3 point drops

[ET HUGEN]

Should the 3 point on my 8n be dropping when push the clutch in or should it hold?

 

[Dell (WA)]

ET HUGEN........you do know yer internal hydraulic pump is driven by the tranny PTO shaft don't you? And everytime you clomp yer clodhoppers on the clutch pedal, yer PTO pump stops pumping. When the pump stops pumping, guess what??? yer 3-point hydraulics stop lifting. HOWSOMEVERS: there is a pressure relief valve that is supposed to hold the pressure when you clutch. There are several other causes for 3-point drop including the standpipe and amazingly enuff, yer 3-point hydraulic cylinder.

A good 3-point lift will lift 800lbs and will hold up for 4-hrs. ALWAYS keep yer implements on the ground for SAFETY sake ........Dell

 

[Bruce (VA)]

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.
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[ET HUGEN]

should i start by replacing the safety relief valve then ?

 

[Bruce (VA)]

" should i start by replacing the safety relief valve then ? "

No

You should start by troubleshooting the problem.

 

[old]

First thing to do is pull the right hand inspection cover off the one with the dip stick. Fire it up and if you can have something on the 3 point. Lift it up and look for drips from the cylinder which will be from up high and also look for areas that you see a lot of fluid movement

 

[Tom N MS]

Had two different 9Ns couple of yrs ago that leaked down fast--both had bad safety/pressure relief valves.check this one--after U look inside and rule out upper cylinder piston/rings leak..Some will disagree with this but easiest way to check for fast leakdown caused by bad safety pressure relief valve is----raise the lift with heavy implement--TURN THE TRACTOR OFF--reach in the side and put your finger over the end of the PRV..if it is leaking bad U will actually feel pressure trying to push your finger off of the end of the PRV--slower leak can be cked by using clear 1/2" tubing(about 2 ft) over the end of the PRV--if it is leaking at the PRV you will see oil coming into the tubing..HTH

 

[ET HUGEN]

THANKS !

 

[notjustair]

I did the same dance. I threw a valve in it hoping like everything that was it. It wasn't. I put in a new NAA piston and seals and it works great. Do yourself a favor and order Zane's jig if you have to do the cylinder. He's got great instructions and it makes it a job that only takes a couple of hours tops.

 

[ET HUGEN]

HOW MUCH TIME AND $ WOULD YOU GUESS I AM LOOKING AT ?

 

[notjustair]

I think it was probably $100 or so for the jig and piston and seals. I did my 8n a month ago in a couple of hours. Don't let it scare you.

 

[Anonymous-0]

where did you purchase the parts?

 

[mbramble]

You can buy the parts from this site (top left - Tractor Parts), external_link, or other places. But, before doing any purchasing, please make sure to follow the troubleshooting procedures provided. If you have more questions, just ask and you will get answers. You can spend a lot of un-necessary money just replacing stuff without ever fixing the actual problem if you just start replacing parts.

Zane's jig is definitely a good purchase if you pull off the hydraulics top cover since it lets you make the adjustments just once, instead of repeatedly removing the top cover to tweek them. The top cover is easy to remove and work on but it is HEAVY - I've heard anything from 85-100 lbs -- and cumbersome to move around. I think he was having problems with his web page but his e-mail address is -- [email protected].

 

[Anonymous-0]

I removed the inspection cover and when liftin a heavy blade i noticed alot of fluid coming down from above, so much so that it was pouring out of the 2 o clock bolt hole. I could not see in there very easily. do you use a mirror to inspect in there ?

 

[Bruce (VA)]

Good troubleshooting.

But you do not need a mirror. You've seen all you need to see.

Chances are very, very good that you have a worn lift piston and/or cylinder.

Chances are less that it's a gasket.

You can pull it down & see if it's the lift piston or the cylinder.

Or you can just order all the parts and be done with it.

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.



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. 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 gude 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.

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