Branson 3510i hydraulic problems

btsavage · Jul 18, 2015

I have a 3510i that has developed a hydraulic problem. The whole system has weakened drastically over the last few hours of use. Right now if it's not at least at 2200 rpm, it will not raise the empty loader bucket. The backhoe (Branson 7620) moves very slowly and again not at all at low rpm. I tried changing the hyd filter (OEM filter) and topping off the fluid but it did not help.
I'm in the middle of a project and need to get back up and running. Any advice appreciated!

oldnslo · Jul 18, 2015

The pump flow is escaping at a low pressure some where. This could be due to a relief valve stuck open. Does any part of the system seem to get hot faster? Do hear any sounds like fluid spraying, or squealing sound any where in he rear end?

Did you notice any change in noise when the system started slowing down?

btsavage · Jul 19, 2015

I did notice a whining noise when operating the loader. I also noticed the loader valve is hot. i wasn't sure if that was normal. Also. Something I did notice is that rolling the bucket seems a lot faster than the lift. Is there s relief valve on the loader valves? Is there a way to isolate it and determine if that is the problem?

J_J · Jul 19, 2015

If your loader valve has regen, the bucket will be much faster because you pump flow plus the other side of the cyl flow.

Your bucket curl up speed should be normal.

Whining noise sounds like relief valve, but that only comes on when you exceed the set relief pressure and that pressure is caused by load.

btsavage · Jul 20, 2015

Ok, I think I was barking up the wrong tree. I noticed that the loader control valve is "sticking" and it got stuck in the float position. Took a pretty good whack on the control lever to get it out of the float position.

I'm now thinking that I have no pressure because the loader control valve is bad??

Anyone have experience rebuilding one of these? Source for parts?

J_J · Jul 20, 2015

Install a $30, LF hyd gauge 3000 to 5000 psi test unit, and check the pressure .

Install the gauge in a tee in the IN port of the loader valve.

btsavage · Jul 20, 2015

I just talked to the Branson dealer and he suggested the same thing. I've made some calls to NAPA and such and can't find a gauge locally. I really need to get this thing back to work.

I have a backhoe on the tractor and it's operating, but very slowly and no pressure. It operates off the hydraulic rear remote. Am I correct in thinking that if it's a problem with the loader control valve that the backhoe should still operate normally? I guess that I'm not sure how it works.

J_J · Jul 20, 2015

I believe your tractor has a open center hyd system, and therefore the pump flow is flowing through all valves in series.

The pump volume is dictated by your engine speed.

So if your tractor is running full rpm, you should be pumping max pump flow.

A hyd valve controls how much flow goes into a cyl, so if you have full lever, the full pump flow should go into the cy.

Pressure is something else, and the pressure is developed by the cyl trying to do work by the load imposed on it.

A bad relief valve can divert the flow.

A weak pump will not pump expected flow, and if no hyd, the pump shaft could be sheared off.

Have you checked for flow by removing a hose?

btsavage · Jul 20, 2015

No, I have not removed a hose to check for flow. Also, at idle, the hydraulics will not move. I have to have about 2000 RPM to get the loader to move at all.

J_J · Jul 20, 2015

Some of your flow may be diverted to the steering circuit using a priority valve, and you have to have more rpm for the hyd to work.

Say you had 10 GPM, and the steering required about 3 GPM. If your system does work by a priority valve, the steering will get the first 3 GPM, and if your engine rpm is low, that maybe all the pump is pumping.

Run the engine at max and see if the hyd improve.