antfarmer2
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Never reuse orings
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L555 Please save me from divorce!
- Thread starter palmtree
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Are you saying to put on a new o-ring every time I take a hose off? I haven't been doing that. I didn't replace any of the o-rings where the hoses connect between the pumps and motors. I haven't noticed any oil leaks.Never reuse orings
antfarmer2
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If they are old replace them if new check them goodAre you saying to put on a new o-ring every time I take a hose off? I haven't been doing that. I didn't replace any of the o-rings where the hoses connect between the pumps and motors. I haven't noticed any oil leaks.
If you are talking about the expanded end of the suction fitting, that is there to keep the hose from blowing off. I hope you find your problem in that area, but I think it lies elsewhere. If the cap was not sealing or if you had an air leak on the suction side of the pump, the pump would never pick up prime since the oil level in the standpipe is below the pump suction hole of the standpipe.Are you saying to put on a new o-ring every time I take a hose off? I haven't been doing that. I didn't replace any of the o-rings where the hoses connect between the pumps and motors. I haven't noticed any oil leaks.
The nipple on the suction fitting has been damaged and has an indention about 1" long and maybe 1/8" deep along about half the length of it. Still seems like it would have sealed though -- but it is definitely damaged some. I've always wondered why the pump suction hole is above the oil level in the stand pipe. What you say about never priming makes since. Where do think my problem lies? When I performed the pump case drain flow test I used a clear vinyl tubing attached to the case drain. I could see the oil making it's way through the tube (slowly) and it was really foamy looking. It was also foamy in the bucket. Please let me know what you think it may be. thanks again, BrettIf you are talking about the expanded end of the suction fitting, that is there to keep the hose from blowing off. I hope you find your problem in that area, but I think it lies elsewhere. If the cap was not sealing or if you had an air leak on the suction side of the pump, the pump would never pick up prime since the oil level in the standpipe is below the pump suction hole of the standpipe.
The nipple on the suction fitting has been damaged and has an indention about 1" long and maybe 1/8" deep along about half the length of it. Still seems like it would have sealed though -- but it is definitely damaged some. I've always wondered why the pump suction hole is above the oil level in the stand pipe. What you say about never priming makes since. Where do think my problem lies? When I performed the pump case drain flow test I used a clear vinyl tubing attached to the case drain. I could see the oil making it's way through the tube (slowly) and it was really foamy looking. It was also foamy in the bucket. Please let me know what you think it may be. thanks again, Brett
The charge pressure sender is set to activate if the charge pressure is lower than 3.45 bar (50 psi). Normal charge pressure is approximately 11.03 bar (160 psi) as controlled by the charge check valve. The charge check valve is located in front of the large return line filter in the engine compartment.
Loss of forward and a harsh engagement of reverse on the same side of the machine is usually an indication of internal hydrostatic pump and / or motor damage on that side.
Loss of forward and a harsh engagement of reverse on the same side of the machine is usually an indication of internal hydrostatic pump and / or motor damage on that side.
- Check the charge pressure as stated in the service manual part number 40055510, page 4-11.
- Check the charge pressure drop as you stroke the left drive lever forward, and then back into reverse. Do not move a loader function as you do this.
Do this again but this time with the right drive lever.
With the oil at operating temperature the max pressure drop is 2.0 to 2.4 bar (30 to 35 psi). - If the charge pressure is low, remove the case drain line from the hydrostatic pumps and check the quantity of flow that is coming out of it, it should be approximately 3 gpm.
Beware:
If the hydrostatic pump has failed, the oil exiting from the case drain will be large in quantity and under a high pressure.
If the hydrostatic pump has failed, the oil exiting from the case drain will be large in quantity and under a high pressure.
Flow from this line should be no greater than about 3 gpm.
Move the left drive lever, if the flow is greater than 3 gpm and the charge pressure low warning lamp illuminates, the left side hydrostatic pump is damaged. If the pump is damaged, then most likely the left side motor bolted to the chain case is also damaged.
Carry out the above check using the right drive lever to check the right side hydrostatic pump.
Note:
A case drain test on the motors cannot be carried out as the motors are directly bolted to the chain case (hydraulic reservoir) and drain directly into the chain case.
