Hydraulic Oil Leak

[Maj Dad]

Reference #16 on the 75 tips, I was running my 52 8N just to warm it up (can't stand to let engines/machinery just sit for extended periods), and lifted the box blade a couple of times, holding for a few seconds, just exercising it in general, and noticed a new oil leak from the top cover under the seat in front of the draft control lever. It leaks only when the lift is engaged, and while it isn't a high volume leak, it is a constant seep directly under the hump between the 2 front bolts. I am a former 8N user/owner (~50 and 30 years ago), I don't have any experience removing the top cover and getting into the hydraulics, and before I jump off the deep end, I am soliciting any suggestions as to course of actions before I begin at the end and wind up with a lawn ornament? The oil is very clean and relatively thin and doesn't look like 80-90 wt gear oil - could that be a factor? Need to get this fixed before 100 deg weather hits! Thanks in advance.
George J, Sumter, SC

"Lift a heavy implement & look inside with 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)."

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[Maj Dad]

I just got this in late January, so I don't go back a long way with it. No other problems to date.

 

[Bruce (VA)]

Tip # 16 refers to an internal leak, visible through the inspection port. You have an external leak which means a bad gasket.

You can pull the lift cover and just replace the gasket.

Or, you could adjust the linkage, rebuild the lift cylinder & replace the cam follower pin.

Your call. Here is how to do all of it:

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.

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 cylinder 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. ) 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

 

[Maj Dad]

Outstanding - thank you, very much! I have a couple of neighbors who are my usual resources: a machinist, and a school-trained certified diesel mechanic. We should be able to get it done without mayhem (to the tractor or us) thanks to you. We have used a tri-pod with a hoist as a lift before, so we will do a repeat on it. I'll acquire the parts and talk with them, and I'll post on the progress, probably within a couple of weeks. Thanks a heap, Bruce - I really appreciate it.
George

 

[Bruce (VA)]

You're welcome. Glad to help.
75 Tips