8N Hydraulic Issue

[east_tex]

Gentlemen:

I am continuing to try to get my grandfather's 8N in working condition again. There have been several issues with carburetor and ignition that seem to be resolved now. Currently the hydraulics are a problem. I attached a gauge to the 1/2 inch plug on the hydraulic pump plate and backed the tractor up to my pick up truck reciever hitch and lifted the 3 point. The truck rose slightly, not off of the ground but stretched the springs, and the gauge read 500 psi. The right side inspection plate was removed, there was only a slight drip coming from above, and no other visual turbulence. The oil is very heavy, must be at least 90 wt, and very dirty. I drained the oil and large chuncks of muck came out of the drain. I stuck my hand down in the inspection hole and there is at least an inch of muck on the bottom. What do I do now? If I put the 5 gallons of 134 oil already bought for $55 in the thing it seems that it will become very dirty very quickly. Should I go ahead and remove the pump and clean out the bottom. Should I also put a kit in the pump when I get it out? Or if I just clean everything and put in fresh oil is this possibly going to fix the problem? Also, will there be muck in the bottom which will dirty the new oil where the other two drain plugs are located? Any comments appreciated.

 

[Bob]

If it doesn't left with 90-WT oil, it sure ain't gonna lift with the UTF.

If the lift cylinder, lift cover gasket, or pump gasket aren't shooting a stream of oil, my next suspect would be the relief valve.

 

[john bray]

I would get a gallon or two of diesel fuel and run it thru the hydro to purge that sludge give it a good rinse. This will help clean out the valves for sure!

 

[Bruce (VA)]

That was a nice description of what you've done....but you left out on key part: just what is the problem?

I'll assume it won't lift. Correct?

You don't lose a thing by cleaning the pump. That might fix it, but finding (or at least describing) the problem would be a good place to start.

If the arms drop w/ the tractor off or the clutch depressed, chances are you have a worn lift cylinder or piston (or both), a blown top cover gasket or a leaky pressure relief valve. Take the inspection plate w/ the dipstick off. Lift a heavy implement & look inside w/ the tractor running & the PTO engaged to see if you notice oil running from the top cover. If oil is running steadily from the top cover the chances are the lift cylinder needs to be rebuilt. It’s less likely, but a possibility, that the top cover gasket is bad. (It’s very difficult to detect the exact source of the oil leaking inside of the top cover while looking through the inspection port). If no oil is running down from the top cover, look at the rear of the pump in the oil with the load still on it and see if you notice turbulence in the bottom. (Some movement of oil will be normal with the PTO shaft turning). You could have a weak pressure relief valve which will be detected by turbulence in the oil. To check for a slow leak, lift a heavy implement, turn the tractor off & put a ½ inch clear plastic hose on the end of the valve & stick the other end of the hose through the inspection port. With pressure in the pump, a bad valve will likely show some fluid in the hose.

Until you are sure of the problem, I wouldn't start buying parts.

There are two ways to clean the pump; the “quick clean” that gets a lot of the crud out of it, & the right way that gets all of it, including the hard packed crud in the pump base.

For the quick clean, after you get the old fluid drained out (overnight is best) remove both inspection plates & start pulling the sludge in the pump base out by hand. Then, get a couple of gallons of kerosene or diesel fuel & pour it into the pump base. Catch it in a bucket & reuse it. (Some folks use a hand garden sprayer.) Flush the pump base out 5 or 6 times. Do not start the engine to run the kerosene through the pump; kerosene and diesel fuel do not have sufficient lubrication properties for a 60 year old hydraulic pump designed to be immersed in 90w gear oil. Some folks say it’s ok to start the engine, engage the pump for a minute or two, then turn the engine off. Your call on that one.

This 'quick-clean' is not as effective as dropping the pump & doing a full job. But if the choice is between doing nothing & the quick clean, spray it out. It worked for me for 3 years on my 1951 N. If you have the time, drop the pump; that is the right way to do it. I’ve done it both ways & don’t plan on doing the quick clean again.

