1992 LX555 Loss of Propulsion

[92LX555]

This is an older 555 not a 565 so I guess it must be the chain case, it would be hard to miss a reservoir, they are among the largest components on the loader. No one is trying to acuse you of anything, but the last machine I seen without a hyd resercvoir was a 371 bobcat, they were a clutch drive and the hydrauic pump used the chaincase reservoir. Last made in 1977.
If they are using chain case oil, there must be a screen or inlet filter to keep chain and sprocket wear out of the hydro system. You should find where the sender is for the charge pressure warning light and install a 150 psi guage in there. or T it in. The charge pressure light should be off. If its on it would be good to check the actual pressure. No idea on the spec but 100 psi or so...
It is my understanding at times the wheels will not turn at all, does the motor lug down like it is working when this occures or does it just sound normal? It not a bad bearing or something that is binding up? Because the motor would labor in that situation. Will the machine turn the wheels if its up on blocks?.
Do you have anything else there with a hydraulic pump you could hook hoses to the wheel motor and put some pressurre to it to see if it will turn the wheels on the trouble side?
Any competant hydraulic repair shop should have a flow meter the could plump into you hydrostat for the bad side and see what flow and pressure the hydrostat is capable of.
Or could you make so hoses up to flip the motors to the opposite side of the hydrostatic pump without actuall removing the motors?
You need to find a way to narrow down where the problem is.
Also don't rule out asking independant equipment repair shops, locally they are my best bet, for my white equipment anyway. I have never been to my good Bobcat dealer, but they do provide great service on the phone and fax info when needed. So check around until you find one like that.
Ken

I know no one is accusing me anything and all of the ribbing is in good natured. I can take it but like to dish it out more! My unit is a 1992 and I am thinking the same thing you.....this reservoir would be huge and I would remember seeing it. Without being right at the unit to look I can go on the memory for now and I honestly don't believe that it is there. This unit was top of the line in 92 when it was purchased. I am the 2nd owner and the 1st owner was my neighbor who ran it on a diary farm. There is a screen/filter that is located in the cab by the foot controls on the right side of the unit....opposite the dipstick side. (left side if the bucket is at your feet) I am going to hook some gauges up to the pump tonight or tomorrow and see what I have. I am pretty sure the problme is somewhere within the pump. This unit has three pumps....a gear pump, RH pump, and LH pump. The LH pump is the one in question and is towards the rear. There should be a relief valve in the pump that may have failed but I think if it did fail then I would not have enough system pressure to raise the boom. The light comes on but I can still raise it. So the next thing that I think is the coupler between the pump and the motor. If the splines have worn off then it would work but would still have enough pressure to raise the boom? And on occasion a spline would catch which would account for the sudden propulsion that I can occosaionally get. This is my latest theory anyway. One thing I have learned is that with me whatever can go wrong will go wrong and I can never have the simple things to fix. Seems like all of my stuff breaks the most unusual way and never the same way twice. Thanks for tryng to help and I do really really appreciate it!

 

[mllud]

I know no one is accusing me anything and all of the ribbing is in good natured. I can take it but like to dish it out more! My unit is a 1992 and I am thinking the same thing you.....this reservoir would be huge and I would remember seeing it. Without being right at the unit to look I can go on the memory for now and I honestly don't believe that it is there. This unit was top of the line in 92 when it was purchased. I am the 2nd owner and the 1st owner was my neighbor who ran it on a diary farm. There is a screen/filter that is located in the cab by the foot controls on the right side of the unit....opposite the dipstick side. (left side if the bucket is at your feet) I am going to hook some gauges up to the pump tonight or tomorrow and see what I have. I am pretty sure the problme is somewhere within the pump. This unit has three pumps....a gear pump, RH pump, and LH pump. The LH pump is the one in question and is towards the rear. There should be a relief valve in the pump that may have failed but I think if it did fail then I would not have enough system pressure to raise the boom. The light comes on but I can still raise it. So the next thing that I think is the coupler between the pump and the motor. If the splines have worn off then it would work but would still have enough pressure to raise the boom? And on occasion a spline would catch which would account for the sudden propulsion that I can occosaionally get. This is my latest theory anyway. One thing I have learned is that with me whatever can go wrong will go wrong and I can never have the simple things to fix. Seems like all of my stuff breaks the most unusual way and never the same way twice. Thanks for tryng to help and I do really really appreciate it!

