t190 hydraulic failure

I have a t190 with about 2500 hours on it. It is a pedal machine with a BICS valve. We were using it to load some light sand and in the course of an hour it went from lifting and dumping fine to barely being able to get the bucket off the ground. We parked it and the next morning replaced the hydraulic filter and tried again. This time it worked fine for about an hour, then it went back to barely functioning. The hydrostatic drive works fine, so we were able to get it back to the shop where I almost couldn't get the bucket up to prop in position. I looked it over and at that point I might as well have been looking inside someone's skull for what I knew about it. I am a half decent mechanic but failed to get to the bottom of the problem, so I took it to Bobcat and paid for a diagnosis. They said that besides a new seat cover and headlight needed!, that my hydraulic pump was putting out only 1800psi with no info on flow rates. I took the machine home and am not convinced that with the pump putting out that much pressure it would be unable to raise an empty bucket. Could the problem be in the BICS? or does someone have another idea?

I would lean towards pump. 1800 psi max pressure alone is crap, spec is 3300 psi. That far below and it can not be adjusted up pretty much screams pump. The dealer should have down a direct pump test which plumbs the flowmeter in between the pump and vavle to verify for sure. BICS has nothing to do with your problem.

Bobcatdan said:

I would lean towards pump. 1800 psi max pressure alone is crap, spec is 3300 psi. That far below and it can not be adjusted up pretty much screams pump. The dealer should have down a direct pump test which plumbs the flowmeter in between the pump and vavle to verify for sure. BICS has nothing to do with your problem.

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Being a bobcat novice has left me at a severe disadvantage. At the time I didn't know enough to demand a flow rate which now that I do know seems rudimentary. I realize that the max psi is 3500psi, but I can't help thinking that even with the measly 1800 one would expect to be able to raise a bucket, not have it barely make it at full throttle. I guess I'm jaded by my old John Deere track loader that has a max psi of 1300 and can lift 5000lbs quickly and easily. Am I correct in assuming that the low pressure had to have been accompanied by an incredibly low flow rate to cause this?

Philosaw said:

Being a bobcat novice has left me at a severe disadvantage. At the time I didn't know enough to demand a flow rate which now that I do know seems rudimentary. I realize that the max psi is 3500psi, but I can't help thinking that even with the measly 1800 one would expect to be able to raise a bucket, not have it barely make it at full throttle. I guess I'm jaded by my old John Deere track loader that has a max psi of 1300 and can lift 5000lbs quickly and easily. Am I correct in assuming that the low pressure had to have been accompanied by an incredibly low flow rate to cause this?

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Basic hydraulic lesson here. Pressure equals power. Flow equals speed. You need both to do something. The problem you have is you have squat for flow. Pressure isn't effected much by rpm. Flow is directly effect by rpm. That is why you have to run it full bore to get the arms to move. The pump at that rpm is squeaking out just enough to do something. Also pressure settings are not unverisal. Machines are designed to work at certain pressures. Even if you had half way decent flow, at 1800 psi, the unit would be incredibly weak because its designed to max at 3300 psi. I will throw one other thing at you. When you check system pressure, you are really setting relief pressure. If the dealer tried adjusting the relief and 1800 psi is all it would do, that alone pretty much condemns the pump. I have seen a T190 push close to 6,000 psi at the aux couple due to a very out of adjustment relief valve. That explained why the old pump was toast at 130 hours. The really kicker, the customer gets it back and complains it doesn't have the power it before. I bet before at 6,000 psi, that unit went like a raped ape.

Bobcatdan said:

Basic hydraulic lesson here. Pressure equals power. Flow equals speed. You need both to do something. The problem you have is you have squat for flow. Pressure isn't effected much by rpm. Flow is directly effect by rpm. That is why you have to run it full bore to get the arms to move. The pump at that rpm is squeaking out just enough to do something. Also pressure settings are not unverisal. Machines are designed to work at certain pressures. Even if you had half way decent flow, at 1800 psi, the unit would be incredibly weak because its designed to max at 3300 psi. I will throw one other thing at you. When you check system pressure, you are really setting relief pressure. If the dealer tried adjusting the relief and 1800 psi is all it would do, that alone pretty much condemns the pump. I have seen a T190 push close to 6,000 psi at the aux couple due to a very out of adjustment relief valve. That explained why the old pump was toast at 130 hours. The really kicker, the customer gets it back and complains it doesn't have the power it before. I bet before at 6,000 psi, that unit went like a raped ape.

