Another dumb hydraulic question.

So, my arms won't lift, and after pulling the inspection cover, I'm lost.
There is oil seeping out of the front of the ram on top, and the oil is gurgling around inside of the pump.
So, I looked at the pictures and read the chapter in the FO-4 manual, and I'm still lost.
Would I be further ahead just rebuilding the whole unit, or am I just overlooking something.

This is a 1944 2n, and the hydraulics worked fine until this spring.

48755.jpg


I don't know if these will show up.

48756.jpg
 
SLWagner73,If you see oil gurgling where you have the green arrow,The hydraulic relief valve is bad/leaking,stuck open/trash.Get one and replace it.
wml_8N638.jpg
 
See tip # 16 to check the pressure relief valve.

Oil leaking down from the hydraulic cylinder is a likely source of it not lifting too.

Post back when you are ready to pull the top cover & rebuild the lift cylinder.
75 Tips
 
And there in lies the question, do I order a safety valve, a pump kit, piston rings?
What should I start with in the parts department?
I plan to order the parts just as soon as I know what to get. Should I tear it down first? Or just order rebuild kits and misc. parts?
 
Before you start, it would be a wise move to get a jig from Zane Sherman (http://www.bramblett.com/zane/ ) to adjust the internal linkage. And, make a couple of ?guide studs? by cutting the heads off of two 7/16-14 x 3 5/8? bolts. Also, if your lift cylinder rebuild kit has the leather washer, get CNH part number 87051231 which is the neoprene washer for the lift piston instead of the leather one.

You can test the pressure relief valve and replace it if need be while the lift cover is off. Get all your parts here or from nnalert's.

The lift cover weighs nearly 100 lbs with the upper lift arms attached, & is very hard to maneuver. An engine hoist is an excellent idea. Remove the seat and spring, disconnect the upper lift arms at the knuckles. Remove the 14 bolts that hold the cover to the housing. (note that there are three different lengths) DO NOT remove the four nuts under the seat! Remove the right side inspection cover so you can remove the control rod tip from the pump intake valve. Lift the back of the cover straight up and slide a piece of wood under the cover to keep the tip of the control rod out of the rocker shaft. Once you are sure the control rod is out of the rocker shaft, you can then remove the cover. Turn the cover upside down, remove the four bolts that hold the cylinder to the cover, & use a little compressed air on the cyclinder to remove the piston. Check the cylinder for excessive scratches, hone if necessary. ( Or just replace the cylinder & don?t worry about honeing it out too much; that's what I always do ) Install a new piston with "0" ring and backing washer in the cylinder. Install the CNH neoprene washer w/ the concave side toward the ?O? ring. At this point, check the cam follower pin & the control rod. If the cam follower pin is worn replace it. Then, if you have a jig, adjust the linkage to specs. The ?shade tree? adjustment was to bend the control arm to compensate for normal wear in the linkage, springs & cam follower pin. If the control rod is bent, remove it & straighten it. (very carefully; they break easily!) Replace the gaskets under the cylinder and bolt it back on the cover. Put the gasket on the tractor (no sealer) and put the guide studs in place. Unless you do this every day or have eyeballs in your finger tips, get some help to guide the tip of the control arm back into the rocker shaft. (this is the point you will wish you had a engine hoist to hold the top cover while the control rod dances around the intake valve arm on the pump!) Align the cover holes up with the housing holes. Remove the guide studs. Tighten cover bolts, connect lift arms install the seat. Re-install the inspection covers with new gaskets.
75 Tips
 
(quoted from post at 21:32:16 05/10/17)
Don't hold me to it the jig is for a 8N with position control...
...and, oil movement in the middle of the pump is perfectly normal.....the scotch yoke simply stirs it.
 
I'm not contradicting you, Bruce, but why no sealer on the cover gasket? I thought you were supposed to seal it thoroughly with Permatex?
 
I should have thought that gasket cement would make the gasket LESS vulnerable to failure due to hydraulic pressure?

Why, even the lovely Rachel Gingell says so!

https://www.youtube.com/watch?v=XcWtNVOxzDg

(at about 11:25 into the video)
 
(quoted from post at 10:28:40 05/11/17) I should have thought that gasket cement would make the gasket LESS vulnerable to failure due to hydraulic pressure?

Why, even the lovely Rachel Gingell says so!

https://www.youtube.com/watch?v=XcWtNVOxzDg

(at about 11:25 into the video)

Gasket sealer or anything other than a dry gasket here, makes it slippery. As Bruce said it very well may then blow out where the tube transfers pressurized oil to the lift cover.

Zane's Jig while great for the 8N lift is not needed for the 9N / 2N.

Also as said some swirling of oil is normal as the turning pto shaft and the pump itself will cause this. Excessive oil movement would be oil blowing out through the relief valve.

If you see oil leaking down from above, this is most likely your problem. Rebuild the lift cover with a new style NAA piston & O-ring. Some like to rebuild with the original style piston and three steel rings if the cylinder is scored badly.
 
"Gasket sealer or anything other than a dry gasket here, makes it slippery. As Bruce said it very well may then blow out where the tube transfers pressurized oil to the lift cover."

Maybe I'm hopeless, but that makes no sense to me at all.
 

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