I heard they used the chain case as the resevior for the hyd system. this was in models prior to 1994.They shared the same oil. Mike

 

[jerry]

I heard they used the chain case as the resevior for the hyd system. this was in models prior to 1994.They shared the same oil. Mike

Since you have common oil reservoir for the hyd and the hydrostats when you have the chain case open put a couple speaker magnets in there on the bottom to catch metal filings. I think your idea about the drive coupling sounds reasonable, should be able to see it with a inspection mirror and have someone rock the crankshaft so you can watch for movement. On our old bobcat it worked anyway when the u joint was getting worn.

 

[robmints]

I know no one is accusing me anything and all of the ribbing is in good natured. I can take it but like to dish it out more! My unit is a 1992 and I am thinking the same thing you.....this reservoir would be huge and I would remember seeing it. Without being right at the unit to look I can go on the memory for now and I honestly don't believe that it is there. This unit was top of the line in 92 when it was purchased. I am the 2nd owner and the 1st owner was my neighbor who ran it on a diary farm. There is a screen/filter that is located in the cab by the foot controls on the right side of the unit....opposite the dipstick side. (left side if the bucket is at your feet) I am going to hook some gauges up to the pump tonight or tomorrow and see what I have. I am pretty sure the problme is somewhere within the pump. This unit has three pumps....a gear pump, RH pump, and LH pump. The LH pump is the one in question and is towards the rear. There should be a relief valve in the pump that may have failed but I think if it did fail then I would not have enough system pressure to raise the boom. The light comes on but I can still raise it. So the next thing that I think is the coupler between the pump and the motor. If the splines have worn off then it would work but would still have enough pressure to raise the boom? And on occasion a spline would catch which would account for the sudden propulsion that I can occosaionally get. This is my latest theory anyway. One thing I have learned is that with me whatever can go wrong will go wrong and I can never have the simple things to fix. Seems like all of my stuff breaks the most unusual way and never the same way twice. Thanks for tryng to help and I do really really appreciate it!

92 i'm not trying to be a jerk by saying what is the front, I'm trying to keep it straight. It's like talking about an old Beetle, the front is the front I guess it is a bad habit I got from the John Muir books. Makes sense that they would use common oil, except for the dirt that may be in the oil. But it would seem the engine would drive one pump and have 2 wheel motors. It has separate pumps for each wheel motor? The linkage to the lh control didn't fall off, did it? Sorry for seeming like a jacka$$, it was not intentional.

 

[Land-Tech]

92 i'm not trying to be a jerk by saying what is the front, I'm trying to keep it straight. It's like talking about an old Beetle, the front is the front I guess it is a bad habit I got from the John Muir books. Makes sense that they would use common oil, except for the dirt that may be in the oil. But it would seem the engine would drive one pump and have 2 wheel motors. It has separate pumps for each wheel motor? The linkage to the lh control didn't fall off, did it? Sorry for seeming like a jacka$$, it was not intentional.

The old john deere's from the 70's used the chain case to hold the hydralic fluid. there was a tube that connected both chain cases with a drain fitting to drain oil. I remember that there was a primary and secondary filters in the system to make sure things got clean. scott

 

[skidsteer.ca]

The old john deere's from the 70's used the chain case to hold the hydralic fluid. there was a tube that connected both chain cases with a drain fitting to drain oil. I remember that there was a primary and secondary filters in the system to make sure things got clean. scott

The loader boom uses the pump on the back of the hydrostats 2 pump sections, so there is a good chance a hydraulic problem in one of the wheel drives won't affect the loader. It could be a mechaincal failure in the drive on that side or a hyd failure in the hydropump or motor.
I don't believe it is in the "charge pressure" as the opposite side works fine. But the warning light should not be on either.
Ken

 

[92LX555]

92 i'm not trying to be a jerk by saying what is the front, I'm trying to keep it straight. It's like talking about an old Beetle, the front is the front I guess it is a bad habit I got from the John Muir books. Makes sense that they would use common oil, except for the dirt that may be in the oil. But it would seem the engine would drive one pump and have 2 wheel motors. It has separate pumps for each wheel motor? The linkage to the lh control didn't fall off, did it? Sorry for seeming like a jacka$$, it was not intentional.

