bobcat 630 hydraulic power loss

[lucaslandscape]

heres my story in a nutshell...i have good power to the wheels when im not using the lift and tilt cylinders.if i get a good bucket full of dirt i cant lift it.if i am trying to lift to long i loose power to the wheels to the point if im on a hill pushing levers full foward i would go backwards. i put a gauge on the auxiliary ports and i get over 2000 psi for a split second and quickly drops to 1600psi and sometimes even lower.today i even had a full bucket and started raising it and got to chest height and wouldnt go any higher,so i let off the raise pedel and quickly hit it again then let offand hit it a few more time each time going up a little bit till it was up about 6ft or so.then i held it in the up position for a few seconds and it was going down but the pump sounded like it was straining.i just got this machine a few months ago ...the guy i got it from replaced the pump and played with the control valve.i cleaned the bronze filter too.what could be the problem?i have the manual and it said to check the cylinders for by-passing in them and that check looks good.i played with the main relief valve in the control valve turning it all the way in and still no power to the lift cylinders.help!!!! thanks in advance kyle

 

[Bobcatdan]

I'm thinking you are pulling air on the suction side or maybe have a charge prsssure problem. Fluid level good? For the most part, drive and lift are actually seperate system. Any idiot lights on?

 

[lucaslandscape]

I'm thinking you are pulling air on the suction side or maybe have a charge prsssure problem. Fluid level good? For the most part, drive and lift are actually seperate system. Any idiot lights on?

The fluid level is good and my lights don't work....it seems like its air when i lift the arms without a load it has small hopps like air bubbles.but how do I find a suction leak and where is the most common place for such a leak.also when you say suction side are you. Refering to the side before the pump? (charge pressure)

 

[jerry]

The fluid level is good and my lights don't work....it seems like its air when i lift the arms without a load it has small hopps like air bubbles.but how do I find a suction leak and where is the most common place for such a leak.also when you say suction side are you. Refering to the side before the pump? (charge pressure)

Make sure your aux hyd is not being engaged at all too, bobcats do funny things if the aux hyd are active. If I remember right there is a relief valve and spring in the rear on the port block. When I redid the pumps on the 632 I replaced the spring and it did bring the charge pressure up some. The new spring was just slightly longer , would guess the old one had lost length due to time.

 

[Bobcatdan]

Make sure your aux hyd is not being engaged at all too, bobcats do funny things if the aux hyd are active. If I remember right there is a relief valve and spring in the rear on the port block. When I redid the pumps on the 632 I replaced the spring and it did bring the charge pressure up some. The new spring was just slightly longer , would guess the old one had lost length due to time.

That is a good point about the aux, but that shouldn't effect drive unless the engine is weak.

 

[lucaslandscape]

That is a good point about the aux, but that shouldn't effect drive unless the engine is weak.

The aux Hyd. Is off the engine seems to have plenty of power...going into a pile tires spin without killing the engine ....climbs pretty steep hills or the ramps on the trailer at a little more than an idle.

 

[lucaslandscape]

Make sure your aux hyd is not being engaged at all too, bobcats do funny things if the aux hyd are active. If I remember right there is a relief valve and spring in the rear on the port block. When I redid the pumps on the 632 I replaced the spring and it did bring the charge pressure up some. The new spring was just slightly longer , would guess the old one had lost length due to time.

I had the main relief valve out and apart.i put a heavier spring in it but didn't seem to help. The cold weather relief valve in the port block seem to be ok but have nothing to test or compare it to.do you know where i can get one and how much that spring is.what if I put a spacer in there to put a little extra pressure on the spring. I have another thing I want to throw out at you guys the bronze filter in the port block...my manual says there is a o-ring on the end of it.mine someone had it out and looks like there is blue RTV or something on the end.also what would happen if I took the bronze filter out for a "test run" if it gets better my filter is bad is it doesn't then it's something else

 

[lucaslandscape]

I had the main relief valve out and apart.i put a heavier spring in it but didn't seem to help. The cold weather relief valve in the port block seem to be ok but have nothing to test or compare it to.do you know where i can get one and how much that spring is.what if I put a spacer in there to put a little extra pressure on the spring. I have another thing I want to throw out at you guys the bronze filter in the port block...my manual says there is a o-ring on the end of it.mine someone had it out and looks like there is blue RTV or something on the end.also what would happen if I took the bronze filter out for a "test run" if it gets better my filter is bad is it doesn't then it's something else

Update.....k I was feeling a little adventurous so I took out the bronze filter and put a washer in the return line from the control valve also put a gauge in the port block since my idot lights dont work?.. .on start up gauge said 160psi after it warmed up it went down to 140psi went for a test bucket and seemed a little better but hardly worth mentioning.the gauge I put on the pump only reached a peak of 1500-1600 psi hard to read because it's not steady far cry from the 1950 the manual says its should be