Hydraulic question

[wood butcher]

I bet this tractor was in a flood and that is the main reason the owner was getting rid of it. Everything about this thread reeks of flood damage. With water in the pump the pump could have been damaged by freezing. I think if I was you id just go ahead and replace that pump if you have a decent price on it. I would check over everything else with a fine tooth comb as well. Check the fuses and make sure they don't have any corrosion as well.

Maybe but I dont think so. I do agree with you on the pump...I'll probably just go get a new one. I was just getting it in my head to go back out there and work on it some more. It's been nice...in the high 60's and all the snow is gone. Got up this morning and its 26 degrees. Winter wont ever end.

 

[wood butcher]

Ok I just spent a few hours working on the beast. Here is what I did...

I took the pressure side line off the hydro pump then started the tractor.

Fluid came out but it didnt shoot out. I was able to stop the flow of fluid by covering the discharge hole on the pump with my thumb. Surely it shouldn't be THAT easy to completely stop the flow. I then put the line back on and went up to the control to see if I could loosen the lines there and get anything to come out. The pressure was about the same...maybe a little lower and I could stop the flow easily by plugging the line with my thumb.

Then I cut the old hydro filter apart to see what was inside...oodles and oodles of sludge covered the fins of the filter

and...wait for it...metal shavings in the bottom of the filter.

So...my guess is my pump gears have started to come apart or those are shavings off of a gear in the tractor somewhere.

Anyone have any thoughts?

 

[JC-jetro]

pump can be taken apart to check the gear and inside of the case non destructively if you're careful. Those pieces of the metal are unlikely to be from the pump gears due to it's geometry. Is that filter you HST filter? was it on the intake side (suction) side of the pump? if so it appeared the filter is doing what is supposed to do. You might still have more gunk upstream of the filter. certainly you do not want to get them in to you pump if it is not damaged yet. with the filter plugged as you explain you will not get much flow. The pressure is built against the spring in the relief device , in other words a free flow pump and no restriction you can not build pressure. Now playing, the "dutch boy" you should start building pressure. If you don't it might be restriction in suction or loss of close tolerance between pump gears the inside of the case (tired, old pump). I'd suggest the same test with a clean filter and if the flow would not get better then I'd open up the pump for a looksy.

JC,

 

[wood butcher]

pump can be taken apart to check the gear and inside of the case non destructively if you're careful. Those pieces of the metal are unlikely to be from the pump gears due to it's geometry. Is that filter you HST filter? was it on the intake side (suction) side of the pump? if so it appeared the filter is doing what is supposed to do. You might still have more gunk upstream of the filter. certainly you do not want to get them in to you pump if it is not damaged yet. with the filter plugged as you explain you will not get much flow. The pressure is built against the spring in the relief device , in other words a free flow pump and no restriction you can not build pressure. Now playing, the "dutch boy" you should start building pressure. If you don't it might be restriction in suction or loss of close tolerance between pump gears the inside of the case (tired, old pump). I'd suggest the same test with a clean filter and if the flow would not get better then I'd open up the pump for a looksy.

JC,

That filter was the one I removed before i changed the fluid and filter. Sorry, I should have clarified. Every place I opened, produced flowing, low pressure fluid. Either my filter is not correct and is causing the fluid to flow slower than it should or the pump is worn out. That's my two lines of thought. Tomorrow, Im planning on going to see the NH dealer & get a new Hydro filter. I'll put it in & see what happens. If I don't get anything I'll proceed with taking the pump off & looking it over. The filter in the pic is from the screw on type hydraulic filter. I just cut the case on it with a hacksaw so i could see what's going on inside the filter. It definitely was doing it's job as it was full of junk. What do you think Jetro? Am I going in the right direction?

 

[JC-jetro]

. The filter in the pic is from the screw on type hydraulic filter. I just cut the case on it with a hacksaw so i could see what's going on inside the filter. It definitely was doing it's job as it was full of junk. What do you think Jetro? Am I going in the right direction?