Robmints....No worries my friend you did not come across as being a jerk, just having some fun. The fact that I can run one side really rules out anything to do with dirty fluid, etc. I did also check last night for another resvervoir and there is not one. The only two that it ahs are tha chain case reservoirs. I am kind of shocked at some of the comments becasue my understanding was that this machine was pretty much state of the art when it was built in 92. But it sounds like some of the technology, like not having a reservoir seperate from the chain case, is old technology. This machine has been a solid machine for me and I abuse the hell the out of it. I pulled the seat last night to check out the pumps. The unit has a gear pump towards the front, a RH drive pump behind it and the LH drive pump behind it. The LH drive pump (the one in question) has a T fitting off of the top of it. I am looking for a set of high pressure gauges to see what the pressure is. I don't know what it should be ready but my guess is at least 2500 PSI and probably more like 3000 PSI. If the pressure is low I think it could be the relief valve that is located inside the pump but a more likely cause would the coupler, I think! If the splines are bad on the coupler it would still have some pressure to raise the boom, remember my charge light does come on for this, but not enough to drive the wheels. Would it not take more pressure to drive the wheels than raise the boom? The intermitant grab that I get from time to time would be the splines just lineing up right enough to catch and then once it spins they lose connection and I lose power. Does this make any sense or I am just dreaming up fixes?

 

[Tazza]

Robmints....No worries my friend you did not come across as being a jerk, just having some fun. The fact that I can run one side really rules out anything to do with dirty fluid, etc. I did also check last night for another resvervoir and there is not one. The only two that it ahs are tha chain case reservoirs. I am kind of shocked at some of the comments becasue my understanding was that this machine was pretty much state of the art when it was built in 92. But it sounds like some of the technology, like not having a reservoir seperate from the chain case, is old technology. This machine has been a solid machine for me and I abuse the hell the out of it. I pulled the seat last night to check out the pumps. The unit has a gear pump towards the front, a RH drive pump behind it and the LH drive pump behind it. The LH drive pump (the one in question) has a T fitting off of the top of it. I am looking for a set of high pressure gauges to see what the pressure is. I don't know what it should be ready but my guess is at least 2500 PSI and probably more like 3000 PSI. If the pressure is low I think it could be the relief valve that is located inside the pump but a more likely cause would the coupler, I think! If the splines are bad on the coupler it would still have some pressure to raise the boom, remember my charge light does come on for this, but not enough to drive the wheels. Would it not take more pressure to drive the wheels than raise the boom? The intermitant grab that I get from time to time would be the splines just lineing up right enough to catch and then once it spins they lose connection and I lose power. Does this make any sense or I am just dreaming up fixes?

That *T* fitting you see is probably your charge pressure port, it will have around 100PSI behind it, no more. Your high pressure lines are the 2 from each pump to the motors, these will get to around 5,000 PSI.
If your coupling is bad between the motor and any pump sections don't forget all sections after that will be bad. Like between the 2 left and right sections, if there was a problem there you youd have no hydraulics as the gear pump is the last in the line.
You have a point about the relief valves for the pump sections. I just don't know where they are located, but it will be behind what looks like a plug. If possible, try and swap motors then you will know its not a motor. Then if its found to be the pump, you can pull the relief valves and replenishing valves one at a time and clean. Hopefully that will solve the problem. If not, the inside of the pumps are quite simple, you should be able to get it going easily enough.

 

[92LX555]

That *T* fitting you see is probably your charge pressure port, it will have around 100PSI behind it, no more. Your high pressure lines are the 2 from each pump to the motors, these will get to around 5,000 PSI.
If your coupling is bad between the motor and any pump sections don't forget all sections after that will be bad. Like between the 2 left and right sections, if there was a problem there you youd have no hydraulics as the gear pump is the last in the line.
You have a point about the relief valves for the pump sections. I just don't know where they are located, but it will be behind what looks like a plug. If possible, try and swap motors then you will know its not a motor. Then if its found to be the pump, you can pull the relief valves and replenishing valves one at a time and clean. Hopefully that will solve the problem. If not, the inside of the pumps are quite simple, you should be able to get it going easily enough.

