3PH . . . again

[Dadsgreenpsd]

Well, I got the hitch to lift, and changed the oil in the hydraulic system at the same time. My manual recommends 30w engine oil for everything, and I have seen several recommendations for AW hydraulic oil on the boards. Which is correct? I refilled the system with AW. The reason I ask, is that the hitch valve is very stiff/sticky now, to the point that I broke the lift lever tonight, on the first time using it. Could that be the cause? The loader seems to work properly. Help!

 

[greg_g]

That's normal after a refill like that. Depending upon how often you use the hydraulics, the jerkiness will go away quickly. Mine only lasted about 30 minutes. Come winter time, you'll be darned glad you don't have 30wt in there. Can't explain the broken lever though - coincidence?

//greg//

 

[RonMar]

It could be that a piece of crud was in the hydraulic plumbing and found it's way into the spool of the 3PH control valve. The valve shouldn't feel any different when changing fluid from 30WT to the AW. I would disassemble the 3PH spool valve and slide the spool out of the valve body to visually inspect it and the bore it slides in. These are a close tollerance fit and a small metal shaving or piece of crud could get in there and make the spool hard to slide and eventually wear a groove which will allow the valve to leak.

 

[greg_g]

</font><font color="blue" class="small">( The valve shouldn't feel any different when changing fluid from 30WT to the AW. )</font>

Yes it can Ron. The "piece of crud" scenario isn't impossible, but there is a brief period of erratic operation to expect after flushing/refilling - while the system vents air out of the circuit. Once the fluid circulates a few times around the loop, the "normal" feeling returns.

Now if one only performs a simple drain and refill, there won't be any opportunity to introduce air into the loop. I've only encountered this temporary erratic operation issue when flushing is added to the equation.

//greg//

 

[Dadsgreenpsd]

I haven't pulled the spool out again yet. I was in about a foot of muck, and needed to lift the scraper, and when I pulled the handle, it broke off in my hand! /forums/images/graemlins/shocked.gif So, off the the garage with the handle, where I welded it up. I put it back on, started the tractor, pulled the handle, ..... and There it was, in my hand again. /forums/images/graemlins/mad.gif This time, I welded it, and seamed both edges. It worked for the rest of the night, and I put it away. I was too tired, after wading back and forth through the muck. It probably wouldnt be a good idea to polish it with some 600 grit, or some steel wool, would it. Thanks again!

 

[Soundguy]

If you are refering to the spool.. I wouldn't hit it with 600.. I'd try finer..... much finer.. Many spools are metal to metal contact.. so the tolerance makes a huge difference.

Soundguy

 

[RonMar]

Greg
A change in oil may cause some erratic operation if there was air in the system, but it should not effect the ammount of force required to actuate the 3PH control lever/valve. I have experienced a gummed up spool valve before and his description sounded like that especially since the only thing done was to change the oil

 

[Dadsgreenpsd]

So, out of curiosity, what causes them to get gummed up? a piece of gasket, maybe? part of an o-ring? If I were to take it apart again, and cant find anything obvious, would some penetrating oil hurt anything? Or maybe some brake cleaner in the bore. Maybe not, with my luck, it would go downstream, and eat some of the other o-rings..... I will take it apart later on this evening, when SWMBO isn't looking. /forums/images/graemlins/wink.gif

 

[RonMar]

I have found dirt and occasionally small metal fragments in the machined grooves of loader valve spool pistons. The one that I had jam had a metal shaving that looked like the curled cutting from a drill bit. There could be gravel, hair, rat turds, dead insects or any other thing that could have found it's way into the parts before the system was assembled. In draining out the old oil and adding new, you could have possibly stirred up something in the system that was lying dormant and it found it's way to the valve. When I flushed my 284 with Kerosene, I washed a lot of small metal shavings out of the resovoir that were just lying on the bottom of the tank.

Have you checked the strainer on the hydraulic suction line for holes? This seems to be fairly common on the chinese tractors. When I first inspected mine, I found a hole and the whole assembly had worked itself loose and was about to fall off the suction pipe inside the resovoir. I replaced it with a single piece tank suction strainer and a modified suction pipe that I built.

This could also just be a coincidence and you could have a problem with the rack/pinion mechanism or the detent ball that actuates the spool piston which just chose that particular time to fail.