I think you are on the right path of diagnosing the problem. Low flow can be attributed to suction restriction, discharge restriction or too much play between pump gear and case. The tolerances between gears and the case is very tight. I have a link down below that shows inner operation of gear type positive displacement pump. You might like it. I think there is high liklihood that you might have the same crud from the diffy all the way to the filter. On mine , I took the drain bolt on the bottom of diffy and no hyd oil came out. I proceeded by taking a piece of stiff wire and bend a hook at the tip. I then shoved it up thru the drain hole in to diffy and when I pulled out there came what looked like a dead rat out of the bottom. if that crap get in to inlet piping then it can severally cause low oil flow. Low oil flow or partial blockage lead to pump cavitation that eventually will destroy the pump. If you take the pump off, take a dremmel tool or punch and mark stuff upon disassembly so to remove guess work putting back in exact same order. Take gradual pics as you can follow it later if you need to.

good luck and post your finding. If gear and case is not damaged then pump overhaul can be done cheaply. I'd make sure to clean all the crud on the intake side and try it before pump tear down.

JC,

Gear pump - Wikipedia, the free encyclopedia

 

[nealfris]

Didn't read all four pages but my question (unless I missed it and if I did, sorry) Did you run the problem by the NH dealer 50 yards down the street? Probably a wealth of information.

 

[wood butcher]

Didn't read all four pages but my question (unless I missed it and if I did, sorry) Did you run the problem by the NH dealer 50 yards down the street? Probably a wealth of information.

I plan on asking him today. I hate asking a mechanic for free advice though.

 

[wood butcher]

I think you are on the right path of diagnosing the problem. Low flow can be attributed to suction restriction, discharge restriction or too much play between pump gear and case. The tolerances between gears and the case is very tight. I have a link down below that shows inner operation of gear type positive displacement pump. You might like it. I think there is high liklihood that you might have the same crud from the diffy all the way to the filter. On mine , I took the drain bolt on the bottom of diffy and no hyd oil came out. I proceeded by taking a piece of stiff wire and bend a hook at the tip. I then shoved it up thru the drain hole in to diffy and when I pulled out there came what looked like a dead rat out of the bottom. if that crap get in to inlet piping then it can severally cause low oil flow. Low oil flow or partial blockage lead to pump cavitation that eventually will destroy the pump. If you take the pump off, take a dremmel tool or punch and mark stuff upon disassembly so to remove guess work putting back in exact same order. Take gradual pics as you can follow it later if you need to.

good luck and post your finding. If gear and case is not damaged then pump overhaul can be done cheaply. I'd make sure to clean all the crud on the intake side and try it before pump tear down.

JC,

Gear pump - Wikipedia, the free encyclopedia

Thanks for the link...very informative. I guess I'll pull the suction line off and see if it's full of crud then move on down to the diffy if the new filter doesnt do anything. I might see what the NH dealer has to say as well. I didnt know that stuff would gum up the way it did. My Deere was new when I bought it so I never had this kind of a problem.

 

[wood butcher]

Just went to the NH dealer & talked to them about it. The mechanic is out @ school today so I had to make due with the parts guy and some guy from the back who seemed to be semi-knowledgeable. They seem to think it's gunked up in one of the relief valves or something. I went ahead and bought a new filter ($43) and new shims for the one relief valve. I'll play with it tonight & let you guys know how it goes. They seemed to think there was a screen on the pickup line although the diagrams dont show one. Doubtful since the diagrams don't show one. Who knows. Getting really frustrated.

 

[JC-jetro]

Getting really frustrated.

Patience grasshopper as the kung Fu man says,


You might look at the pdf below. It lists out a bolt (item 24) on the spin on filter cartridge. Although they don't clearly say it it might be the relief he is talking about. it sure look like a banjo bolt that could also be plugged. It should be easy to remove and inspect. The main relive valve valve on hyd system is downstream of the pump so it can not effect the pump flow/pressure when the discharge pipe is removed as what you have done. Again I'd personally make sure I inspect all inlet pipes/fittings right up to the pump before pump tear down.

JC,