The way a mechanic at the New dealer that I contacted explained to me is that if the external coupler between the motor and the last pump (the LH pump) is bad then your senario would hold true. But apparently there is an interal coupler that would prevent the LH pump from working but would still allow the RH pump and the gear pump to work. It would be a reduced pressure which is why he theorized the charge light was coming on when raising the boom. As for the relief valve, it is supposed to be located within the pumps. The only relief valave that is external to the pumps is for the boom. Again, this is what I have been told. As for swapping the motors.....that is what most people say to do and it makes sens to swap them but to be honest, I don't want to have to do that. It sounds like way to much work when I it sound like some pressure guages on the LH pump should be able to tell me if the pump is bad. I will keep everybody posted but I can promise you, because I own the machine, no solution is a quick fix.

 

[Tazza]

The way a mechanic at the New dealer that I contacted explained to me is that if the external coupler between the motor and the last pump (the LH pump) is bad then your senario would hold true. But apparently there is an interal coupler that would prevent the LH pump from working but would still allow the RH pump and the gear pump to work. It would be a reduced pressure which is why he theorized the charge light was coming on when raising the boom. As for the relief valve, it is supposed to be located within the pumps. The only relief valave that is external to the pumps is for the boom. Again, this is what I have been told. As for swapping the motors.....that is what most people say to do and it makes sens to swap them but to be honest, I don't want to have to do that. It sounds like way to much work when I it sound like some pressure guages on the LH pump should be able to tell me if the pump is bad. I will keep everybody posted but I can promise you, because I own the machine, no solution is a quick fix.

I only have experience with 2 hydrostatic pumps so i could be wrong. Both were essentially the same setup but different brands. The way it runs is from the engine to the first pump section, no couplings here, then a coupling to the second section then another one to the hydraulic pump. The rotating groups have internal splines cut for the shaft to engage. Seriously, to damage these you would probably break the shaft first! I'm not saying that what you have been told isn't true, but from what experience i have, i would seriously doubt you have a coupling that is slipping inside the rotating group and allowing the other 2 sections to operate normally.
As for the relief, i honestly doubt it is internal. You will find the pump is a third party one, for example Vickers or sun-strand. They make these pumps to be versatile, you can change relief springs to alter pressures, no one in their right mind would make them internal if they wanted to be able to sell them easily. Look around the pump where the high pressure hoses are that feed the motors. You should find alan head bolts or hex head bolts around here. One of them on each side should be your relief, and you will have replenishing valves too. Have a look and pull each one one at a time and clean them.
Are you able to take any pictures? or can you see a pump model number?
If you look at my post on 751 rebuild in the general repairs section this is what you can expect to be in your pump.

 

[skidsteer.ca]

I only have experience with 2 hydrostatic pumps so i could be wrong. Both were essentially the same setup but different brands. The way it runs is from the engine to the first pump section, no couplings here, then a coupling to the second section then another one to the hydraulic pump. The rotating groups have internal splines cut for the shaft to engage. Seriously, to damage these you would probably break the shaft first! I'm not saying that what you have been told isn't true, but from what experience i have, i would seriously doubt you have a coupling that is slipping inside the rotating group and allowing the other 2 sections to operate normally.
As for the relief, i honestly doubt it is internal. You will find the pump is a third party one, for example Vickers or sun-strand. They make these pumps to be versatile, you can change relief springs to alter pressures, no one in their right mind would make them internal if they wanted to be able to sell them easily. Look around the pump where the high pressure hoses are that feed the motors. You should find alan head bolts or hex head bolts around here. One of them on each side should be your relief, and you will have replenishing valves too. Have a look and pull each one one at a time and clean them.
Are you able to take any pictures? or can you see a pump model number?
If you look at my post on 751 rebuild in the general repairs section this is what you can expect to be in your pump.

Just a note, but the pressure in your wheel drive circuit won't be high unless the wheels are having a hard time turning, or the harder you push, the higher the pressure until the relief opens.
Ken

 

[92LX555]

Just a note, but the pressure in your wheel drive circuit won't be high unless the wheels are having a hard time turning, or the harder you push, the higher the pressure until the relief opens.
Ken

The refief valve for the pumps is internal. They are not repariarable and when they go bad you must either rebuild the pump or buy a new one. At least this is what I am being told. Related to the relief valve it could be the spring. I plan on swapping the springs on the LH and RH pumps tonight and see if that makes a difference. If is clogged I should be able to tell that by swapping the springs as well. It looks like best case is a new spring or a clog, worst case a re-built pump. To bad you can not just put a new valve in it but because it is metal on metal you must rebuild it. I will try to take pictures tonight as well.

