Bucket tilt ok up/down not so much

[mike11]

Quick question guys, 853 model
I recently replaced my spool valve seals, today I used the machine for the first time to pull my truck out of my yard, driving is fine bucket tilt is strong it’ll lift the front of the machine, up//down is weak, without the bucket it’ll go right up, with the bucket on it’ll barely move it, it bumps and that’s it. Could that spool be messed up or could there be air in the up/down circuit from the valve seal change ???
Thanks

 

[mike11]

Went down and did it a lil poking around today, warmed the machine up, hooked up the bucket and it took it all the way up 1 time no problem, after that it would only raise it about a 1 ft then less and less each time. After taking the bucket off it’ll raise the arms up and down no problem but not with the weight of the bucket on. Kind of puzzling

 

[FJRDarksider]

Did it behave this way prior to the spool seal replacement? could be a bad relief valve. I would first look at the linkages though. May have become misaligned after reinstallation.

 

[mike11]

Did it behave this way prior to the spool seal replacement? could be a bad relief valve. I would first look at the linkages though. May have become misaligned after reinstallation.

I never had the bucket on it before the spool seals, I picked this machine up a few weeks back, had it shipped to me. This machine’s and absolute mess, previous owner removed all boss harness and controller as well as aux hyd controller and harness, had only 2 mechanical gauges hooked up in it. Wanting to get all that back together while digging and saw the spools leaking that was the first order of biz was fix the oil leak then go from there with the electrical and everything else. Is that valve for the up down spool right on the main control valve ? Do they stick or do they fail. Now I also want to mention it’s in the upper 20s here, could it be bypassing cause the oils cold and thick ?? I did let it run for 20 min before checking it, yesterday it ran for prob an hour before I first noticed it
I didn’t see anything off with the linkages, on the pedal side bolt is back in the same hole as it was before disassembly, on the valve side there’s only one way it can go together.

 

[FJRDarksider]

A leaky spool from the seals shouldn't affect operation. Damaged spool would be unlikely I think as well, which is why I am leaning towards a bad pressure relief valve on the controller. Did you disassemble and change every seal on it and not just the spools? It operates fine until the oil warms which may cause more fluid to pass.......especially under load. I'm taking a guess though.....

 

[FJRDarksider]

or a bad hydraulic pump.........contaminated oil.

 

[mike11]

or a bad hydraulic pump.........contaminated oil.

I only changed the blue seals on the outer ends of the spools, spools looked fine and not damaged. If the pump was damaged wouldn’t that also cause a weak tilt ?? Tilt is strong enough to pick the front of the machine off the ground no problem

When I did the spools I drained the oil from the tank and replaced with new, looked ok I didn’t see anything funky with it it was clean n clear

 

[ward]

Stop everything your doing and do a hydrualic pressure test to see if you have internal leaking on the cylinders, you will need a 5000 psi gauge as you always want a gauge that is 85 to 100 % greater then the system you are checking so a system that runs between 2000 psi and 3000 pas falls with in a 5000 psi gauge and see what pressures you get when you run the bucket tilt all the way forward and tilt all the way back , then go to the lift cylinder and repeat process, you should be able to T in to one of the fittings at the hydrualic cylinders this is going to tell us if you have a bad pump or relief valve, remember it does not take much pressure to lift the fron of the machine due to most of the weight is on the back tires already, the question is if you put a block under the machine will it lift the whole unit off the ground, it should lift the whole unit up so you could remove the tires after blocking the unit up

 

[mike11]

Stop everything your doing and do a hydrualic pressure test to see if you have internal leaking on the cylinders, you will need a 5000 psi gauge as you always want a gauge that is 85 to 100 % greater then the system you are checking so a system that runs between 2000 psi and 3000 pas falls with in a 5000 psi gauge and see what pressures you get when you run the bucket tilt all the way forward and tilt all the way back , then go to the lift cylinder and repeat process, you should be able to T in to one of the fittings at the hydrualic cylinders this is going to tell us if you have a bad pump or relief valve, remember it does not take much pressure to lift the fron of the machine due to most of the weight is on the back tires already, the question is if you put a block under the machine will it lift the whole unit off the ground, it should lift the whole unit up so you could remove the tires after blocking the unit up

I have lifted the front to remove a tire recently with the bucket on tilting it down, I have a press test kit coming today I’m planning on doing some pressure testing later today.

 

[brdgbldr]

I have lifted the front to remove a tire recently with the bucket on tilting it down, I have a press test kit coming today I’m planning on doing some pressure testing later today.

What WARD was saying about removing a tire. You should be able to block the back of the machine and the use the bucket to raise the entire machine so that all 4 tires are off the ground.

 

[mike11]

What WARD was saying about removing a tire. You should be able to block the back of the machine and the use the bucket to raise the entire machine so that all 4 tires are off the ground.