If the charge pressure is low and there is not excessive flow when carrying out the above test, it indicates the hydrostatic motor is the problem.
Remove, disassemble and inspect the motor as detailed in the service manual (part number 40055510, page 5-1 thru 5-16).
A case drain test on the motors cannot be carried out as the motors are directly bolted to the chain case (hydraulic reservoir) and drain directly into the chain case.
If the charge pressure is low and there is not excessive flow when carrying out the above test, it indicates the hydrostatic motor is the problem.
Remove, disassemble and inspect the motor as detailed in the service manual (part number 40055510, page 5-1 thru 5-16).
Low hydrostatic charge pressure can be caused by either one, or a combination, of the following.The charge pressure sender is set to activate if the charge pressure is lower than 3.45 bar (50 psi). Normal charge pressure is approximately 11.03 bar (160 psi) as controlled by the charge check valve. The charge check valve is located in front of the large return line filter in the engine compartment.
Loss of forward and a harsh engagement of reverse on the same side of the machine is usually an indication of internal hydrostatic pump and / or motor damage on that side.
Check the charge pressure as stated in the service manual part number 40055510, page 4-11.
Check the charge pressure drop as you stroke the left drive lever forward, and then back into reverse. Do not move a loader function as you do this.
Do this again but this time with the right drive lever.
With the oil at operating temperature the max pressure drop is 2.0 to 2.4 bar (30 to 35 psi).
If the charge pressure is low, remove the case drain line from the hydrostatic pumps and check the quantity of flow that is coming out of it, it should be approximately 3 gpm.
Beware:
If the hydrostatic pump has failed, the oil exiting from the case drain will be large in quantity and under a high pressure.
Note:
A case drain test on the motors cannot be carried out as the motors are directly bolted to the chain case (hydraulic reservoir) and drain directly into the chain case.
If the charge pressure is low and there is not excessive flow when carrying out the above test, it indicates the hydrostatic motor is the problem.
Remove, disassemble and inspect the motor as detailed in the service manual (part number 40055510, page 5-1 thru 5-16).
- Worn main gear pump that powers the boom / bucket circuit.
- Wear in either the hydrostatic pumps or motors that results in too much case drain flow.
Return oil flow from the main gear pump boom / bucket cylinders is used to maintain this charge flow / pressure. When the boom or bucket cylinders are bypassed then oil going over the relief valve should be going back to the return / charge relief circuit.
Low / no charge pressure at bypass indicates the gear pump is worn and putting out little or no flow in the cylinder bypass condition.
Ensure that the flow and pressure at the gear pump meets specification at 53 lpm (14 gpm) at 2800 rpm, at 1000 psi (new pump).
Once gear pump flow is normal (may need a new pump), check for excessive case drain flow from the pumps. This should not exceed more than 13.2 to 15.0 lpm (3.5 to 4 gpm) at full engine speed, brakes locked, and the transmission engaged.
The above information if from NH. I would make sure you can clamp the hose to that fitting in an area that is not damaged. What they mean in the second post about going over relief is continue to hold the foot pedal in the activated position after the cylinders have reached the end of their stroke. This will cause the relief valve to open. If the charge pressure drops while the oil is going over relief than you may have a flow problem from the hydraulic pump..........When you said how much oil was coming out of the case drains I did not think that was enough........This is what I would do after you do the bypass test. Remove the hose going to the top of the hydro pumps and cap the end of the hose and hydro pump. Leave the fuel shut off so it can not start. Crank the engine and see if you can build the 160 psi in the charge circuit. After that I would reinstall the hose and start the engine and operate the hydros momentarily. I would then remove the hose again from the hydro pumps and attach a longer hose to it to reach a bucket. Cap the hydro pump again. This time start the engine and see how much flow you are getting out of the hose and if it is foamy. Only run the engine about 10 seconds.Low hydrostatic charge pressure can be caused by either one, or a combination, of the following.
Worn main gear pump that powers the boom / bucket circuit.
Wear in either the hydrostatic pumps or motors that results in too much case drain flow.