 

[92LX555]

The refief valve for the pumps is internal. They are not repariarable and when they go bad you must either rebuild the pump or buy a new one. At least this is what I am being told. Related to the relief valve it could be the spring. I plan on swapping the springs on the LH and RH pumps tonight and see if that makes a difference. If is clogged I should be able to tell that by swapping the springs as well. It looks like best case is a new spring or a clog, worst case a re-built pump. To bad you can not just put a new valve in it but because it is metal on metal you must rebuild it. I will try to take pictures tonight as well.

I have confirmed that the relief valve is internal to the pump and is the likely cause for the loss of propulsion in forward motion. I am hopeful that I will get away with a broken spring or maybe a worn spring or bad o-ring. New Holland does not sell just the valve and you have to buy the kit which inlcudes all of the items that I have circled. The price.....$480. Can you beleive that. I think I can have the pump rebuilt for under $300! Oh hell....I can not figure out how to attach the tif or jpg

 

[Earthwerks Unlimited]

My buddy's Lx665 used to make a lot of noise--until it blew a line from the pump to the motor. Meanwhile, it was spewing oil in the belly pan before anyone noticed it. I replaced the hose and topped off the fluid and was fine. The fluid reservoir supplies both separate piston drive pumps and motors, and it supplies the accessory drive pump which is a gear pump. The drive systems and the accessory system are not connected hydraulically; you could lose one or both systems without affecting one or both. I have a hunch that since the charge light comes on, the itty bitty charge pump may have broke--it supplies a lower PSI to the pump to keep pressure on the small pistons to keep them in contact with the swash plate inside. You may just luck out and have to replace just the charge pump. When I had the hydro system in my midsize backhoe go out which uses a similar size pump and motor, the rebuilder warned me that if he only tested and rebuilt one pump or motor, he would not honor the warranty--a sort of "Got cha". So I had him rebuild both for a little over a grand (for a pump and motor). BTW, the chain case reservoirs do not hold any fluid for the hydraulic system--if you DO find an excess amount in there that means the seal of the motor has blown and dumping fluid in the chain case.

 

[92LX555]

My buddy's Lx665 used to make a lot of noise--until it blew a line from the pump to the motor. Meanwhile, it was spewing oil in the belly pan before anyone noticed it. I replaced the hose and topped off the fluid and was fine. The fluid reservoir supplies both separate piston drive pumps and motors, and it supplies the accessory drive pump which is a gear pump. The drive systems and the accessory system are not connected hydraulically; you could lose one or both systems without affecting one or both. I have a hunch that since the charge light comes on, the itty bitty charge pump may have broke--it supplies a lower PSI to the pump to keep pressure on the small pistons to keep them in contact with the swash plate inside. You may just luck out and have to replace just the charge pump. When I had the hydro system in my midsize backhoe go out which uses a similar size pump and motor, the rebuilder warned me that if he only tested and rebuilt one pump or motor, he would not honor the warranty--a sort of "Got cha". So I had him rebuild both for a little over a grand (for a pump and motor). BTW, the chain case reservoirs do not hold any fluid for the hydraulic system--if you DO find an excess amount in there that means the seal of the motor has blown and dumping fluid in the chain case.

Where can I find the charge pump at? I changed one of the two filters last night and it seemed to be better. I bought the other (the larger) filter today and will change that and the fluid tonight and see what happens. I am really trying to do everything I can to avoid having to re-build anything or tear anything apart. The chain case reservoir on the LX555 does hold hydraulic fluid. It is the ONLY reservoir in the system. Total capacity for this unit is 17 gallons. The LX665 may be different.

 

[robmints]

Where can I find the charge pump at? I changed one of the two filters last night and it seemed to be better. I bought the other (the larger) filter today and will change that and the fluid tonight and see what happens. I am really trying to do everything I can to avoid having to re-build anything or tear anything apart. The chain case reservoir on the LX555 does hold hydraulic fluid. It is the ONLY reservoir in the system. Total capacity for this unit is 17 gallons. The LX665 may be different.

