Yanmar vio35-3 swing and blade weak

[farmnfly]

I have a vio35-5 and have noticed the swing and blade functions have lost hydraulic power. I have seen several post regarding the same issue but have not seen any replies that address or correct the issue. It looks like they run from the same pump section. Is there a relief setting on the pump that can be adjusted? is it pump wear? all other functions work fine. The machine has about 5000 hrs on it always well maintained. Looking for a hydraulic schematic or any help, thanks in advance

 

[uffex]

Good day farmnfly
I believe your trouble is as you describe coming from the same source I suggest you begin by checking the pressure on that pump just "T" into the line out if there is no test point - check with engine at idle and full speed. If you like to get back with that information try to help some more.
Kind regards
Uffex

 

[uffex]

Opps omitted the shcematic

 

[farmnfly]

I had some time to look into it some more today. I put a gauge on pump #3 (middle pump) and held the blade fully raised, the pressure only went to 1000psi. Next I disconnected the output hose and put a manual flow control valve in its place, I started the machine and shut down the flow (I had a hose off the flow control going into a pail) as far as i could and the pressure still only went to 1000psi. I think this pump section is a gear type pump and it has plenty of flow but when i restricted the flow the pressure should have spiked to around 3000psi. when I have more time I will pull this pump section apart, I'm guessing there is a problem with the internal relief valve or there may be an internal crack somewhere inside the pump section. I will post the progress

 

[uffex]

Good day
Depending how many hours the pump has made it is far more likely that the gear wheels are passing fluid - according to the schematic the only relief taking care of the pressure is on the valve chest - normally gear pumps do not exceed the 2700 p.s.i. limit the higher the pressure the shorter the life, the relief valve could be at fault but if the issue was progressive with use it is more likely that of the pump.
Rebuilding a gear pump is tricky without tolerances and test bench often these are scrapped as the cost of rebuilding exceeds new costs.
I hope the information is helpful.
Kind regards
Uffex

 

[farmnfly]

Thanks for the info and hydraulic schematics, I haven't read one much since college in the 80s. I'm hoping that when I take it apart it is just light scoring on the sides and cover (i have had good luck in the past with gear pumps, using a surface grinder, taking off equal amounts off each component). Beyond that do you know what brand pump it is and where parts my be available. Again thanks for the help!

 

[uffex]

Good day
Sorry we do not have that information however if you can take a photo of the pump lable we can take a look to see if we can locate the unit maker.
Attached is what information we have.
Kind regards
Uffex

 

[uffex]

The pump unit is similar to that installed on the Takeuchi (Guess they are using the same Uchda )

 

[HydraulicGuy]

farmnfly the picture uffex sent looks like it’s a piston pump? Is that what you’re seeing? Did you disconnect and put your flow meter in right at the outlet of the pump or after the directional control valve? If you hooked it directly to the outlet of the piston pump you normally won’t get the correct ready depending on the pumps control sensing circuit.

 

[farmnfly]

Here is an update on the Yanmar, I removed the gear pump and took it apart. The bushings in the housing were worn and allowed the gear pump to wear on the housing, basically everything was worn and not repairable. The pump from Yanmar was around $1,100 I took a chance and bought a china pump off ebay for about $600. The pump fit fine but I had to purchase some additional fittings to connect the hoses, the china pump had metric threads at the pump so I had to purchase metric fittings and metric to NPT adapter. With these fittings I was able to use all the original hoses. So far it works fine, I did find the same pump on Alibaba for $180 but I don't have an account set up and and the shipping is expensive. The pump from ebay had free shipping and it got here in 5 days from china

 

[uffex]

Good day FF
Great you got it sorted for reference often there are many outfits who make gear pumps its worth digging out the spec for yours and shopping around often you can find such pumps making a small change to the connectors can save a lot of money.
Kind regards
Uffex