to raise and lower just fine.

Without a service manual description showing the specific configuration Deere uses on the 318, I don't know if it is a "shared pump" system, (using flow divider valving) or if there are multiple pump sections in a common housing using the same oil and reservoirs.
Typically, if a shared pump system is used, the power steering portion of the system will have "first priority" meaning it is fed first in the hierarchy of valves........steering system is first in line to get oil from pump, then any other functions such as deck lift or hitch lift are fed.
If the power steering system is fed from an independent pump, it is possible to lose hydraulic flow from that pump without any effect on other hydraulic functions fed from a different (and also independent) pump. From your description of how the power steering fades without noticeable change in deck lift speed, it seems like the steering system may have its own pump, separated from other hydraulic circuits.
When I say "independent pump", I don't mean that you will find 2 (or more) hydraulic pumps mounted at different places on the tractor.
Most often, hydraulic system designers will use a single pump drive to spin the pumps. The pumps themselves are connected together so that it appears to be a single pump.
In this fashion, all the individual pumps draw from a common reservoir, but have separate outputs to operate different functions.
So, if Deere uses an independent pump for the steering, it can go completely south while the other stuff continues to work OK.
But if it is a shared system, I would expect pump fade to affect other functions too.
Hydraulic system evaluation requires high pressure oil gauges, adapter fittings to tap the gauges into the plumbing, and the know how to do the tests safely.
Personal injury from a rupturing hose, or even a loose fitting...............can be extremely serious.

41flathead - hmmmm. Wonder if that's a Chevy or Ford?

Anyway, I have a JD 322 myself. Your 318 and my 322 have essentially the same hydro/differential/steering system.

To check your hydro oil: look at the rear of your tractor. There should be a sight glass on the right rear of your tractor. The hydro fluid should be in the center of that glass.

Next thing: How long or how many hours has it been since you changed your hydro fluid and transmission filter? If you can't remember, go to your JD dealer and get the proper hydro filter. Whilst you're at it, get the JD hydro fluid. You can use Type "F" automatic transmission fluid if necessary, but you're much better off using the JD stuff.

The maintenance book says about 4.6 qts for the refill. So get two gallons of JD fluid, and that way you're covered.

Purge the system by hitting your up and down hydro levers, then once you get close, put the tractor in forward, followed by reverse, and so on, and so on until it functions as normal. Make sure you stop every now and then to refill the hydro, but don't over fill.

Oh, draining the hydro usually takes a 7/16" 8 point socket. I had to use a 3/8" drive socket with a 1/2" adapter then that was attached to a 1/2" breaker bar. Usually that plug is in there very tight, so be prepared.

Try to not round off the pipe plug or you'll be very sorry on that account. Pipe plug is located just to the right side of the differential on the bottom.

Once you get started draining the fluid, jack the front end up slightly to get the flow going. It will take a good while to drain all the fluid, so don't get hasty.

You pour hydro fluid into the oil fill cap on the left side of the tractor beside the left pedestal under the hood. It is a flip type cap.

Yes, your deck is working off the same hydraulic system. In fact, you have hydro ports on the front of the tractor that can be used for the 4 way snow scrape blade, or for a snow blower. IIRC, the outermost hydro lever controls the right side ports, and also the deck lifting mechanism. The inner hydro lever controls the left side hydro ports.

If this doesn't help your steering, you could try to bleed the power steering. This means cracking the fittings near the power steering cylinder or the valve. You're trying to get any air out of there if you can.

If this fails, it could very well be the valve or the cylinder.

Hope this helps.

Thanks Windcatcher!
Actually though....it is a Dodge! 1941 Business coupe that my Grandparents gave me. 6 Cyl flathead!
Anyway.....thank you for the info, how often should the hydro fluid be changed? I purchased this tractor about 2 years ago, and use it for mowing and other summer chores. No plowing or snow or anything (dont have those attachments...YET) Is it possible the fluid is just causing this problem? Loss of viscosity or dirty or something? I will change the fluid and see if that helps...I did check the fluid level with the tractor off and it was in the middle of the glass. I am assuming this glass is just for checking the level...it does not circulate through there correct? I had seen a post somewhere talking about the fluid "pumping" back to the top through the hose....and I did not think that was the purpose of this. Thanks again!

41flathead: A Dodge? Wish I'd had a Dodge the night I hit a tree because someone had their bright lights in my eyes when I was pulling out of a drive way one night many years ago.

Left quite a dent in the front fender of my '62 Ford Fairlane.

Take care of that automobile. It'll be worth a fortune one day.

Sorry to be late in responding. Some of this information is on the technical CD, and other parts are in the owner's manual. Though I think JD has some good equipment, I think their technical information for their tractors lacks greatly. Or, it could be written better. How's that?

Anyway, at 200 hours, you're supposed to change the engine oil and filter, and also the transmission oil and filter.

This takes into account that you have done your 50 hour break in oil and transmission fluid change from when the tractor is new. ;)

I stumbled into getting my JD 322 early January of this year. Wasn't even looking for one, and it just popped up on the local Craig's list. Still have some repainting issues to deal with and more mechanical stuff, but it is coming along nicely.

Hope this information helps. These guys (and gals too) here know their stuff in their respective areas.

Oh, BTW. There's a nasty rumor about a certain character called "Rusty" being able to play a rousing rendition of "Orange Blossom Special" on a banjo. I still want to hear him play myself. :D

Cheers!

Oh, about the fill tube with the sight glass: I'm really not sure if it circulates or not. Though I've had my tractor up and running several times, I've never seen the fluid circulate. I have seen the fluid go down due to working the hydraulics and moving the tractor, but I just drained and refilled my system too. I think I still have some air in my system for it to do that.

The number three cylinder is not firing all the time, it just suddenly starts to run on all three cylinders then it goes back to running on two cylinders. It seems to run on two cylinders more than anything. I have checked the resistance of the trigger coils, the resistance of the (3) coils at the transistor module connectors.

Has anyone ever used a 4 pin GM HEI control Module to replace just one of the transistor circuits in the (3)transistor control module used in the JD322?