Pictures would be neat 92. Here is a how to:http://www.skidsteerforum.com/DesktopDefault.aspx?tabid=54&frmView=ShowPost&PostID=2445
If you want you can send me the pics or links to pics and I'll put them up. [email protected]

 

[Earthwerks Unlimited]

My bad about the reservoir thing. I started thinking (uh-oh) about the 1987 L555 I had 6 years ago. It had a metal structure or tube that the oil flowed from one chain case to the other welded to the floor. Mine had some hydraulic issues too as I recall. I do remember a metal, tubular-type strainer that screwed into a vertical tube on what would be the right side (operator position). Mine was clogged with black grit, rust (from the chain cases) and what looked like algae and thick, gooy snot. I cleaned it with gas, then carb cleaner, then soap and water. Reinstalled it and it worked great. The filter/strainer is quite expensive as I recall which is why I cleaned mine (I think it's brass mesh if memory serves)

 

[92LX555]

My bad about the reservoir thing. I started thinking (uh-oh) about the 1987 L555 I had 6 years ago. It had a metal structure or tube that the oil flowed from one chain case to the other welded to the floor. Mine had some hydraulic issues too as I recall. I do remember a metal, tubular-type strainer that screwed into a vertical tube on what would be the right side (operator position). Mine was clogged with black grit, rust (from the chain cases) and what looked like algae and thick, gooy snot. I cleaned it with gas, then carb cleaner, then soap and water. Reinstalled it and it worked great. The filter/strainer is quite expensive as I recall which is why I cleaned mine (I think it's brass mesh if memory serves)

Ok so I now that I working on this thing very slowly but things have been crazy busy. The unti still is not fixed and I have been borrowing my dairy farming friends Bobcat to move manure when I need to. The LH drive pump has been pulled and sent to a local hydraulic repair shop. They looked at it and found nothing wrong but a worn swash plate.....and even at that not even to effect the performance. So it took a couple of more weeks to pull the LH drive motor. It is now at the shop to be looked at as well. My question is if it is not the motor or the pump, where do I go from there? I have cleaned the metal inlet filter, changed the two filters, and will drain the remainder of the fluid and put clean fluid in. Could it really have been dirty fluid or water in the system? If so, why would I only lose the drive on one side?

 

[Tazza]

Ok so I now that I working on this thing very slowly but things have been crazy busy. The unti still is not fixed and I have been borrowing my dairy farming friends Bobcat to move manure when I need to. The LH drive pump has been pulled and sent to a local hydraulic repair shop. They looked at it and found nothing wrong but a worn swash plate.....and even at that not even to effect the performance. So it took a couple of more weeks to pull the LH drive motor. It is now at the shop to be looked at as well. My question is if it is not the motor or the pump, where do I go from there? I have cleaned the metal inlet filter, changed the two filters, and will drain the remainder of the fluid and put clean fluid in. Could it really have been dirty fluid or water in the system? If so, why would I only lose the drive on one side?

It has to be the pump or motor, there is nothing left. Even slight wear on the swash plate can cause loss of power as the oil by-passes through the groove. I hope the checked the relief valve that is part of the pump too, thats the only other thing that can cause problems like this.

 

[mllud]

It has to be the pump or motor, there is nothing left. Even slight wear on the swash plate can cause loss of power as the oil by-passes through the groove. I hope the checked the relief valve that is part of the pump too, thats the only other thing that can cause problems like this.

I just got the repair manual that covers the hydrostatic system and steering system. In trouble shooting for/ When one side moves and the other side does not.
Relief valve stuck open; check and repair
Internal pump or motor damage: Check pump/case drain flow.
Brake engaged on one side: Check parking brake system and repair.
Gearbox Damage: Check and Repair.
Broken drive chain: Check and repair.
Linkage Loose or Broken: Check and repair.
New holland brakes their repair manual into several books. This one cost 31$ and 11$ Fed Ex Shipping. This manual is for my lx865 It has the complete brakdown of the pumps /motorsServos/so on and so on. it also gives good discriptions of what to look for when you disasemble and reasemble.The information is very complete of the whole system. Im not trying to sell you on ordering a manual but if you intend to keep your loader Invest in one.The phone no. is 1-800-635-4913 They will need your model no. and may need your serial no. Mike