The hydrostatic charge pressure is set at 11 bar (160 psi) by the charge pressure relief valve located near the hydrostatic / hydraulic filters in the engine compartment. The low charge pressure warning light is set at 3.4 bar (50 psi) so charge pressure is below 3.4 bar ( 50 psi) when the light comes ON and freewheeling occurs.
Return oil flow from the main gear pump boom / bucket cylinders is used to maintain this charge flow / pressure. When the boom or bucket cylinders are bypassed then oil going over the relief valve should be going back to the return / charge relief circuit.
Low / no charge pressure at bypass indicates the gear pump is worn and putting out little or no flow in the cylinder bypass condition.
Ensure that the flow and pressure at the gear pump meets specification at 53 lpm (14 gpm) at 2800 rpm, at 1000 psi (new pump).
Once gear pump flow is normal (may need a new pump), check for excessive case drain flow from the pumps. This should not exceed more than 13.2 to 15.0 lpm (3.5 to 4 gpm) at full engine speed, brakes locked, and the transmission engaged.
OK Mike. Thanks again for helping me. I think I understand what I need to do. I will say that I too felt like I wasn't getting much fluid during the pump case drain flow test (but I assumed the less the better as far as pump condition). Now I see that you think my gear pump may be weak or something. I used a 9 foot clear vinyl hose for the case drain test. I didn't time it but I bet it took 20 seconds or so for the foamy looking fluid to make it's way thru that 9 foot x 1//2" hose before it ever even reached the bucket. Thus only about 1/2 gallon (maybe even less) or so after 3 minutes. Are all the fittings I'll need to cap standard SAE threads? I'll need to buy some plugs and caps and I don't want to get the wrong type thread. Can I just buy some of those plastic caps or do I need something stronger? Should I do all this with the loader on jack stands or can I do it with the tires on the ground. Also, I suppose if the gear pump is working properly I should get 14 gallons per minute out of that hose and that's why I should only run the machine for about 10 seconds? What does it mean if the flow from the charge pump is foamy?The above information if from NH. I would make sure you can clamp the hose to that fitting in an area that is not damaged. What they mean in the second post about going over relief is continue to hold the foot pedal in the activated position after the cylinders have reached the end of their stroke. This will cause the relief valve to open. If the charge pressure drops while the oil is going over relief than you may have a flow problem from the hydraulic pump..........When you said how much oil was coming out of the case drains I did not think that was enough........This is what I would do after you do the bypass test. Remove the hose going to the top of the hydro pumps and cap the end of the hose and hydro pump. Leave the fuel shut off so it can not start. Crank the engine and see if you can build the 160 psi in the charge circuit. After that I would reinstall the hose and start the engine and operate the hydros momentarily. I would then remove the hose again from the hydro pumps and attach a longer hose to it to reach a bucket. Cap the hydro pump again. This time start the engine and see how much flow you are getting out of the hose and if it is foamy. Only run the engine about 10 seconds.
When I check the flow in the charge cicuit will the fluid be coming out of the hose and into the bucket at 1000psi or just at charge pressure?The above information if from NH. I would make sure you can clamp the hose to that fitting in an area that is not damaged. What they mean in the second post about going over relief is continue to hold the foot pedal in the activated position after the cylinders have reached the end of their stroke. This will cause the relief valve to open. If the charge pressure drops while the oil is going over relief than you may have a flow problem from the hydraulic pump..........When you said how much oil was coming out of the case drains I did not think that was enough........This is what I would do after you do the bypass test. Remove the hose going to the top of the hydro pumps and cap the end of the hose and hydro pump. Leave the fuel shut off so it can not start. Crank the engine and see if you can build the 160 psi in the charge circuit. After that I would reinstall the hose and start the engine and operate the hydros momentarily. I would then remove the hose again from the hydro pumps and attach a longer hose to it to reach a bucket. Cap the hydro pump again. This time start the engine and see how much flow you are getting out of the hose and if it is foamy. Only run the engine about 10 seconds.
