Hydraulic bug hunt

[valley]

Greetings, This problem is on a Foton 254 with a ZL-20 FEL. FEL when tractor is first started won't move, when warmer slow, and when nice and warm works good.
I have a couple of thoughts first: On the FEL's valve lower left is an item sticking down. [This is the best shot of it I have now. ] Is that a pressure regulator of some kind? Click to make larger.

 

[valley]

Here is where I'm going! when I turn the wheels to full lock {when cold] the loader begins to move. Full lock must create hydraulic back pressure. Somewhere the oil moving at low or no pressure until the oil is warm. Since the power steering works at all times it has to be in the loader valve, the divider valve or the 3 point! That's what I come up with! What do you think? Richard

 

[Philscbx]

A couple of things need to be looked at.
Take a sample of the oil, and see what it's pour point is like cold.
Sounds like the base weight is too heavy.

Next check the hydraulic filters.

The pressure relief valve maybe damaged from wear.
Check the main, and your FEL control valve.
Pull it out and inspect the ball or poppet and seat.
They can be rebuilt easily.
I've seen the poppet and seat worn out with cut polished grooves like a laser from fine debris.

I'd start with those 2 main items first.

 

[greg_g]

I believe you may be trying to point out a pressure relief valve. But you've been fighting this issue through several threads on more than one forum. Why don't you summarize here what you've done so far? That should help avoid a bunch of redundant questions.

I've seen folks suggest to you before that this is symptomatic of flow restriction, typically caused by thick hydraulic fluid. It's winter. It takes time for the oil to warm up and thin out, to the point where it will pass freely through the restriction points (screens/filters, valves, controllers).

Since the FT254 is of separate-sump design, I believe you were advised to drain/flush/refill with AW32 hydraulic fluid - to clean or replace the suction filter in the sump - then to inspect/clean the valves on the pressure side (priority/loader/lift) if flow is still restricted. How much of that have you accomplished?

//greg//

 

[Diamondpilot]

You cleaned the Priority Valve. You need to change the fluid. This is a common issue with Chinese tractors. You need to clean the system with a flush and service with AW32 non foaming hydro fluid like Greg has suggested.

Chris

 

[RonMar]

Yep, it does sound like too thick of an oil in the hydraulic system. The works better as it warms description is a dead give away. My 254 came with what looked like 30 weight oil in the hydraulic sump. Maybe it was UTF. It had the same oil in the gearbox. Well it is too thin for gearbox oil and too thick for hydraulic fluid. If yours is the same, you need to change all the gearbox and hydraulic oils. My hydraulics work fine in all the temps I encounter where I live with AW32 in the system.

 

[valley]

OK! I've drained the sump,and cleaned the bottom, but have not flushed the system. I extended the suction pickup deeper into the sump. I refilled with Anti wear ISO 32. I now have a suction screen I plan to put in, there was not one and the pickup was only 1 1/2" into the sump. This time I will flush the system. Yes! I did clean up the divider valve.
Then:I went on to do all the things not related to hydraulics you do when you get a tractor new from China,fluids and adjustments, I think they were never done.
Now: I think getting the hydraulics in working well,before converting and changing anything, is in order. I just heard some good information.
I started this thread on the hydraulics because there are other things that can be talked about and information searched without clouding hydraulic repair here. Richard

 

[Frankm]

Hello . My 20Hp Nortrak done the same thing from new , in the summer it works fine , in the winter it is just like yours , i have done all the things there telling you to do , and it is still the same , if you fiend out whats wrong with it please let me know at corvette@velocity.net , Thanks !

 

[valley]

Frank, You got it! If I find the bug I'll stick a pin in it and send it to you. Richard

 

[valley]

One by one as time and weather permit

1. I will, when the weather clears, flush the system and install a Jinma suction strainer and fill with fresh hydraulic 32.
2. Open the FEL Valve and see what it has to say.
3. ?