8N lift not working correct

Hello, I need some help form all you 8N experts before I tear into my tractor. Recently bought this 8N and the lift is acting up. WIth no load it lifts as normal
but when you put weight on it, it pulsates and lifts really slow. I already replaced the piston and seal in the lift cylinder. That helped, it wouldn't lift under
load at all with the old one. To me, it feels like only one or two of the pistons in the pump aren't pumping under load. Assuming I'll have to pull the pump but
what problem should I look for?

Thanks for all you advice
Charlie

HiYa Charlie-
Did you perform the Hydraulic System Leak Down Test First? Your issues are consistent with a worn hydraulic system, a typical problem on these old N's. Was the color of the oil a milky-white or muddy brownish? Oil should be a semi-clear honey like color. White indicates oil is contaminated with water and there can be a few reasons why. The worse case scenario is the pump base is cracked. As you know, the N-TRACTOR hydraulic lift uses the same sump as the transmission. When water gets into the sump for whatever reason, might be the tractor has set outside for many years, a typical cause, the sump will freeze when weather gets below 32 DEG F. When the operator fires up his machine and tries to run system out of the gate without first warming up the engine and hydraulic system, the water in sump has turned to ice and can damage the pump thus causing the aluminum base to crack. The Leak Down Test is simple, fast, and done thru the side inspection covers. Oil level and oil color should be the first things to visually look at. You've already realized your 3-PT Lift has a problem. You were half-way there by replacing the piston and wiper, but you don't say if you also replaced the entire cylinder with a new one. The leak test would verify that the cylinder was probably old and worn and needed replacing and is the usual suspect when this happens. The FORD hydraulic system is one of the most neglected systems mainly because owners use the old if it ain't broke philosophy. It is not a difficult task, time consuming mostly, as it requires pulling the top cover off and dropping the pump to do the job right. You want to do it right the first time so you don't have to pull the top cover off twice or more. The OEM N hydraulic piston used three steel rings on the piston for the wiper and seals, similar to your engine pistons. This would cause the cylinder walls to gouge and wear out of round when the oil was low and dirty. The NAA design was a better resolution with the piston that had an rubber O-RING seal and a leather backup wiper. The NAA-533-B Piston and NAA-473-A Backup Washer/Wiper also work on the 9N/2N/8N systems as well. Did you replace the 8N-638 Safety Relief Valve too? Often guys want a quick-fix band-aid when lift issues arise and try this first as you don't need to pull the pump or top cover to do. You can get to the valve thru the side inspection covers and only need an 11/16 Stub Length Open End Wrench to do. However, I advise to just plan on getting into the whole system to do right, but if you want to try the valve first, its your call. Finally, know that the 9N/2N system is different than the 8N system. Pulling the top cover must be done on both but the cylinders are bolted to the bottom of the cover and must be left attached when the cover is pulled off. If you undo the 4 cylinder bolts, before the cover is removed, you are in for a disaster. The 9N/2N Cylinder Assembly uses a wishbone linkage that must be disconnected before the top cover is pulled off. The 8N uses POSITION CONTROL as well as DRAFT CONTROL. There is a Control Rod that must be handled carefully when pulling the top cover off and on so it doesnt get bent or damaged, then inserted into the pump base at reassembly. Use your 8N Operators Manual and the I&T FO-4 Manual to R&R the system before doing any wrenching. I wrote a document years ago on the 8N Hydraulic System, rebuilding on a budget. If you want a copy, my email is open. Don't buy any new parts until you decide what you are going to do. A complete pump rebuild kit will run about $350 not including a new cylinder, piston and wiper, Safety Relief Valve, and gasket kit for cylinder. If pump is not cracked, a basic rebuild can be done for a lot less. Used pumps pop up on ebay often and can be around that same price range, rebuilt and not rebuilt as well. Caveat Emptor. My email is open.

Tim Daley(MI)

Thanks for all the good information. Yes I did replace with a new cylinder and piston (oring style). Once I did this, it doesn't lead down any more. Was pretty fast before the replacement. I guess what I'm wanting is an opinion of whats going on in the pump to have all the pulsation and only lifting on some of the pistons and not the others under load. I'm thinking a crack in the pump that lets the fluid leak under load but still lifts with no load. But I'm not real familiar with the ford pumps. Most of my experience is with gear pumps on JD and IH.

(quoted from post at 19:42:14 08/29/22) Thanks for all the good information. Yes I did replace with a new cylinder and piston (oring style). Once I did this, it doesn't lead down any more. Was pretty fast before the replacement. I guess what I'm wanting is an opinion of whats going on in the pump to have all the pulsation and only lifting on some of the pistons and not the others under load. I'm thinking a crack in the pump that lets the fluid leak under load but still lifts with no load. But I'm not real familiar with the ford pumps. Most of my experience is with gear pumps on JD and IH.

Click to expand...

Could be /probably is as simple as leaking valves.

TOH