Do not attempt to do this w/o the I&T FO4 manual; the pump has a bunch of little parts that will go back together wrong if you do not have the manual to go by.

With all of the fluid drained out, block the front wheels & get the rear wheels up at least a foot. (you'll see why soon enough) Remove the 4 bolts holding the PTO shaft in & pull it to the rear & out of the tractor. Loosen all of the bolts. Remove all but the 4 corner bolts. Then, carefully remove them. If you are lucky, the pump will drop free (and dump a pint or so of hydraulic fluid down your sleeves). If not, wrestle it free. The pump has 'ears' that fit into the housing; wiggle it a bit & it will drop free. If you have the rear tires a foot or more off of the ground, you will have enough arm room to hold the pump & lower it at the same time. Once you get it out & on the bench, it comes apart easily & can be cleaned piece by piece. Blow out every passage w/ compressed air. Putting it back is harder than pulling it out because you have a gasket to worry about. (no sealer on the gasket) And, you will probably need a helper to guide the control rod into the pump rocker shaft unless you’ve done this 6 or 7 times before!

While you have the PTO shaft out, it would be a good time to replace the seal on it. It's got two spring clamps around it. Take your needle nose pliers & remove the one in the front. Then, hang the shaft & bearing housing in your vice & tap the butt end of the shaft; the bearing cap will come off (and the shaft will land on your foot). Then, remove the other spring clip from the other side of the seal. At this point, remember that you never bought a seal driver & go get a BF socket & drive the seal out. If you have the new style seal, the white side goes out. Put some grease on it.

Contrary to conventional wisdom, not a lot of water gets in the oil from the shifter boot. Of course, if it's bad, replace it, but you get water from the draft control spring & the dipstick. But, most water is just a byproduct of the heating/cooling cycle of the oil.
50 Tips

 

[TheOldHokie]

(quoted from post at 13:59:24 04/04/10) Gentlemen:

I am continuing to try to get my grandfather's 8N in working condition again. There have been several issues with carburetor and ignition that seem to be resolved now. Currently the hydraulics are a problem. I attached a gauge to the 1/2 inch plug on the hydraulic pump plate and backed the tractor up to my pick up truck reciever hitch and lifted the 3 point. The truck rose slightly, not off of the ground but stretched the springs, and the gauge read 500 psi. The right side inspection plate was removed, there was only a slight drip coming from above, and no other visual turbulence. The oil is very heavy, must be at least 90 wt, and very dirty. I drained the oil and large chuncks of muck came out of the drain. I stuck my hand down in the inspection hole and there is at least an inch of muck on the bottom. What do I do now? If I put the 5 gallons of 134 oil already bought for $55 in the thing it seems that it will become very dirty very quickly. Should I go ahead and remove the pump and clean out the bottom. Should I also put a kit in the pump when I get it out? Or if I just clean everything and put in fresh oil is this possibly going to fix the problem? Also, will there be muck in the bottom which will dirty the new oil where the other two drain plugs are located? Any comments appreciated.

Well done actually. Since there are no substantial leaks visible and you have no pressure the outlook is not good. You might be lucky and have a relief valve problem. Simple test for that - reach in through the inspection port and slip a piece of hose over the end of the valve and hang the other end in a bucket next to the tractor. Repeat your test and if the hose dumps fluid into the bucke the valve is defective. If not in all likely hood the pump is badly worn and doesn't make pressure.

Good luck,

TOH

 

[Kenster]

Definitely go ahead and get it cleaned out as best you can. You don't really say what the problem is but you might get some improvement with just a good cleaning and new fluid. However, as a fellow Texan (near Houston) I found that 134D fluid is just too thin for the heat we have. I used it once because TSC was out of 90wt. I immediately had fast leak downs and leaks and seepage from virtually every seal and orifice. I drained the 134D and replaced it with 90wt and positive results were immediate.