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Thanks Bobcatdan. That makes perfect sence. I've had a pump on order for a month now and will look forward to getting it back in. Do you think I'd be foolish to go through the control valve while I'm waiting? I had taken it out when the Bobcat mechanic left me unconvinced. It has no leaks. Thanks again.

Philosaw said:

Thanks Bobcatdan. That makes perfect sence. I've had a pump on order for a month now and will look forward to getting it back in. Do you think I'd be foolish to go through the control valve while I'm waiting? I had taken it out when the Bobcat mechanic left me unconvinced. It has no leaks. Thanks again.

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I guess it wouldn't hurt to do the spool seals because they will leak at some point. That said, it may be a can of worms you don't want to open. When somebody says reseal the vavle, all you are doing is replacing 4 seals, two on the lift spool and tilt spool. No reason to touch the aux spool because it never leaks. If you do, pay extremely close attention to the way the seals go in. If put in backwards, they will leak badly in about 5 minutes. Also they can be easy to tear installing, once again will leak badly. If you have a standard foot control machine, the lift spool has a detent on it. Inside are little BBs loving refered to by all that know them as god damn it balls. They can be real ball busters, especially if you don't have the special pliers that makes the job bearable. Have I scared you yet. Personally I wouldn't bother if its not leaking. The vavle can be done in the machine when it does leak, I never pull them out.

Bobcatdan said:

I guess it wouldn't hurt to do the spool seals because they will leak at some point. That said, it may be a can of worms you don't want to open. When somebody says reseal the vavle, all you are doing is replacing 4 seals, two on the lift spool and tilt spool. No reason to touch the aux spool because it never leaks. If you do, pay extremely close attention to the way the seals go in. If put in backwards, they will leak badly in about 5 minutes. Also they can be easy to tear installing, once again will leak badly. If you have a standard foot control machine, the lift spool has a detent on it. Inside are little BBs loving refered to by all that know them as god damn it balls. They can be real ball busters, especially if you don't have the special pliers that makes the job bearable. Have I scared you yet. Personally I wouldn't bother if its not leaking. The vavle can be done in the machine when it does leak, I never pull them out.

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6,000 PSI is just insane. The hoses aren't rated for that, i feel sorry for that poor machine, the suffering it must have had to put up with.
Agreed, if it ain't leaking or isn't leaking enough to be an issue, leave it be. I have spent days trying to fix a chaincase leak on a 743. I never did get it totally fixed, i just let it go as it was, just a drop here and there but some times you need to know when to walk away.

Tazza said:

6,000 PSI is just insane. The hoses aren't rated for that, i feel sorry for that poor machine, the suffering it must have had to put up with.
Agreed, if it ain't leaking or isn't leaking enough to be an issue, leave it be. I have spent days trying to fix a chaincase leak on a 743. I never did get it totally fixed, i just let it go as it was, just a drop here and there but some times you need to know when to walk away.

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Thanks. It's not too hard to talk me out of that job! I've been reading the manual, staring at it and sweating for a week now.

Philosaw said:

Thanks. It's not too hard to talk me out of that job! I've been reading the manual, staring at it and sweating for a week now.

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youre pump crapped and shrapnled the sys. hell yea clean the control valve replace main relief as well as pump. may even clean charge valve. case drains flush and fill and do it again

7LBSSMALLIE said:

youre pump crapped and shrapnled the sys. hell yea clean the control valve replace main relief as well as pump. may even clean charge valve. case drains flush and fill and do it again

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I'd look to see how much metal is in the system first. Gear pumps are funny critters and dont need to destroy themselves to stop working. I have replaced a few that looked to have minor wear. The big question is does he have power bob tach and does that still work? If it does, the isn't enough metal to hurt anything. If there is a ton of metal, replacement of the cooler and flushing are needed. At least change hydraulic filters with a new pump.

