Hydraulic 3-point will not lift, but holds when lifted..

[pknotlost]

So my 3-point hitch will not raise the implement much- maybe 4 inches; with nothing on it it raises just fine. But with the rake, it will hardly raise it; if two people lift the implement, then it goes up and will stay up. So it will hold it once it's up. I'm leaning on something to do with a weak pump, not so much as leaking by or leaking down..... I am opening the inspection port next step, any suggestions on what I'm looking for?

It’s a 1950 8N

 

[Jim L WA]

It would help to know what tractor you have. The 9N and 2N's have a little different system than the 8N. You could have a weak pump or you might have a control valve issue or a safety valve issue. When you remove the inspection cover, look for leaks from above while trying to lift the implement. With the tractor OFF, reach down in the rear and feel around to make sure the linkage is attached. Then feel if the lift control valve (8N) is moving all the way, The 9 or 2N has only one valve.

 

[Kondoge]

whelp mine has the same problem actually, wont lift weight well but holds well when lifted, mines a 9N 1940 but same issue none the less, your lift cylinder is likely leaking under load as is the case for mine, or the safety valve is blown.

to test for a leak of the lift cylinder take the inspection port cover off and throw the lift lever In raise with the PTO engage (wont lift if you don't but you probably know that), if you see a waterfall of oil it is leaking,

could also be other things such as a worn out pump, blown pump gaskets.

mine 9n is an interesting case the lift cylinder leaks under load (I can see the waterfall of oil) but not while sitting as it will hold the implement up for quite a while I know mines the lift cylinder, hopefully my case may be able to help you figure your 8N out.

Best of luck.

 

[pknotlost]

I took the inspection port off and there’s no waterfall coming from the top. There’s nothing that I can see be behaving wrong. I’m not sure how to check and test to see how much pressure it’s developing. I have gauges, but I’m not sure if there’s a port I can hook it up to to test it anywhere. Is there a port on the 8N that I can connect a gauge to to test how much pressure it’s generating ? How do I check if the relief valve is holding?

 

[Jim L WA]

This is interesting. Just yesterday I took my 2N out to hook up a pine needle rake after it sat for over a year (long story). What do you know, it's doing the same thing as yours. Very slow lift but will hold. I haven't gotten into it yet, won't be till next week, but I really think it's the control valve sticking in the bore because of the feel of the control lever.
You can check your pressure from the plug down at the right hand front corner of the sump. You need a 0-2000 psi gauge. There should be 1500-1700 psi at 1500 RPM.

 

[HarryVanderpool]

Could be sticky valves. When it attempts to lift is it jerky?

 

[soaked]

Is this the washered down position control lever, (draft mode) 1950 8n?

If it lifts to full up position with no weight, the pumps lever is moving to the full up position, and the intake valve is opening while exhaust valve is closed.

Are the clamp bolts on the top of each side chamber holding the inlet/outlet valve caps tight and not leaking?
More info is more better
Worn pumps may lift when cold, then struggle when warmed up.

 

[pknotlost]

Could be sticky valves. When it attempts to lift is it jerky?

No not jerky very smooth

 

[Kondoge]

thats odd... hmm something ain't right that's the only thing I can say for sure. what hydrotransdiffy oil you using? Please don't say strawberry flavoured ATF...

 

[pknotlost]

Is this the washered down position control lever, (draft mode) 1950 8n?

If it lifts to full up position with no weight, the pumps lever is moving to the full up position, and the intake valve is opening while exhaust valve is closed.

Are the clamp bolts on the top of each side chamber holding the inlet/outlet valve caps tight and not leaking?
More info is more better
Worn pumps may lift when cold, then struggle when warmed up.

I’ll have to figure out what the clamp bolts are. I did not see any leaking by. I am using 90 w mineral oil from Tractor Supply

 

[Hobo,NC]

A reminder….

Override the lift linkage by manually operating it. Wink Wink

If his lift holds the #1 obvious conclusion would be a lift linkage/adjustment ware issue. Override it and get that out of the way Life will be good.