Still having Hydraulic Problems

RobBruno

Member
I am still having problems with the Hydraulics on my 8N. I posted before and got some advice and here is what I did.
Relief valve. Removed and cleaned. The valve still seems to function and work fine.
Removed and cleaned valved and springs. I removed each of the valve clamps and cleaned the valves, springs, plugs, and chambers. I did not remove the champers from the pump. When I did this, I found one of the valve guides was bent and one intake valve would jam on the guide. I straighten the guide as best I could and hte valve would move freely over the guide. I reassembled both sides of the pump keeping the correct valves in the chambers.
Honed the ram cylinder and replace the rings on the piston
Replaced the cam follower pin
Readjusted the linkage like described in several post.
Washed the entire sump area with mineral spirits
Intake and exhaust control valve move in and out freely.
I refilled the sump with the correct oil and tested. Without the cover, I started the tractor and engaged the pump. Using a long screwdrive, I moved the control valve to see if any oil would get pushed up to the top of the feeder tube and I got nothing. The pump yokes were working back and forth, but nothing at the top. No turbulance in the oil exempt from the PTO shaft spinning. No air bubbles or anthing coming to the top. Does any one have any suggestions for what next? Where else could there be a problem? Would completely removing the pump and disassamble be next? Any advice at this point would be grealy appreciated as far as what to look for next.
 
Did it ever work while you have owned the tractor? How long did it sit not working? If it sat a long time &/or had a lot of sludge in it, then the small holes & passages in & behind the intake & exhaust control valve bushings located near bottom of pump could have trash plugging them. Did you run it long enough to let fluid work the air out? Are you sure you pushed the intake control valve all the way until linkage touched the pump housing (full open intake)?
 
(quoted from post at 22:52:34 10/20/14) Did it ever work while you have owned the tractor? How long did it sit not working? If it sat a long time &/or had a lot of sludge in it, then the small holes & passages in & behind the intake & exhaust control valve bushings located near bottom of pump could have trash plugging them. Did you run it long enough to let fluid work the air out? Are you sure you pushed the intake control valve all the way until linkage touched the pump housing (full open intake)?
JMOR, Yes, the lift worked while I had the tractor. I have had the tractor for at least 15 yrs and my dad had it before that for at least 10 more. The hydraulics always work very well. I started to have to push down on the draft control for the lift to come up, but I figured that was because of the cam follower pin which I replaced. The lift stopped working this winter. The tractor maybe sat for a month or so and then when I went to take it out to plow snow, the lift would not work. It used to move very slow in the winter till the tractor warmed up and it worked fine. It has not worked since last winter. I can't say there was much sludge in the bottom but the oil was almost brown so I am sure there was plenty of water mixed in. I am pretty sure I pushed the control valve with the screwdriver all the way in. I worked it a couple times to see how far it would have to go before I put the oil in. Can you remove the control valves without removing the pump?
 

Brown oil (plenty of water in it) after sitting for a month will separate and the water goes to the bottom. Then it freezes (at least around here) and starts breaking stuff. In the midwest we commonly see 8N pump housings that freeze and break out the back wall of the pressure chamber between the the 2 valve sleeves. It won't pump anything when that happens. You cannot check out the pump without removing and disassembling it. If you want it to work this winter, give in and pull the pump and see what's wrong with it.
 

Oh 'ell. I can do that all by myself and not have it freeze!

Just a "little tapping on the pto shaft to re-engage after rebuild.






Some people are just plain dangerous with a hammer in their hand....guess I'm one of them. Got the pleasure of rebuilding another pump to install. :roll:
 
(quoted from post at 20:50:22 10/20/14)
Oh 'ell. I can do that all by myself and not have it freeze!

Just a "little tapping on the pto shaft to re-engage after rebuild.






Some people are just plain dangerous with a hammer in their hand....guess I'm one of them. Got the pleasure of rebuilding another pump to install. :roll:
ust a little love tap...with a 10# sledge?
 
I took John's advice and today dropped the pump. The PTO shaft came out with no problem as well as removing the pump. I started to pull the pump apart and everything looked in suprising good shape. The Intake and Exhaust control valves had no corrosion or gunk build up and seem to fit fine in the bushings. The relief valve which I had already removed and and cleaned was fine. Getting the valve chambers off was a bit of a challenge. They seemed glued to the main housing. Once they came off,the pump yokes, cam blocks, and cam came out with not problem and don't have any excessive wear or any kind of issues. I took about the valves out of the champers and this is where I found the only thing that I would say is unusaul. One side had no oil in it at all from when I tested it the other day. The other side had some oil in. I did remove the 4 pipe plugs and each side had a little water run out. Again one side, had some oil, but the other side looked almost dry. I cleaned the pump body with mineral spirits looking for cracks and didn't find any. Besides the water in in the valve chambers and basically no oil at all in one side, everything else looked in really good shape. The valve guide that I straigten allowed the valves to continue to slide. I am just wondering about the tolarence and if it gets jammed when there is pressure. My other question is with the relief valve. My functions in that the plunger goes in and out with out any problem. But, should it have a higher spring pressure? It sounds like a lot of people replace these. What normally goes wrong? Outside of cleaning all the passages with 2+2 and blowing a lot of air in the pump to clean it out, I am not sure what else to do. If I buy new valves and guides to rebuild the chambers, do I need to resurface the valve seats? Is there a way to test the pump once I put it back together before putting it back in the tractor to see if it works?
 
The item referred as "the relief" valve is actually two valves in one. A relief valve and a check valve. You may be aware of this, but many are not, so............
 