Bobcatdan said:

I'd look to see how much metal is in the system first. Gear pumps are funny critters and dont need to destroy themselves to stop working. I have replaced a few that looked to have minor wear. The big question is does he have power bob tach and does that still work? If it does, the isn't enough metal to hurt anything. If there is a ton of metal, replacement of the cooler and flushing are needed. At least change hydraulic filters with a new pump.

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I do have the valve out and separated the BICS from it with no sign of metal at all. Also I don't have a bob tach. I have drained the system and my next step is to clean the case drain filters. If they are clean, can I assume that I don't have a metal problem. I could also disect the hydraulic filter to see if there's any metal in there as well, or perhaps bring in an oil sample for testing.

Philosaw said:

I do have the valve out and separated the BICS from it with no sign of metal at all. Also I don't have a bob tach. I have drained the system and my next step is to clean the case drain filters. If they are clean, can I assume that I don't have a metal problem. I could also disect the hydraulic filter to see if there's any metal in there as well, or perhaps bring in an oil sample for testing.

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I was just reading up on any threads I could find here on t190 hydraulics and came across a discussion about High Flow pumps. My machine is a high flow which makes me wonder if that function is involved in such a sudden loss of power? I guess the bobcat mechanic would have told me if it was...maybe.

Philosaw said:

I was just reading up on any threads I could find here on t190 hydraulics and came across a discussion about High Flow pumps. My machine is a high flow which makes me wonder if that function is involved in such a sudden loss of power? I guess the bobcat mechanic would have told me if it was...maybe.

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where are we at on this case guys? does it warrant further diccusion?

7LBSSMALLIE said:

where are we at on this case guys? does it warrant further diccusion?

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BCD. put hyds in black and white. there a[nt no gray.

7LBSSMALLIE said:

BCD. put hyds in black and white. there a[nt no gray.

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I reinstalled the valve body and installed the new pump as well. I should be able to test it out in the next day or so. I'm hoping that all will be well even though my confidence is low. Thanks for all the replys. I'll post the results soon.

Philosaw said:

I reinstalled the valve body and installed the new pump as well. I should be able to test it out in the next day or so. I'm hoping that all will be well even though my confidence is low. Thanks for all the replys. I'll post the results soon.

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Before you use it, check and set the relief pressure. If the vavle was out of adjustment high before, that could easily caused your pump failure. Not setting to 3300 psi could kill your new pump.

Bobcatdan said:

Before you use it, check and set the relief pressure. If the vavle was out of adjustment high before, that could easily caused your pump failure. Not setting to 3300 psi could kill your new pump.

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Thanks bobcat Dan. I nearly forgot about that. I did get it running this evening, firing it up to look for leaks which went well. I did hear a squealing coming from near the hydraulic pump and was definitely hydraulics, which quit before I could shut it down. All hydraulics function properly. The total run time was probably 2 to 3 minutes. Could the squeal be from air?

Philosaw said:

Thanks bobcat Dan. I nearly forgot about that. I did get it running this evening, firing it up to look for leaks which went well. I did hear a squealing coming from near the hydraulic pump and was definitely hydraulics, which quit before I could shut it down. All hydraulics function properly. The total run time was probably 2 to 3 minutes. Could the squeal be from air?

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Probably. Watch the fluid level. It can take a few top offs to get it correct.

Bobcatdan said:

Probably. Watch the fluid level. It can take a few top offs to get it correct.

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Spent the day fixing the leaks that I thought i didn't have. Fired it up and no squealing and no problems. Checked the pressure and it was just under 3000 psi. All in all it was a great way to know your bobcat! I'm no longer intimidated by it and finding this resource was another benefit to an otherwise difficult experience. Thanks again.