801 hydraulics...

Slowly learning about tractors here, so thanks for all the help so far and into the future...
Working on a 1962 851. When I got it the lift would lift but very slow, very weak. I could push the lift arms down with one hand easily. I removed the lift cover and replaced all O-rings and gaskets. Also replaced the lift cylinder O-ring/leather seal. While the lift cover was off I noticed the control valve on the side of the lift cylinder was stuck in place so I was able to free it up and get it moving good again with some lube. I have everything back together now and started the tractor. No lift at all... I pulled the hex plug on the side of the pump and have a lot of pressure/fluid there. I was lost so I called Steiner tractor and they recommended I pull the pipe plug under the seat, over the safety valve to see if I have fluid at the safety valve. I pulled the plug and turned the tractor over for approx. 20-25 seconds with the coil wire off to prevent starting. No fluid at the safety valve.... Steiner's next step is to blow into the dipstick tube with my compressor for about a minute to force fluid through the system. I haven't gotten to do this yet because of... life, but will soon. My question ultimately is, what is actually going on here? Its great to have someone help and tell me what to do next but I really want to understand the why's. Why don't I have fluid at the safety valve now? and if I do have it there what would that indicate. please help me not only fix my issue, but understand my issue. Thanks!
 
I think steiner gave you misleading advice.

If you have oil at the pump, then pressurizing the sump with your blow gun should do nothing. That's a measure to help prime a pump that for whatever reason can't / won't prime on it's own. If you got oil under some ( 40? ) psi pressure .. your pump is most assuredly primed.
 
(quoted from post at 10:52:47 08/31/16) That is where my thought process led me as well. But why then would I not have anything at the safety valve?
hat plug did you actually remove? There is no access to any safety valve from an assembled tractor. Plug on top of accessory plate or plug facing forward toward steering wheel?
 
could be a few things.

1, you might not have stayed at it enough.

don't be shy.. this is trouble shooting.

put that plug on the hyd cover in good finger tight and start that tractor up.. unthread it. if you get an oil geyser.. you are getting oil!

if no oil there, but you have oil at the pump plug, then real quick check to see if the hyds sump is draining and the trans sump is filling.

past that. there are a couple possibilities of why you can get oil at the pump plug and notheing at the top.

1, relief is bad / open, and the oil at the pump is just a small amount of pressure from resistance of pumping it down a tube and back into the sump via a open relief. I call this one rare.. but it is possible. with relief open, you won't get oil up top at the cover. or nothing useable.

2, unload valve is stuck in unload and oil is dumping right to sump.. only pressure you might see is from the backpressure valve that keeps a few psi to keep the unloader system responsive.
 
From what you said and what else I am reading the unloader valve may be the issue. The fact that my control valve was stuck initially would explain why I had minimal lift at first but would hold no pressure... now that the control valve is working properly it sounds as though the unloader valve is stuck, making fluid go around the valve and not actually entering the lift cylinder itself.... am I understanding this correctly?
 
From what you said and what else I am reading the unloader valve may be the issue. The fact that my control valve was stuck initially would explain why I had minimal lift at first but would hold no pressure... now that the control valve is working properly it sounds as though the unloader valve is stuck, making fluid go around the valve and not actually entering the lift cylinder itself.... am I understanding this correctly?
 
Very possible it I essentially stuck, in unload position.

You can make a plug puller with a bolt, piece of steel stock in it and a couple washer stacks, if needed.

If it comes to that I can post pics. They are ones i ripped off from jmor anyway ;)
 
So I got back to the tractor today.... very frustrating. I pulled the pto lever cover and looked inside with the tractor running. No fluid movement at all. Nothing from the lift cylinder in any location... starting to dislike tractors haha
 
It would run down the front of the sump/ from back, non mouth end of the cyl.

Running, you got oil at plug on lift cover?

If no, check trans oil level to see if it is going up
 
No fluid at the plug on top of the accessory plate, and the fluid levels do not appear to change between the trans and hydraulic box... with the tractor running, looking through the pto cover I could notice a rise in the hydraulic fluid just forward of that cover, in the center of that compartment. As if there is pressure coming upward from something there... anything to that?
 
Hmm. Ugh...

Your hyd pressure comes down a tube thru the trans, right side, Then where it joins center section down there is the relief, then oil travels up to the top cover. Under the relief is a access plate.. Sounds about lil where your oil is coming from.. Relief might be popped open.. Thus no oil goes up to hyd cover.

If you are making oil at pump plug, not loosing it in trans, and not getting it at top cover.. Relief is the next thing to look at.
 
Before I buy a relief valve (which seems like the most reasonable next step...) I will pull the hex plug out of the pump again. All I am looking for here is flow (air/bubble free) correct? Because if the system is open there won't be enough pressure to shoot the fluid to the ceiling..?
 
With relief open, it should gurgle. With system open but unloaded, you might get 40psi.. Maybee.

Pull the lower cover before you buy anything.
 
The lower cover being the plate over the relief valve? What will it tell me by pulling it, any obvious signs of failure?
 
Ok I pulled the relief valve. No obvious damage, and the or rings were in good shape. Ugh.
Something I noticed today that may or may not be relevant... with the pipe plug out of the accessory plate and the lift control arm up I have no flow, but with the lift control arm in the down position I have a flow of fluid coming from that hole.... ?
Also I pulled the hex plug from the pump again while running... maybe it's my eyes but there does seem to be a slight pulsation at idle when the fluid is coming out. And with the RPM's revved up the fluid seems to lose the pulsation but is only pushed up about an inch... I assumed with higher RPM's the fluid would have shot higher... maybe I'm just reading too far into this
 
Don't look for pump pressure with hex plug removed.........look for 4 gallons per minute of volume @2000rpm.
 
Ok, so far so good.

Pump I only 2.85 gpm max, some pulse likely means a piston is bad, but many operate like that.

I think we are back to the unloaded stuck in unload.
 
Don't look for pump pressure with hex plug removed.........look for 4 gallons per minute of volume @2000rpm.[/quote]oes it look like you are seeing this volume? If pump is 4gpm, then that is a quart every 4 seconds, and if pump is 2.85gpm, that is a quart every 5.6 seconds. Your description sounds far short of that to me.
 
I will pull it and check it tomorrow. Couldn't hurt. Still baffled though, I really thought I would see fluid dump out of the backside of the cylinder
 
I will guess that you are using ClASSIC VIEW WHERE MY QUESTIONS CONCERNING VOLUME ONLY SEEM TO BE SHOWING UP IN mODERN VIEW.
 
I pulled the plug out completely and
put a bucket underneath and ran the
tractor for a brief period and it
pumped approx a gallon to a gallon and
a half. So I'm thinking the pump isn't
the issue. I have the lift cover off
now to check the unloader valve for
sticking. If not stuck I'm back to lost
again...
 
I pulled the plug out completely and put a bucket underneath and ran the tractor for a brief period and it pumped approx a gallon to a gallon and a half.

Need more detail. How long was the "brief period"?
 
Update! It was the unloader stuck. Words cannot express how happy I am to have it working, thank you both for you help!
So it would seem that with a stuck unloader the fluid recirculates thru the pump and not into the sump.... I would think if it dumped into the sump we would have seen it
 

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