DongFeng Hydraulic Issues

[Lionel72]

I have a ZB25 that has been working fine but 2 days ago I was slashing my property and went to lift the slasher. The slasher would not rise. When I looked into it further I noticed the 4 in 1 bucket also would not work but this was actually raised. I drove it back to my garage and could not get anything hydraulic except the steering to work. One thing I did notice was there was a very minor hydraulic leak coming from under the control valve bank for the 4 in 1. After leaving the tractor overnight I returned to check it to find it still the same. When I started the tractor. I noticed the steering section of the pump was cool but the 4 in 1 part of the pump was very hot to touch after only 4 minutes of running. The hosing appears to flex when controls are moved but nothing else moves. Any ideas

 

[olPete]

G'day, to me it sounds like the relief valve could be stuck open.. maybe. We had a dirty big MF8470 (290hp+) that used to have exactly those symptoms. No hydraulic function at all apart from steering. I had a bit of a tantrum on the brake pedals while I was phoning the technician and away everything went again for about 100 hours. Worst thing was it was a vario/hydro so it wouldnt even disengage the park brake mechanism.
So the short story is I got really good at spiking the hydraulic circuit by rapidly jumping on the brake pedals (hard!)
We eventually realised it was the big McHale fusion baler wrapper had something awry in its valve bank and was putting alloy filings through the system, and being light they stayed in suspension in the hot oil. Filter on the pickup to the pump sorted that. Is your tractor new? Or older?
Cheers
Pete

 

[Lionel72]

It's about 7 years old. I bought it 3 moths ago and has not missed a beat till now. I suppose the other question I have is how is the slasher connected to the bucket hydraulics if they run 2 seperate controls

 

[olPete]

That possibly rules out metallic fluff in the system then. Do you know if the previous owner used hydraulic powered implements or the like on it? I dont think your leak/seepage will be causing it to not operate at all, unless its got absolutely no oil in it! Sounds like it's all going round and round but not building any pressure, which points to either a pump failure or the relief valve is stuck open and it's losing all its pressure that way.
There are some real experts on here that will have way more idea than I, but theyll be asleep just now. I'll do a bit of searching the web and see what I can find out about your machines system. Might not be heaps of info but the Internet is a big place! Have you heard the relief valve squeal at all since you've owned it? When you shut the bucket it should have made it squawk at some stage.

 

[olPete]

Have read up the instruction manual for your machine.. one other possibility is the filter needs replaced, or the pump's done a seal. Havent located the safety valve yet but I'll keep reading.

 

[olPete]

It's about 7 years old. I bought it 3 moths ago and has not missed a beat till now. I suppose the other question I have is how is the slasher connected to the bucket hydraulics if they run 2 seperate controls

Haveyou not had the slasher on it for long? Is it run from the hydraulics for the loader?

 

[Lionel72]

The slasher was on it when I bought it. The slasher is operated by a lever to the right of the seat and appears to go straight onto the gearbox area. No noises heard at all it has been an awesome little tractor. I did search the net that's how I found this forum but open to ideas. Unfortunately I bought it from a deceased estate so I have no history. The hydraulic oil level is good and it looks very clean. I will try to get hold of a filter morrow and try that first. Here's hoping

 

[rd_macgregor]

This is a long shot, but...my Kioti has a flow rate adjuster which I once accidentally screwed in (it is on the floor, under the front of the seat, by my foot). This messed up the behaviour of my hydraulics; I thought something serious had gone wrong, but the valve was just retarding fluid flow.

 

[olPete]

This is a long shot, but...my Kioti has a flow rate adjuster which I once accidentally screwed in (it is on the floor, under the front of the seat, by my foot). This messed up the behaviour of my hydraulics; I thought something serious had gone wrong, but the valve was just retarding fluid flow.

So does the dongfeng in question I'm pretty sure. It has a little knob by the 3ph control but from what I took from the manual, its just for the rear lift.

 

[olPete]

The slasher was on it when I bought it. The slasher is operated by a lever to the right of the seat and appears to go straight onto the gearbox area. No noises heard at all it has been an awesome little tractor. I did search the net that's how I found this forum but open to ideas. Unfortunately I bought it from a deceased estate so I have no history. The hydraulic oil level is good and it looks very clean. I will try to get hold of a filter morrow and try that first. Here's hoping

Ah thats good, my reason for asking was that maybe it was unsuited to your tractor or connected it a way that had toasted your pump seal. I'm still leaning towards it being the safety valve..
As to whats next:
Id try to locate where the relief valve is and maybe remove it and see if you can tell if its allowing all the oil to dump, or perhaps a call to Midway to see if they have any advice? Failing that id get a hydraulic pressure guage and see what pressure the pump is putting out. It could be starving and thats what the problem is, maybe oil foaming but then you ahould have operation on startup.