NAA losing prime and air bubbles in the hydraulic fluid

[MarkWisconsin]

Hi, Another issue with the NAA Ive been working on for over 6 months. Wish I knew how to list photos to show the progress. Its coming along but as soon as I get one issue resolved I get another one. I got the hydraulics prime to go up before I painted it although I dont know how good because this tractor is new to me. It does have a vane pump which I removed along with the lines for painting. I also cleaned out the hydraulic sump with diesel fuel. Put everything back together and added fresh universal hydraulic fluid. Finally got it primed by putting air in the the dip stick hole. However next time I tried it I loss prime again. Air bubbles are in the hydraulic oil after I get it primed and runs a while. Then after it sits overnight the hydraulic oil clears up. Does a weak pump produce all the air bubbles or do I have a leak where the pump is sucking air. Is that even possible. Can someone from the group give me some ideas. Thanks Much Mark

 

[pomester]

Hi, Another issue with the NAA Ive been working on for over 6 months. Wish I knew how to list photos to show the progress. Its coming along but as soon as I get one issue resolved I get another one. I got the hydraulics prime to go up before I painted it although I dont know how good because this tractor is new to me. It does have a vane pump which I removed along with the lines for painting. I also cleaned out the hydraulic sump with diesel fuel. Put everything back together and added fresh universal hydraulic fluid. Finally got it primed by putting air in the the dip stick hole. However next time I tried it I loss prime again. Air bubbles are in the hydraulic oil after I get it primed and runs a while. Then after it sits overnight the hydraulic oil clears up. Does a weak pump produce all the air bubbles or do I have a leak where the pump is sucking air. Is that even possible. Can someone from the group give me some ideas. Thanks Much Mark

With a piston pump I would suspect the input shaft seal to have deteriorated allowing prime to be lost when the tractor sets. I'm not sure about the vane pump design and whether it could be susceptible to the same type of failure. Something like that is probably your best case scenario as much of the vane pump is not serviceable. Look for a leak associated with the suction side. Possibly the tube where it passes thru the transmission?

 

[MarkWisconsin]

Thanks pomester. Fortunately on a NAA/Jubilee the tubes from the hydraulic pump to the hydraulic sump are exposed and dont go through the transmission. Im thinking of scrounging up a piston pump and the appropriate lines and give that a try.

 

[Jim L WA]

Thanks pomester. Fortunately on a NAA/Jubilee the tubes from the hydraulic pump to the hydraulic sump are exposed and dont go through the transmission. Im thinking of scrounging up a piston pump and the appropriate lines and give that a try.

That's a lot of work. I would be inclined to find the problem with your vane pump. Do you have a shop manual for your NAA? There is some good information in there for pump loosing prime. When you put the pump and tubes back on after painting, did you use new O rings?

 

[showcrop]

Did you use new O-rings where the tubes attach?

 

[MarkWisconsin]

Jim and showcrop, Thank you for helping. Yes I did use O-rings. Why do you ask? Maybe I should have used Quad rings? I looked for a source for the proper rings for the tube connection for NAA/Jubilee which are different than the piston pump lines but couldnt find a source. I do have an IT manual which I have studied where it has a paragraph on "pump losing prime". Also want to add I did install a different Vane pump. After priming the arms came up just like old pump and lost the prime again after a 30 minutes of sitting. Mark

 

[Andy Wickiser]

Jim and showcrop, Thank you for helping. Yes I did use O-rings. Why do you ask? Maybe I should have used Quad rings? I looked for a source for the proper rings for the tube connection for NAA/Jubilee which are different than the piston pump lines but couldnt find a source. I do have an IT manual which I have studied where it has a paragraph on "pump losing prime". Also want to add I did install a different Vane pump. After priming the arms came up just like old pump and lost the prime again after a 30 minutes of sitting. Mark

Quite a while ago there was someone on this board with the same symptoms. He had replaced the suction line with a new one. After a lot of frustration he finally discovered a porous weld and tigged it to fix the problem. I guess the moral of the story is to carefully check the suction tube for pinhole leaks etc.

 

[MarkWisconsin]

Thank you Andy. Thats another angle I'll look into. Because everything is freshly painted I've been reluctant to remove the lift cover. However Im running out of other options. I actually put in a replacement lift tube because when I removed the cover previously to put in new piston orings and leathers I discovered the lift tube was bent pretty severely. There is a rubber grommet between the lift tube valve and where it connect into the cylinder assembly. I also thought that maybe the grommet is not in the proper position from when I put it back together resulting in the same symptoms as the leaky pickup tube you refer to in your post. I'll check out the lift tube situation next. Mark

 

[showcrop]

I asked because I know that on the XX0s andXX1s that the O-rings can be a problem and it is often recommended to go get the OEM rings from CNH. I don't know if the jube is the same but the XX0s let the oil out of the hydraulic sump through a hole in the front right of the chamber. There is really no where for air to enter except at the tubing or the ends. So either a porous weld or O-ring or a flaw would have to be the culprit.

 

[MarkWisconsin]

showcrop Thank you, I understand. I will get the correct orings. If I had a leaks at any of the Jubilee hydraulic line ends where thy make their connections with O rings would it show up in the form of hydraulic dripping on the floor or could it be just sucking air and no fluid leak.

 

[Btzj02]

showcrop Thank you, I understand. I will get the correct orings. If I had a leaks at any of the Jubilee hydraulic line ends where thy make their connections with O rings would it show up in the form of hydraulic dripping on the floor or could it be just sucking air and no fluid leak.

I would think that if the bad O ring is on the suction tube and above the normal hydraulic fluid level you may not see an external oil leak. If the bad O ring is below the normal hydraulic fluid level I would think you would see oil leaking after it has sit for a while.

 

[MarkWisconsin]

Ok Thank You Btzj02. After I get it back together I'll watch for oil leaks. Now just waiting on New Holland for parts.