The plug you use for the hose must be a steel cap. I do not remember what size but they are what is known as JIC fittings. They are standard fine bolt thread so if you have any nuts you can estimate the size. I think they are 9/16......You should only have charge pressure at the hose when capped, but uncapped the pressure should be less coming out of the hose since you have removed all restrictions from the flow except for the friction of the oil running through the lines and cooler.... I was probably referring to the charge check valve and not the charge pump since the charge check valve removes the need for a charge pump.....The reason for running only ten seconds is to avoid damage to the hydro pumps since there will be no oil being supplied to them. You will probably tell immediately if you have much flow out of the hose so you only need to run for a few seconds.When I check the flow in the charge cicuit will the fluid be coming out of the hose and into the bucket at 1000psi or just at charge pressure?
There are three components the oil flow through before the hydro pumps. The control valve, oil cooler and the filter. If you are not getting flow I would be looking at the filter and filter mounting base first. Are you using OEM filters? This could explain the low flow but not the low charge pressure. If you have the check valve I would install it. Judging from the speed of the loader boom and bucket, I think you will find the hydraulic pump is not the problem, but check anyway.The plug you use for the hose must be a steel cap. I do not remember what size but they are what is known as JIC fittings. They are standard fine bolt thread so if you have any nuts you can estimate the size. I think they are 9/16......You should only have charge pressure at the hose when capped, but uncapped the pressure should be less coming out of the hose since you have removed all restrictions from the flow except for the friction of the oil running through the lines and cooler.... I was probably referring to the charge check valve and not the charge pump since the charge check valve removes the need for a charge pump.....The reason for running only ten seconds is to avoid damage to the hydro pumps since there will be no oil being supplied to them. You will probably tell immediately if you have much flow out of the hose so you only need to run for a few seconds.
OK. I should be able to get this done tomorrow. I just need to find a plug for the hose and since I'll be alone I'll need to install a long hose on the pressure gauge port and run the pressure gauge into the cab so I can see the charge pressure and run the controls at the same time. A hose that's good for 300psi or so should be enough to measure charge pressure (my gauge only goes to 300 psi anyway). Right? However, I will not be able to change the charge check valve tomorrow because I don't have the tools to remove it. I need a larger wrench for the valve and also an angled or crowsfoot wrench to remove the line behind it. As far as I can tell that is the only way to get the charge check valve out since it's hard plumbed in right before the filter mounting base. Do you know any tricks to removing the charge check valve? My manual acts like it's no big deal. Well I tried and failed once already so I think it's gonna be pretty tough job. I am using brand new OEM filters and when I changed them plenty of oil came pouring out of the base.There are three components the oil flow through before the hydro pumps. The control valve, oil cooler and the filter. If you are not getting flow I would be looking at the filter and filter mounting base first. Are you using OEM filters? This could explain the low flow but not the low charge pressure. If you have the check valve I would install it. Judging from the speed of the loader boom and bucket, I think you will find the hydraulic pump is not the problem, but check anyway.
I am reporting here as I move through things. That way I won't lose track of the pressure numbers. So I ran a hose and mounted a pressure gauge in the cab to monitor the charge pressure simultaneously while operating the machine. I reinstalled the gear pump and checked the oil level (it was full). When I first started the machine the pressure read just under 150 psi. I pulled it out of the garage and as it warmed up the pressure dropped to around 140 psi. I operated the boom a few times and moved the machine around in the driveway to warm it up and the charge pressure continued to inch down. It seemed to hang out around 120 psi or so. The pressure would drop a little as I raised the boom (no more than 10 psi) and then climb a little when I lowered the boom. When I brought the boom all the way up and went over relief the pressure only dropped around 1-2 psi. Not much drop at all. One thing I did notice is that it behaved much worse the more I drove around (especially turning) By the time I shut it down (maybe 15 minutes of running) it would barely turn at all and the charge pressure while sitting still was around 110-120 but as I stroked the levers the pressure would drop to well under 100 psi (maybe around 70 - 75 psi). I'm sure if I would have operated it much longer the charge light would have come on while attempting to turn. Now I need to run to town to pick the kids up and swing by NAPA to grab the correct plug to test the charge pressure with the hydrostat supply line dead-headed. After that I will also check the volume of flow from the charge line.The above information if from NH. I would make sure you can clamp the hose to that fitting in an area that is not damaged. What they mean in the second post about going over relief is continue to hold the foot pedal in the activated position after the cylinders have reached the end of their stroke. This will cause the relief valve to open. If the charge pressure drops while the oil is going over relief than you may have a flow problem from the hydraulic pump..........When you said how much oil was coming out of the case drains I did not think that was enough........This is what I would do after you do the bypass test. Remove the hose going to the top of the hydro pumps and cap the end of the hose and hydro pump. Leave the fuel shut off so it can not start. Crank the engine and see if you can build the 160 psi in the charge circuit. After that I would reinstall the hose and start the engine and operate the hydros momentarily. I would then remove the hose again from the hydro pumps and attach a longer hose to it to reach a bucket. Cap the hydro pump again. This time start the engine and see how much flow you are getting out of the hose and if it is foamy. Only run the engine about 10 seconds.
