NH air in hydraulic lines

[HCb]

Also, when you backblade or leave the machine parked where there is force pushing the rod in, you could be sucking air in past the rod seals. These seals do a great job of keeping fluid in, but are not made to keep air out. If you have air in the fluid, which all hydraulics do, after sitting, the air separates from the oil and causes a little air pocket. This is common in almost all machines, new included. I have been asked by dealers why their new machines do exactly what you describe and the 2 scenarios I described is all I could come up with. But honestly, I never really researched it too much. Not really a problem, just a weird occurence.

Andy

Thank you for your reply. I have encountered this problem in the middle of using the equipment, sometimes for hours of moving dirt without backblading. I just posted back with some observations I made today and I feel I have a better understanding of when the problem occurs. Since the problem has evidenced itself after the equipment has been in use for sometime, and without backblading, I think it may be something more like the vacuum that the dealership told me about. I just didn't believe what they were saying because it didn't make sense to me. Now that I understand the system a little better (from my time here) and have played with it to test some theories, I feel they may be right. I'll play with it some more and then see where I am.

--HC

 

[jinman]

Hello HCb, welcome to TBN and welcome neighbor. I'm just down the road south of Sunset. I have a TC45D I bought in Feb. 2001 and lots of loader work with my 16LA. I've done so much work that my pins are starting to wear to the point that I get several inches of movement at the bucket lip just due to wear/slop in the joints. I have never witnessed my curl cylinders actually retracting when backdragging, but I could not swear they don't do it some.

I really have not noticed any problem with exerting downpressure with the bucket lip enough to pop the front wheels right off the ground. From your description, I think I'd put the bucket into a backdrag position and then pop the hose off the QD for the extend side pressure and see if the bucket moves the cylinders. Having the QD off would isolate the bucket cylinder from the joystick valve and show for sure if there was air in the lines or if you had an internal cylinder seal leaking. I also have a pressure gage that I can rig to check internal pressures, but I don't have it currently rigged with a "T" so I can easily put it into the loader QDs. That would be something you could do to be able to actually see what pressures are being exerted in your loader hydraulics. Also, I haven't seen it mentioned, but the best loader response is always with the engine above 2000 rpm.

I'm retired and I'm close, so I'd be willing to help you look for problems if they continue to plague you. I have a full set of repair manuals for our tractors. Driving all the way to Decatur to haul a tractor in for service is a pain. I've not done that since my 50-hour service, but I've had a lot of help from Glen, the service manager at McMaster NH.

Finally, if you have specific problems related to your New Holland, you might find more detailed responses in the New Holland Owning/Operating section of this site. This is not to say that you have not received excellent responses here, but only to say that there are many specific problems that may come up where the answer is obvious to other NH owners, but your post may not be seen by them in the general forums area.

BTW: My neighbor owns a TC35A and used to work for McMaster. He's pretty knowlegeable too, but a very busy guy. Give me a shout in these forums or a PM if I can help.

 

[J_J]

Since HCb said he also has air in the BH, I think that the pump is sucking air from a leak, or cavitating and the air impregnated fluid is flowing through out the hyd circuits. and collecting in the cylinders. He also said that when the cyl are level, the air goes away, which is normal. To check this, take off the hose to the cylinder and run the hose to clean bucket, Activate the lever to put hyd fluid in the bucket. Check for air bubbles. If you can, look in the reservoir with a strong light and look for bubbles.

 

[jinman]

I had the opportunity to check out a couple of things on my TC45D with 1560 hours today. I raised the engine rpm to 2000 and then dumped the bucket in full regen position. The bucket went down and all the way to the stop, BAM!, without hesitation. I dropped the bucket down with the toothbar buried and pulled to backdrag. The cylinder rams did not budge. There's a bit of slack in the worn pins, but the cylinders were tight and unmoving.

On the bottom of your tractor under the right-side operator's platform is a rubber boot in the pump intake line from the reservoir. I think you need to make sure the hoseclamps are tight or that this rubber part does not have a small hole in it allowing air into your system. Check for air as J.J. suggested and also make sure this fitting is good. You might find that the solution to your problem is a simple one. Several people have damaged this rubber fitting and/or bumped it with debris under the tractor. It could surely be the source of your problem.

 

[HCb]

Hello HCb, welcome to TBN and welcome neighbor. I'm just down the road south of Sunset. I have a TC45D I bought in Feb. 2001 and lots of loader work with my 16LA. I've done so much work that my pins are starting to wear to the point that I get several inches of movement at the bucket lip just due to wear/slop in the joints. I have never witnessed my curl cylinders actually retracting when backdragging, but I could not swear they don't do it some.

I really have not noticed any problem with exerting downpressure with the bucket lip enough to pop the front wheels right off the ground. From your description, I think I'd put the bucket into a backdrag position and then pop the hose off the QD for the extend side pressure and see if the bucket moves the cylinders. Having the QD off would isolate the bucket cylinder from the joystick valve and show for sure if there was air in the lines or if you had an internal cylinder seal leaking. I also have a pressure gage that I can rig to check internal pressures, but I don't have it currently rigged with a "T" so I can easily put it into the loader QDs. That would be something you could do to be able to actually see what pressures are being exerted in your loader hydraulics. Also, I haven't seen it mentioned, but the best loader response is always with the engine above 2000 rpm.

I'm retired and I'm close, so I'd be willing to help you look for problems if they continue to plague you. I have a full set of repair manuals for our tractors. Driving all the way to Decatur to haul a tractor in for service is a pain. I've not done that since my 50-hour service, but I've had a lot of help from Glen, the service manager at McMaster NH.

Finally, if you have specific problems related to your New Holland, you might find more detailed responses in the New Holland Owning/Operating section of this site. This is not to say that you have not received excellent responses here, but only to say that there are many specific problems that may come up where the answer is obvious to other NH owners, but your post may not be seen by them in the general forums area.

