47 8N hydraulics

[Tilman]

My working antique is a 1947 8N and the 3 point lift has some problems. They are1)Only have position control for the top 1/2 of the control lever movement.(2)Jerky lift when cold. (3)Screeching noise on heavy lift-over 600 pounds. (4)Wont consistantly lower when raised with a heavy load. (5) Klicking noise whern lifting a heavy load. I would like to get a good idea what I need parts wise before I tear it down to work on it. Suggestions??

 

[Bruce (VA)]

From your description, you might need just one part: a pump!

Sounds like you have a number of problems some of which you won't be able to diagnose until you get the pump out & on the bench.

The screeching noise is probably the pressure relief valve, so that needs to be replaced. Not lowering is probably a dirty exhaust valve. No position control is likely a cam follower pin & adjustment.

The jerky lift might be a real problem; usually that means one or more of the cylinders isn't pumping.

You will need to pull the lift cover to do the adjustments & replace the cam follower pin and you will need to pull the pump as well. And, you may as well replace the lift piston while you're there.

Before you start, it would be a wise move to get a jig from Zane Sherman 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 need to pull the PTO shaft to get the pump out, so replace the PTO seal.

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.
50 Tips

 

[souNdguy]

Ditto what bruce said.

best case: you need new clean oil after flushing the system, remove and clean the relief, and possibly repalce, and repalce the cam pin. sticky exhaust valve and chambers may heal after this.

worst case... new cam pin, and havd to have cam built up.. new relief.. new oil after cleaning and flush.. no cyl and piston and valve chambers.. plus all the gaskets and gooey stuff needed to button and fill er back up.

It's a 9 hour job or so for a full pump and lift cover R&R if yuo have all the parts on hand... not hard work.. just a bit dirty.. with a lil heavy lifting onthe pump and top cover portion..

soundguy