No easy way, unless you can rig up a way to apply 1600+ # pressure to it. John Smith, of course, has, but with out a machine shop & porta-power, most won't be able to do that.
 

I've pressure tested a lot of relief valves. If I pull 5 original relief valves from used pumps and test them, I might get one that works correctly - if I'm lucky. Of the other 4, I might get one that benefits from a new ball and spring. But not often. The seat gets damaged and there's no easy way to fix that. In my experience the vast majority of original relief valves are faulty and they cause the most hydraulic problems of any component in there. They're not that expensive, just assume it's bad and replace it.

The 4 valves in the chambers are the second most troublesome parts. The seats are normally pitted as well as the valves. If they don't seal, pump efficiency goes out the window.
 
(quoted from post at 13:01:50 10/21/14)
I've pressure tested a lot of relief valves. If I pull 5 original relief valves from used pumps and test them, I might get one that works correctly - if I'm lucky. Of the other 4, I might get one that benefits from a new ball and spring. But not often. The seat gets damaged and there's no easy way to fix that. In my experience the vast majority of original relief valves are faulty and they cause the most hydraulic problems of any component in there. They're not that expensive, just assume it's bad and replace it.

The 4 valves in the chambers are the second most troublesome parts. The seats are normally pitted as well as the valves. If they don't seal, pump efficiency goes out the window.

Any thoughts on a re-seating tool/procedure or is that simply new chambers as well? At $200+ that is beginning to get pricey....

TOH
 
(quoted from post at 19:40:44 10/21/14)

Any thoughts on a re-seating tool/procedure or is that simply new chambers as well? At $200+ that is beginning to get pricey....

TOH

There was a NuDay service tool available for that.

pumpseattool1.jpg


pumpseattool2.jpg


It always looked to me like one of those seat resurfacers that plumbers use on faucets that I could never get to work right. Always left chatter in the surface. And, what do you do when it gets dull? So, rather than look for one of those, I just made a simple mandrel to hold a stone. Actually, 2 stones as the one for the lower seat is a smaller diameter and is extended out further. Here's a picture with the upper seat stone installed. Don't have one with the lower stone installed, but you get the idea.

pumpseattool4.jpg


pumpseattool3.jpg


pumpseattool5.jpg


It's a running fit to the bore, so it doesn't wobble. A few turns by hand usually does the job, and I can diamond dress the stone(s) anytime they get worn. Not sure there would be a market for them. 99.9% of the guys would only need it one time.
The chambers need replaced if the seats are too badly pitted or if the piston bores exceed .803". I'd guess 3 out 4 originals are normally good enough to reuse with a little cleanup on the valve seats and some new valves, barring any other damage like cracks.
.
 
That tool looks like just what I need. Sounds like the original tool might be hard to find. I am going to try and clean mine, but I looked down in there with a flash light and I can see some pitting. The valves themselves look pretty good. Just hoping the thing will function with a new relief valve and good cleaning.
 
(quoted from post at 20:29:26 10/21/14) But how can I tell if mine is bad? Are there any signs that it is not working?

You can leak check them (valves) with air are vacuum...

Pump assembled You can hold the test port up and fill the hole with gas/varsoil/ mineral sprints with the control valve in it should hold the fluid with it out it should dump the fluid...
 

I preach driving those bushings out cuzz I had one that was stopped up in the pump housing at the bushing and all are full of trash to the point I can not believe they worked...
 
(quoted from post at 01:57:09 10/22/14)
I preach driving those bushings out cuzz I had one that was stopped up in the pump housing at the bushing and all are full of trash to the point I can not believe they worked...

Yes. The intake not so much, but the exhaust bushing has just 2 itty bitty holes and all the dirt and gunk build up around the bushing in the housing. Like you say, some are plugged up so bad it's amazing they work.
 
(quoted from post at 20:22:27 10/21/14)
(quoted from post at 19:40:44 10/21/14)

Any thoughts on a re-seating tool/procedure or is that simply new chambers as well? At $200+ that is beginning to get pricey....

TOH

There was a NuDay service tool available for that.

Yep - I had toyed with the idea of getting some made but I like your solution far better. As for market - $200 for new chambers or quite a bit less for a one use tool to resurface the old ones. I suspect they would prove to be right popular ;-)

TOH
 
(quoted from post at 04:22:27 10/22/14)
(quoted from post at 19:40:44 10/21/14)

Any thoughts on a re-seating tool/procedure or is that simply new chambers as well? At $200+ that is beginning to get pricey....

TOH

There was a NuDay service tool available for that.

pumpseattool1.jpg


pumpseattool2.jpg


It always looked to me like one of those seat resurfacers that plumbers use on faucets that I could never get to work right. Always left chatter in the surface. And, what do you do when it gets dull? So, rather than look for one of those, I just made a simple mandrel to hold a stone. Actually, 2 stones as the one for the lower seat is a smaller diameter and is extended out further. Here's a picture with the upper seat stone installed. Don't have one with the lower stone installed, but you get the idea.



It's a running fit to the bore, so it doesn't wobble. A few turns by hand usually does the job, and I can diamond dress the stone(s) anytime they get worn. Not sure there would be a market for them. 99.9% of the guys would only need it one time.
The chambers need replaced if the seats are too badly pitted or if the piston bores exceed .803". I'd guess 3 out 4 originals are normally good enough to reuse with a little cleanup on the valve seats and some new valves, barring any other damage like cracks.
.

I have cut them with a drill bit because that were rusted that bad then came back and dressed them the best I could with a stone it was hit and miss and never was happy with it... I do like your tool 8) I will look into it....
 

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