Kind of a weird problem, I have a 2009 Bobcat S300 that will lift the pins when the button is pressed but will not lower the pins when the button is pushed down. I first removed the cylinder and tried moving it by itself thinking one of the handles could be binding but it didn't change I removed the base end line and plugged per the service manual and found the seals were worn so I rebuilt the cylinder. I tested once again and there was no oil leaking past the seals after I put new seals in. I then moved to the power bobtatch control block back by the pump. I checked the solenoids to make sure the nut hadn't backed off causing one of the solenoids to fall off as I had seen before. The nut was tight. I then removed the nut and reversed the solenoid pack. When I press the down button the bobtatch now moves up and when I press the up I have the same problem where the bobtatch won't move without tilting or curling at the same time. I'm thinking it is a solenoid problem but both ohm out the same. I'm curious if it could be a problem with the shaft that the solenoids slide or possibly some debris inside the block stopping it from flowing properly without adding the additional pressure from tilting or curling? Any suggestions are appreciated. I'll make sure to post exactly what was wrong once fixed.
09 S300 Power Bobtach will go up but not down without curling or tilting at same time
- Thread starter bobcatguy
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The pin movement isn't the problem. I unhooked the cylinder and the levers work easily. This seems to be a hydraulic related problem. I've removed both solenoid coils from the stack and checked resistance to make sure the coils are good. Both checked the same. I'm removing the block to see if there is a blockage or if the shaft that the solenoids move is stuck. I will report back with what I find.
A little more info. I removed the line from the base end of the power quick attach cylinder, attached a clear hose and then pressed the down switch. There was oil flowing out of the line into a bucket but the flow didn't appear to be with much pressure. I talked to a dealer who suggested I needed to replace my quick attach hydraulic control block ($700 OUCH) He thinks the stem for the solenoid is bad but It doesn't appear there is anything wrong with it by eye. Thoughts??
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are your auxiliary hydraulics stuck on? thats what it sounds like to me
Not on an 09. They go on and off when the machine is shut down.
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doesn't mean a relay can't be stuck open. when aux hydraulics are on without an attachment it makes lift and tilt act all messed up. it does screwy things.
The power bobtach would be self closing if the aux was stuck on. The reason the bobtach closes when moving other functions is oil is metered automatically to close the bobtach when there is a pressure rise. Basically to keep it from ever opening unwanted. The stem probably has a piece of crap in it and is stuck. Pretty sure it is not available separate so you have to buy the whole. Being mounted directly to the gear pump, the valve catches any crap in the system. It's normally the first symptom a drive motor is failing on a track machine, the power bobtach stops working.
Dan, I removed the stem and cleaned. I tried removing the pressure relief and blowing air through the valve body but when I put it back together it still didn't work. I'm going to have my son press the button for down and check to make sure the coil is energizing. If that checks good, I bought a good used valve from a used parts place and will give that a try. Thanks for your help!
I have never had luck cleaning stems to the point I don't bother. If I feel the stem is the problem, it gets replaced.
I looked at the stem and it didn't appear to be over technical. Pass through center and two small holes. I used a torch tip cleaner for the larger of the two holes and wire for the smaller. I blew air through it and shined a light in the small holes to verify they were cleaned out band both appeared fine. I don't know why bobcat doesn't offer a new stem for the valve rather than offering a new valve if the stem goes bad.
Once you verify you don't have an electrical problem like you said you where going to check, I may have thought of a possibility. Many attachments use a bidirectional stem to control functions. May or may not be the same as the stem on the power bobtach block. In theory it is. Maybe worth a look. I don't why parts are unavailable for the block, its just way it is.
I had my son press the PBT button with the power on, engine off. When he pressed up, there was magnetic field in the up solenoid. When he pressed down, also magnetic field so both solenoids are working. I can also hear the stem moving with the solenoid coils when they are energized. I installed the "good" used block and things went from bad to worse. Now I have absolutely no PBT so that good valve isn't so good. I'm guessing I just pissed away 350 for a truly bad block. When the buttons are pressed with the power on engine not running you can't hear the stem moving at all in either direction. Dan, if you read this I'm wondering if it's not more of a check valve problem than a stem problem. I believe a check valve moves allowing flow to travel to the base end of the cylinder which closes the quick attach.
I can't see the check vavle being the problem on both blocks. Yeah I guess it is possible it cause a problem, but kinda doubt it. Did you swap stems? Maybe your old block has a check vavle problem and the new one a stem problem and you could make one good one. Personally I would not have gambled on a used block. Any piece of crap in the system will get caught and screw of the power bobtach vavle.
It would seem odd to have two valves with check valve problems. I just can't get past the fact that I can hear the stem doing what it's supposed to do. I'm going to do a complete block tear down (short of screws that aren't supposed to be removed) and see if I can do a very thorough cleaning job on one of my blocks. I get a feeling that there's something in the valve that's being blocked. I know there are one or two restrictors inside the valve body that are serviceable so I'm going to look at those and then plug ports and try to blow air through the valve. My concern is that 2000 psi put a blockage in there and 120 psi isn't going to remove it if it's there. I'm not touching that used block until I hear back from the parts place I bought it from. I was a little worried about buying a used block but I've bought lots of used parts and never had any trouble. We'll see if this place I bought this from is as good as Schaefer when they sell a non working part.
Well, I tore the old valve down, cleaned it with carb cleaner and air, cleaned all restrictors and then reassembled the valve and installed. Still no go so...... I bought a new valve, installed it and BAM it works. I have no earthly idea what is wrong with my old valve. You can hear the needle moving with the solenoid coils but something isn't opening allowing flow. Hopefully my work will save someone else a lot of grief in the future.