antfarmer2
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Oil still foamy? Hard to get pressure with bubblesI am reporting here as I move through things. That way I won't lose track of the pressure numbers. So I ran a hose and mounted a pressure gauge in the cab to monitor the charge pressure simultaneously while operating the machine. I reinstalled the gear pump and checked the oil level (it was full). When I first started the machine the pressure read just under 150 psi. I pulled it out of the garage and as it warmed up the pressure dropped to around 140 psi. I operated the boom a few times and moved the machine around in the driveway to warm it up and the charge pressure continued to inch down. It seemed to hang out around 120 psi or so. The pressure would drop a little as I raised the boom (no more than 10 psi) and then climb a little when I lowered the boom. When I brought the boom all the way up and went over relief the pressure only dropped around 1-2 psi. Not much drop at all. One thing I did notice is that it behaved much worse the more I drove around (especially turning) By the time I shut it down (maybe 15 minutes of running) it would barely turn at all and the charge pressure while sitting still was around 110-120 but as I stroked the levers the pressure would drop to well under 100 psi (maybe around 70 - 75 psi). I'm sure if I would have operated it much longer the charge light would have come on while attempting to turn. Now I need to run to town to pick the kids up and swing by NAPA to grab the correct plug to test the charge pressure with the hydrostat supply line dead-headed. After that I will also check the volume of flow from the charge line.
Well. It doesn't seem as foamy as when I ran the pump case drain flow test, but I can't see the oil as well now as I could then. So I'm not sure. I capped the line that supplies the hydrostatic pumps and cranked the engine without letting it start like Mike said to do. The pressure rose to 100 psi and stayed there. I couldn't find a fitting to attach the charge supply line to a hose in order to measure the flow from the charge line. Since the pressure was low when I tested it with the plugged line I decided to change the charge check valve (since I already bought a new one anyway). That was a major job with everything hard lined in like it is. After removing a bunch of stuff I managed to get the old valve out and putting the new one in was pretty easy. I was feeling pretty optimistic that this might solve my problems. Well, it is exactly like it was before. Charge pressure around 145-150 psi at start up slowly moving down to around 120 psi after driving around a little. Jerky and weak drive just like before. Well there goes another $120 and another day off wasted. I will try to round up the stuff needed to check the charge flow volume this weekend. Any other ideas? Thanks, BrettOil still foamy? Hard to get pressure with bubbles
I think we are at a point where we need to isolate the motors from the pumps. We have to determine whether we are not getting a supply of oil through the filter or which component is leaking internally. On the one hand the case drain was abnormally low suggesting low oil flow input to the pumps but the drop in charge pressure could also indicate a leak internally. If I had the machine in the shop I would remove the hoses from the motors and plug them. I would start the engine and watch the charge pressure and see if it is still low and if it drops as the oil warms up. If the charge pressure is still low I would then disconnect the case drain line again and attaché your hose to it. You can put the other end of the hose into the filler neck up front where the dipstick is. That way you are just recirculating the oil and it will allow you to pull the hose up enough to see how much flow is coming out. If the case drain flow is still low then I would suspect we have a supply problem through the filter. I can not remember if the charge pressure sender is before the filter or after. If the sender is before the filter then an obstruction in the filter head would not make the charge pressure drop. You can stoke the hydro levers slightly to build some internal pressure and see if this drops the charge pressure. Stroking the levers will cause the oil to bypass through the relief valves and that should increase the case drain.Well. It doesn't seem as foamy as when I ran the pump case drain flow test, but I can't see the oil as well now as I could then. So I'm not sure. I capped the line that supplies the hydrostatic pumps and cranked the engine without letting it start like Mike said to do. The pressure rose to 100 psi and stayed there. I couldn't find a fitting to attach the charge supply line to a hose in order to measure the flow from the charge line. Since the pressure was low when I tested it with the plugged line I decided to change the charge check valve (since I already bought a new one anyway). That was a major job with everything hard lined in like it is. After removing a bunch of stuff I managed to get the old valve out and putting the new one in was pretty easy. I was feeling pretty optimistic that this might solve my problems. Well, it is exactly like it was before. Charge pressure around 145-150 psi at start up slowly moving down to around 120 psi after driving around a little. Jerky and weak drive just like before. Well there goes another $120 and another day off wasted. I will try to round up the stuff needed to check the charge flow volume this weekend. Any other ideas? Thanks, Brett
