Strange noise from loader valve

stevewatr · Mar 31, 2013

Hi, been working on my Oliver 770, came across an issue, thought I'd post symptoms, and get some thoughts.

tractor is fitted with a Ware loader/backhoe.

I changed the fluid in the resovoir, and the filter (return line type).

Fluid was milky, and filter was really nasty.

With fluid topped off, symptoms are as follows:

No unsual noise when running, and all spool valves in neutral.

When raising loader, a terrible noise comes from the loader valve, sort of a low pitched screech, and the loader seems slow to me. I say seems slow because this machine is new to me.

Lowering loader makes no noise, and I have enough down pressure to raise front end off the ground.

Backhoe swing cylinders, and boom work fine, and stabilizers can raise rear of tractor quickly, no strange noises, so I figure pump pressure is ok.

dipper stick cylinder is very slow, but no strange noise, so I think that's just a worn piston seal. Backhoe bucket cylinder has a bad leak, so I am not testing that for now.

Based on the above, anybody have any thoughts?

Thanks,
Steve.

Nouveau Redneck · Mar 31, 2013

If the noise is coming from the control valve, then I would suspect something in there would be the culprit.

Maybe some dirt blocking a port in the valve or an old piece of 0-ring stuck dangling and blocking things. Anything blocking the flow when you move the control valve from center could cause enough pressure build up to cause the pressure relief valve to partially open, which is probably what is actually causing the noise. I would rebuild the entire loader control valve if you're going to be opening it up anyway. I'm not familiar with that model, so you may be able to do it with the valve in place on he tractor, or you may have to remove it to work on it. If you don't have the experience or confidence to try it yourself, take the valve off of the tractor and take it to a local hydraulics shop. They should be able to do a complete rebuild on the valve for not too much money.

stevewatr · Mar 31, 2013

Yup, I think your right about the relief vavle making the noise. Judging by what kind of sludge I found in the filter housing, I would not be surprised if some hunk of crud got lodged somewhere it shouldn't be.

Thank,
Steve.

TUDOR · Mar 31, 2013

Don't overlook the possibility of a mechanical fault with the loader arms. Something may be worn or broken requiring higher pressure to be used raising them and gravity works to help with lowering.

Otherwise, I'm thinking that Nouveau Redneck is correct, especially considering the nasty fluid that you drained out.

stevewatr · Apr 20, 2013

In case anybody else views this thread looking for an answer to this type of problem, I am posting this followup. The culprit in my case was a bad suction line. The suction line hose had collapsed in a couple spots, most likely due to age, or possibly damage from one of the loader arms. Replacement was a bear, due to it's proximity to the hydraulic tank, but after replacement, the strange noise in the pump disappeared, the loader valve noise when operating the loader is normal, and best of all, the loader operates smooth, and fast! Here is a link to a video series, this is the part where I start working the loader problem, so you can see the before/after:

Strange noise from loader valve

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