Hydraulic pump whine after valve installation?

[Gypsyman]

Well, I finally found enough free time to install the hydraulic control valve on my 186D for the front mount snowblower and all functions work perfect including the PB for the 3-point.

I have noticed a strange side effect after the install though. When the engine is throttled up the hydraulic pump now whines like it's under a load. If you run one of the cylinders all the way out and hold the valve over the relief the noise instantly disappears. It also goes away when lifting the 3 point.

All lines are 3/8" and the hydraulic pump was silent prior to the valve install. So, here's my question. Does the 186D need 1/2" feed and return lines to allow proper circulation when not under a load?

Richard

[dex3361]

Is the valve you installed an open center or a closed center?

[Gypsyman]

I installed a Prinve LVT with the optional PBY plug installed. Attached is the Prince sheet for the valve I used. I'm using the "power beyond option C" on the Prince sheet.

[oldnslo]

Can you describe how you plumbed this LVT valve into your existing system? Is your 186D a open center or closed center system from the factory?

Closed center version allows for this valve to be installed in parallel with your existing 3PH. I.e. the pressure line teed to feed both valves.

Open center version: The valves are plumbed in series. I.e. Pressure would be to your LVT valve. Then the PBY port on the LVT valve would supply pressure to the 3PH. Tank port on the LVT would go to tank.

[Gypsyman]

Corrected my earlier post to reflect my current installation.

The valves are plumbed in series. Pressure to the LVT valve. Then the PBY port on the LVT valve to the 3PH. Tank port on the LVT to the tank. This is exactly as the Yanmar manual states.

Here's something I found this morning. The oil is heavily aerated. Even though I know better I went ahead and changed the hydraulic filter with no change to the problem. My next step is to pull the plug from the Yanmar divider block and see if thing return to normal. This would effectively eliminat the LVT valve from the system.

I'm stumped on this one since all system function correctly.

[oldnslo]

I recently installed a LVT1BG5AB7 valve on my Branson 2400H to replace the stock FEL control. This valve had a #4 SAE plug that I removed to install a gauge in the pressure port. Plug was located on the side of the valve direcly in-line with the pressure port. These valves come from the factory with the relief set at 2000 PSI unless specified differently. I would suggest installing a gauge in your pressure line to what is happening during operation. For reference: On mine at around 4 GPM flow I see 200 - 300 PSI with all of the valves in neutral.

NOTE: I did notice that it takes roughly 800 PSI to raise my FEL when MT and you do get more fluid flowing noises than the stock valve but 100% improvement in FEL control.

Heavily aerated flow can be caused by a relief dumping to tank.

[Gypsyman]

Problem solved.

If it looks like cavitation and sounds like cavitation then it's cavitation.

One of these day I'll learn to listen to that little voice that says check the obvious and never trust used parts, no matter how clean they appear.

I flushed the hydraulic cylinders on the used Yanmar snowblower (all looked clean) and cleaned the hydraulic strainer on the 186D last week so I assumed that everything was good to go. Since the pump sounded like it was cavitating I decided to pull the strainer again just for general purpose. It was totally plugged with garbage. Even though I flushed out of the lift and chute rotation cylinders there must have been some gunk built up in them from the long term storage outside at the previous owners house. Putting hydraulic pressure to them once again dislodged it and sent it into the system.

Cleaned the strainer and all is well. Snow is coming tonight so I'll get a couple of hours of run time on it and service the hydraulic system again just to make sure I got it all.

[murphy1244]

Good Job!!

[oldnslo]

One of my favaorite sayings is "Stubborness will overcome common sense" All to often this keeps me from looking for the obvious.

Good job and hope it all works well.

[Gypsyman]

Well...

Forget everything after hello. I thought that cleaning the strainer had fixed the problem but it's still there, just at a higher RPM range.

Just to recap. With 3/8" lines the pump whined all the time at anything above 1000 RPM. I upped the line size on the inlet, tank return, and PBY circuit to 1/2" which cured the problem as long as the control valve is in the neutral position. Th 3-point no functions smooth and quiet, just as it did before the control valve install. As long as the RPM is low the functions controlled by the valve are smooth and quiet. As the rpm is increased the cavitation/restriction noise and jerky hydraulic action get progressively worse. It actually sounds like the hydraulic pump is chattering over the relief.

My last option is to rip out all of the new 3/8" plumbing and go to 1/2" throughout. Very irritating since the install was very clean and for once the hydraulic shop hit the alignment on every hose perfectly.

Can anyone confirm the GPM of the hydraulic pump on the 186D? Jamiesons told me that it was about a 6 GPM pump and recommended the Prince LVT valve. What concerns me is that the LVT series valve has #6 ORB ports for the work functions which limits the maximun ID of the fittings that can be used for stepping up to 1/2" lines.