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The PTO runs through the tractor below the hydraulic tank and would not contribute to hydraulic temps.
When there is no hydraulics in use the pump is working against the pressure relief valve. The internal friction caused by squeezing and moving the fluid is what causes it’s temperature to rise. IN the winter as the fluid heats up I cycle all the hydraulics to get the warm fluid to warm up the rest of the system. At rest the fluid just circulates through the tank and back to the pump. It takes a long time to warm up the cast iron tank and 3 point cylinder.
It is possible that whatever is causing the fluid to flow through the steering gear when it is not supposed to is temperature related. As the gear warms up a passageway may be opening up or a seal may start leaking.
A higher viscosity fluid may help with the issue but is likely to only mask the problem and not really fix it.
It will be interesting to see what temps you observe at startup and after an hour or so of operation.
As a reference point my loader (ZL20) says it will lift 875 pounds to full height. It should raise in 6.5 seconds and lower in 5.0 seconds. It is not specified but I would assume that the times are for a no load condition and at operating temps and probably at full or nearly full throttle. It might be interesting for you to check the times both cold and hot to see how it relates.
The hydraulic tank on the 284 is the small tank just under the seat. The 3 point lift piston is inside that tank. It sits above the rear differential and does not have a common sump with the transmission/drive system. The tranny/diff uses 80W-90 and the hydraulics uses hydraulic fluid. The tank was sized to run the 3 point and the steering. Adding a loader to it just about maxes it out capacity wise because it only holds about 2.5 Gal. Running the PTO will have no effect on the hydraulics.
If the fluid level gets too low it might cause overheating. My experience with the 284 is it is impossible to get the fluid to overheat. In fact, I have the opposite problem, especially in the winter at sub-zero temps. The cast iron in the tank, all the hoses and lines and loader cylinders act like big radiators and dissipate heat so fast that the fluid remains stiff even when working the tractor hard.
Think of it this way. The only energy being put into the hydraulic fluid is done by the pump and any friction it may encounter in the hoses/lines. Everything else extracts energy from the fluid, either by doing work or by radiating heat. That poor little pump has a hard time imparting that much energy into the system. Somewhere there is a formula for calculating all this. Basically you figure out the heat input, minus the work output and what is left over is residual heat that must be extracted by the tank/lines/cylinders. If they can’t keep up the remaining heat (usually expressed in Watts or BTU’s) determines the size of cooler you need. There are more details than just the basics listed here.
If your hydraulics are overheating, you could feel it by touching the tank after an hour or so of operation.
If you aren’t getting proper pressure your loader would be week and your steering would be stiff, not moving around on it’s own.
Back to your steering issue: If you use the loader and lift the front wheels off of the ground with the engine running they should not turn on their own. If they do there is something wrong. I never did buy that it was the cylinder leaking and replacing the cylinder and still having the problem proves that out.
Fluid temperature (viscosity) might effect how much of the problem is displayed but I doubt it is the problem in itself.
Personally, I like to take things apart to see how they work. I don’t know how the steering gear works at controlling the fluid in and out of the cylinder. I would likely resign myself to the fact that I need a new gear. I might look for a used one to try if that is even possible. Some of the dealers may have a scraped tractor that they are parting out or someone else may know of a source of used parts. In any case, I would take is as an opportunity to take the existing one apart to see what makes it tick. I might get lucky and see something obvious like a blown seal or gasket or severe wear. There probably aren’t parts available and I suspect that once I got it apart there would be no hope of putting it back together in working condition. But I would take a look knowing that I am probably going to have to buy a new one.
That reminds me I have a refigerator compressor that quit after 33 years. Made a terrible noise before it died. I’m going to cut it open just to see what went wrong. I suspect either a bearing or a motor mount broke.
I don’t know exactly what is wrong with your steering, but all the testing and replaced parts points to the steering gear as the culprit.
Well that is depressing. It does confirm your observation of fluid flowing out of the gear without any steering input as being the problem. It also confirms that a cylinder (leaking or not) would not cause the symptoms you are having.
Looking at my own 284 more closely I was wrong about the role of the priority valve. It does not give priority to the steering over the loader. The loader is in the circuit before the p-valve. What the p-valve does it give priority to the steering over the 3 point. The p-valve plumbing does not change with or without a loader.
Since the p-valve sends fluid to either the steering gear or the 3-point I don’t see how it could possibly effect the steering gear output.
Unfortunately that leaves only one part left, the steering gear itself.
The old one is a little blurry. Does it use the same type of seal as the new one?
Please post a picture of the fittings as they used a couple of different styles on the loaders.
Measure the inside of the threads on the cylinders and the outside of the threads on the fittings. Post the measurements and we can figure out what you have. Then we can look for suitable adapters.
The 20mm x1.5 jam nut fit perfectly on the steel line, which as an o-ring on the end of it’s face. So, now I need to find a 20mm cap that has a flat face on the inside, or I need to find a full size 20mm nut that I can weld a plug with a flat face inside it.
That is for a DIN fitting and probably won’t work on a face seal connector. The only place I have DIN fittings on my 284 are on the Z-20 loader. The tractor and backhoe all seem to be either O-Ring face seal or BOSS seal (sealing washer with straight threads). DIN is a different animal completely.
Maybe you could use a metal “slug” and another o-ring. By slug I mean a metal disk like a knockout from an electrical box or maybe even a coin.
Put the slug between the two o-rings and re-assemble the joint. That would provide a makeshift plug so that you could do the testing on the cylinder. Just don’t forget to take it out before starting the engine!
You should be able to find the appropriate cap online somewhere. Your idea of welding flat metal to a nut with an o-ring for a seal sounds like a good solution too.
Another option is to use a 9022FC adapter to convert it to a 1/2″ JIC fitting. JIC caps are easy to find. Take a look at adaptall.com for all kinds of goodies along this line.
Neither the tractor nor engine parts books for my Jinma 284 show the pump to engine connection details. It is my understanding that the pump has a tang that protrudes from the pump. This tang engages a slot in the drive gear of the engine. I have never had my pump off so I am not sure what it looks like on the inside.
Do you know what engine you have? That might help to find a parts diagram of how things are supposed to be.
Short of that, could you post a picture or two of the pump and pump mounting point taken with the pump removed so we can see what is inside the housing?
Try an equipment dealer. Caterpillar has quite an assortment of things if not in stock at least available. Bobcat or Kubota dealers might have metric caps and plugs too.
Double click the image in previous post to open up the whole chart.
There are two styles of o-ring seals for straight thread connections. One is o-ring face where the seal is on the end of the tube and the other is sometimes called a BOSS fitting where the seal is either an o-ring held captive in a washer that sits at the base of the threads. Sometimes these washers have the rubber seal molded onto the washer so they are one piece.
If you can get a plug or cap to seal you can fill one side of the cylinder and plug the port. Then apply pressure on the cylinder rod and check for leakage at the open port. Keep in mind that a cylinder that leaks in one part of the travel may seal in other places.
You are on the right path to figuring out the problem before spraying parts (and $$) in hopes of guessing right.