Oh that I didn’t do. That makes sense they are light in the front

 

[mike11]

Stop everything your doing and do a hydrualic pressure test to see if you have internal leaking on the cylinders, you will need a 5000 psi gauge as you always want a gauge that is 85 to 100 % greater then the system you are checking so a system that runs between 2000 psi and 3000 pas falls with in a 5000 psi gauge and see what pressures you get when you run the bucket tilt all the way forward and tilt all the way back , then go to the lift cylinder and repeat process, you should be able to T in to one of the fittings at the hydrualic cylinders this is going to tell us if you have a bad pump or relief valve, remember it does not take much pressure to lift the fron of the machine due to most of the weight is on the back tires already, the question is if you put a block under the machine will it lift the whole unit off the ground, it should lift the whole unit up so you could remove the tires after blocking the unit up

Ward I didn’t have enough fittings here in my assortment big enough to T in at the lift cylinder, I’ll get some tomorrow if I can they look like -10 is that correct ?

 

[ward]

I have worked on all kinds of construction equipment, however I have never had to replace hydrualic hoses on a Bob Cat we were just getting them in when I left the rental industry in 2005 so I would have no idea, however they normaly are stamped on the fittings some times on the nuts of the hose, I went back and reread the first post and I believe that you are going to find that the pump or relief valve is bad, hopefuly the relief valve as it will be a easy fix, to be safe you could take a hose off and take with you. all states ag parts if it is the pump, I have used them for farm tractors however I would check to see if it is a new pupm or usedas they sometimes have both,

 

[mike11]

Unable to T into the cylinders today or get the fittings I did wire up my aux hyd ,when I got this machine it had all electronics and wiring harnesses removed. I now have the aux controller and harness in as it should be. When activated I can hear the engine strain, I only had a coupler here I tap off of the male quick connect but flipping the toggle on the joystick I should be able to divert flow from the male coupler yes ???? After doing that there was hardly any back pressure in the coupler.
Looking at the control the Pres relief for the lift circuit has a T going to the apitech, what is the reason for that? Did I need to have anything activated on the apitech to send fluid to my aux or is that only for hi flow ??
Thanks

 

[mike11]

The lock solenoid was previously hooked up to a toggle switch which is fine that is now the present operate switch, I believe the pump is string based on how it strains when trying to do anything if it’s not activated I could be wrong if so please correct me.

 

[mike11]

I have worked on all kinds of construction equipment, however I have never had to replace hydrualic hoses on a Bob Cat we were just getting them in when I left the rental industry in 2005 so I would have no idea, however they normaly are stamped on the fittings some times on the nuts of the hose, I went back and reread the first post and I believe that you are going to find that the pump or relief valve is bad, hopefuly the relief valve as it will be a easy fix, to be safe you could take a hose off and take with you. all states ag parts if it is the pump, I have used them for farm tractors however I would check to see if it is a new pupm or usedas they sometimes have both,

I’d take a shot at the relief valve now, it’s the cheapest of the two and if it’s not one it’s the other. You’re talking about the one for the lift circuit ? Not the main correct

 

[mike11]

I think I stumbled on my issue, the manual relief valve down by the seat has a bent shaft, I’m sure some Neanderthal in the past ripped the front panel out without removing the button during this machines previous surgery. How I see it is if that button was raised as they were muscling the front panel out and bent it while it was up it’ll never completely seat. It’s obviously bent turning the knob you can see it spins out of round. Also the pic of the new one on bobcats website appears to have less shaft out of the body at rest compared to mine. At this point I would say it’s either that or a lift circuit pres relief, but am leaning toward this valve. I have one ordered it’ll be here Thursday. Let’s see what happens but I’m feeling good about this find.

 

[mike11]

I also ordered a lift circuit relief I’m 99% sure one of them will do it if not it’s gonna be a nice expensive pump.

 

[brdgbldr]

I think I stumbled on my issue, the manual relief valve down by the seat has a bent shaft, I’m sure some Neanderthal in the past ripped the front panel out without removing the button during this machines previous surgery. How I see it is if that button was raised as they were muscling the front panel out and bent it while it was up it’ll never completely seat. It’s obviously bent turning the knob you can see it spins out of round. Also the pic of the new one on bobcats website appears to have less shaft out of the body at rest compared to mine. At this point I would say it’s either that or a lift circuit pres relief, but am leaning toward this valve. I have one ordered it’ll be here Thursday. Let’s see what happens but I’m feeling good about this find.

Good catch with the manual relief valve. You have to lift and twist that valve to get it to work. I’m wondering if maybe it is stuck twisted and maybe you could try to untwist it to get it to seat.

If I remember correctly to open the valve you lift and then twist clockwise.

 

[mike11]

Good catch with the manual relief valve. You have to lift and twist that valve to get it to work. I’m wondering if maybe it is stuck twisted and maybe you could try to untwist it to get it to seat.

If I remember correctly to open the valve you lift and then twist clockwise.

Pretty sure one of these will fix it, the man relief needs replaced either way.