I am working on an old Bobcat 310. It won't lift or tilt. We assume the hydraulic pump is bad. I've tried a few things. 1) took the pump off and ran it with a drill. It would pull fluid out of a 5 gallon bucket. 2) Added a T fitting on the inlet side of the pump and a new rubber line. We used a hand pump to prime and add fluid while trying to raise the arms. The arms would raise as long as we had pressure on the hand pump (slowly). 3) blew air back through the filter and into the storage tank and heard it gurggle. We have concluded the pump is bad since it wouldn't proved pressure even when we primed it. if you have other thoughts let me know before I buy a new pump.
310 Hydraulic Pump
- Thread starter bttpe
- Start date
It's almost as if you have a restriction. If you are starvign the pump of fluid, it will not generate any pressure, with you hand pump, i assume you are giving it a little extra pressure to pump and that's what makes it lift the arms.
The ideal way is to get it bench tested, it's hooked up with a fluid supply and a pressure gauge, they spin it up and restrict the output and see what the pressure vs flow does.
Without seeing it i can't condem the pump, i'd look at a possible suction restriction first.
Is the oil foamy at all?
The ideal way is to get it bench tested, it's hooked up with a fluid supply and a pressure gauge, they spin it up and restrict the output and see what the pressure vs flow does.
Without seeing it i can't condem the pump, i'd look at a possible suction restriction first.
Is the oil foamy at all?
Thanks I'll look at the oil and will replace the filter today. We pressurized the oil the system yesterday by using compressed air where the oil fill hole is. That would very slowly help raise the arms. We are going to look for leaks today on the inlet side between the pump and the tank. I'll post an update at the end of the day. The oil looks good - not cloudy or foamy.
That does seem to indicate that the issue could indeed be the pump. The extra pressure from the compressed air, you said it made the arms lift slowly, that sounds like it just gave a little extra pressure to the weak pump.
Normally, if the filter is plugged, it will make the oil foam up.
We pulled the pump out again and will run it down to our Bobcat dealer and see if they will test it. I'll let you know what I find out.
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Not sure if they have the gear to do it outside the machine, a hydraulic shop should have a test bench to be able to do it if bobcat can't.
OK the whole thing is a learning experience. Turns out it's not a problem with the pump. Just bad orings in the control valve. Specifically the pressure relief valve. It's not perfect yet we bought orings from a local Hydraulic Shop $15 vs $274 from Bobcat dealer. Burned up the old belts driving the pump (probably 30 year old belts) once the hydraulic pump saw load. Have belts on order and will hopefully close this thread out with success. More later.
Good to hear it.
Your locak hyraulic seal shop is your friend, they can't do every seal, but they can generally work something out that is way cheaper.
Hammerhead63
Member
- Joined
- Mar 20, 2021
- Messages
- 12
Good evening bttpe. Having a similar issue with my 310. How were you able to Devine the control valve issue? With mine, it will lift but I have to keep bumping it. If I roll the bucket whil lifting it seems to actually perform a bit better which makes me think I may also have a controller issue. Did you rebuild it yourself or have a shop do it for you? Thanks, Doug