BTW: My neighbor owns a TC35A and used to work for McMaster. He's pretty knowlegeable too, but a very busy guy. Give me a shout in these forums or a PM if I can help.

Hello, Jinman. I'm sorry for the delay in replying; the holiday and some family health problems have occupied my time and my mind.

I cracked open the fitting on one of the bucket rollout (extend) sides and found air/void there (I did this before I read your suggestion of opening the QD unfortunately...that would have been cleaner). After continuing to play with the unit some when I was using it I consistently get that when I lower/extend the bucket lip at the first position, I get slop in the cylinders, but when I use the second position (fast dump) I do not. If I extend the cylinders very slowly I do not get the slop. This occurs whether the bucket is loaded or unloaded which still perplexes me; if the load was sucking a vacuum on the extend side I'd understand that, but I don't think there would be enough suction with it unloaded to cause the vacuum. Even more, when extending I thought it was under pressure on the extend side which would avoid vacuum. Regardless, it occurs that way; loaded, unloaded doesn't matter: first position fast gets the slop, slow does not. Second position seems to avoid the problem altogether. I'm adapting to deal with it but I still don't like not knowing why it's happening.

I have cycled the backhoe cylinders several times now and the slop seems to be gone, and I do not appear to ever have the slop in the boom cylinders so I think I was just seeing slop in the backhoe due to hooking and unhooking it without fully cycling the cylinders to clear any air from the lines (the backhoe has some leaks to it which might allow air in when it's at rest on the ground).

Thank you for the offer to come help, it is appreciated. You are more than welcome to come view the problem firsthand (it'd be nice if someone would confirm what I feel I've seen). I have a 16 foot utility trailer I have used to haul the tractor so I could come your way, too. I'll see if I can figure out PM or the equivalent on this site and send you contact information. Beer's on me.

I'll look through the NH O/O section, too.

Thank you for your time and information and, again, I apologize for the delay.

--HC

 

[HCb]

Since HCb said he also has air in the BH, I think that the pump is sucking air from a leak, or cavitating and the air impregnated fluid is flowing through out the hyd circuits. and collecting in the cylinders. He also said that when the cyl are level, the air goes away, which is normal. To check this, take off the hose to the cylinder and run the hose to clean bucket, Activate the lever to put hyd fluid in the bucket. Check for air bubbles. If you can, look in the reservoir with a strong light and look for bubbles.

Hello, JJ, thank you for the reply. I have made a couple of observations which seem to indicate that the problem is isolated to the bucket cylinders. I'm not certain, but I'm pretty sure. After cycling the backhoe cylinders the slop seems to have dissipated so I think that came from disconnecting and reconnecting it after it sat for a while (more than a month). Your suggestion of running fluid from the cylinders to a bucket to look for air bubbles sounds good and I'll try that if I don't find something sooner than later. I have looked in the reservoir but not with a very good light which, at your suggestion, I will try the next time I am using the tractor for a while (enough time to get it stirred up).

--HC

 

[HCb]

I had the opportunity to check out a couple of things on my TC45D with 1560 hours today. I raised the engine rpm to 2000 and then dumped the bucket in full regen position. The bucket went down and all the way to the stop, BAM!, without hesitation. I dropped the bucket down with the toothbar buried and pulled to backdrag. The cylinder rams did not budge. There's a bit of slack in the worn pins, but the cylinders were tight and unmoving.

On the bottom of your tractor under the right-side operator's platform is a rubber boot in the pump intake line from the reservoir. I think you need to make sure the hoseclamps are tight or that this rubber part does not have a small hole in it allowing air into your system. Check for air as J.J. suggested and also make sure this fitting is good. You might find that the solution to your problem is a simple one. Several people have damaged this rubber fitting and/or bumped it with debris under the tractor. It could surely be the source of your problem.

Hey, Jinman. I had checked this rubber section you mention (I'm fairly certain is the same one you speak of since it's the only one I see under the carriage of the tractor) early on (part of my 'no obvious damage' check). I do not see any holes or abrasions but, to be honest, I did not tug on it to see if it was loose. There is no evidence of a leak there but still I will check it by physically trying to wiggle/move it. I will also check the clamps.

--HC

 

[jinman]

HC thanks for the PM and your telephone contact info. You'll have to excuse me for being a wimp, but it's 16 degrees here this morning and I DO NOT function well at that temperature. The weather guessers on TV say that the temps will be back up to the 50s and 60s this weekend, so I'll try to give you a call. I'll rig my pressure gage the best I can and bring it along so we can do some actual pressure testing and look for air. This should not be a long process as I will or will not be able to find the problem easily. I'm also not sure I have the correct fittings to make up a QD "T" as needed, we'll see. . . If not, maybe I have enough fittings that we can open the bucket cylinder line and hard plumb in the at the short loop hoses going to the rear of the bucket cylinders. I even have a spare hose that might make this the easiest thing to do. Having some real pressure numbers will surely tell us something.

If you have other plans for this weekend, just let me know. We'll do this when it's convenient for you as long as it's not so cold that my old joints freeze.

 

[tommu56]

What are the chances the hoses for the lift (and float) and the bucket dump are reversed? if they were and you went to float the bucket would dump uncontrollable?

I would switch them to see if it is a hydraulic circuit problem just don't push handle to float

tom

 

[Jbrink64]

is the lift spongey, or springy? If not, assume no air in the system. Probably the bucket cylinders are rolling out too fast, causing a void in the cylinder. Are you using a NH control valve, remote valves, or someone elses valve? The NH loader valve has a regen feature. When you push the lever all the way to the right, there is a slight detent, that's regen. push past the detent, and you'll get the problem you're experiencing.