What I don't understand is why I would only get 100 psi while cranking the engine (with fuel off) with the charge supply line plugged. Wouldn't that mean the problem is in the supply? Also why would the charge pressure be lower with the line plugged than it is when it is attached to the pumps?I think we are at a point where we need to isolate the motors from the pumps. We have to determine whether we are not getting a supply of oil through the filter or which component is leaking internally. On the one hand the case drain was abnormally low suggesting low oil flow input to the pumps but the drop in charge pressure could also indicate a leak internally. If I had the machine in the shop I would remove the hoses from the motors and plug them. I would start the engine and watch the charge pressure and see if it is still low and if it drops as the oil warms up. If the charge pressure is still low I would then disconnect the case drain line again and attaché your hose to it. You can put the other end of the hose into the filler neck up front where the dipstick is. That way you are just recirculating the oil and it will allow you to pull the hose up enough to see how much flow is coming out. If the case drain flow is still low then I would suspect we have a supply problem through the filter. I can not remember if the charge pressure sender is before the filter or after. If the sender is before the filter then an obstruction in the filter head would not make the charge pressure drop. You can stoke the hydro levers slightly to build some internal pressure and see if this drops the charge pressure. Stroking the levers will cause the oil to bypass through the relief valves and that should increase the case drain.
I would have thought it would also be more than 100 psi, but check valves and relief valves will "crack" before they fully open at their designated pressure, so it is possible there was just not enough flow when cranking. You could recap the line and momentarily start the engine to see if it changes. When the charge pressure drops does the boom and bucket also slow down? Unless there is something added to the loader which allows flow back to the chain cases, all the oil flow must either go through the check valve or the hydrostats.What I don't understand is why I would only get 100 psi while cranking the engine (with fuel off) with the charge supply line plugged. Wouldn't that mean the problem is in the supply? Also why would the charge pressure be lower with the line plugged than it is when it is attached to the pumps?
The boom is not noticeably slower when the charge pressure is lower. I know that 120 psi is lower than the 160 psi that this brand new charge check valve should keep it at, but from what I've read in other people's problems on this forum it sounds like the hydrostats should still work at that charge pressure. My machine won't work right even at start up when the charge pressure is 145-150 psi. I've read about people working their machine as normal until the charge light comes on and then even continuing for a while with the light on (and that means less than 50 psi). What does the control valve do besides distribute fluid to different circuits? Is there something in there that could restrict the flow to the hydrostatic circuit and cause this sort of problem? How about the oil cooler? Maybe it is partially plugged? Pressure in the oil cooler should only be charge pressure so couldn't I temporarily bypass it with a 300 psi hose? That should rule out a restriction in the oil cooler right? Also the charge pressure switch is immediately after the filter on this machine. It does seem to be leaking a little bit too. How would I go about inspecting the filter housing? Just remove that filter and look at it?I would have thought it would also be more than 100 psi, but check valves and relief valves will "crack" before they fully open at their designated pressure, so it is possible there was just not enough flow when cranking. You could recap the line and momentarily start the engine to see if it changes. When the charge pressure drops does the boom and bucket also slow down? Unless there is something added to the loader which allows flow back to the chain cases, all the oil flow must either go through the check valve or the hydrostats.
