1978 John Deere 850 Project

[Rock knocker]

With the tractor at operating speed,,, pump the hydraulic oil into a clean bucket for 5 seconds,,
multiply the measured amount by 12,,, that will be your flow per minute.

That is so fraught with logistical issues as to be impossible and useless.
1) How do you drain the entire pumps capacity while the engine is running full RPM. Do you suggest adding on a valve to divert the entirety of the flow? Make an error while you switch and the tubing could be subject to almost unlimited pressure with no safety relief, and you are right there in the middle of it with your fingers, hands and face.
2) How do you measure 5 seconds? Get things a second off and your results are seriously flawed. They are flawed even if only half a second off.

 

[Rock knocker]

This Fram filter is the one I changed. Does this tractor also have some sort of drain in the sump? Is that large bolt on the bottom the drain plug?

Like JD110 said, that bolt is the drain. If it won't budge, you can pull the cap which will drain the system and let you clean or replace the suction screen.

 

[beenthere]

Knocker

I took the suggestion as removing the end of a hyd. hose connected to a control valve. Aim that end into a container and the actuate the control valve. Count off 5 seconds and close the control valve. Measure the volume pumped.

May not be to the nearest tenth, but the measured amount would not be less than the gpm output. Might point out where the problem lies. And it might not.

Would not "drain the entire pumps capacity", but just measure flow volume in 5 seconds. It is how I took the suggestion, when no flow meter was available and an estimate for trouble shooting was needed.

 

[Rock knocker]

Knocker

I took the suggestion as removing the end of a hyd. hose connected to a control valve. Aim that end into a container and the actuate the control valve. Count off 5 seconds and close the control valve. Measure the volume pumped.

May not be to the nearest tenth, but the measured amount would not be less than the gpm output. Might point out where the problem lies. And it might not.

Would not "drain the entire pumps capacity", but just measure flow volume in 5 seconds. It is how I took the suggestion, when no flow meter was available and an estimate for trouble shooting was needed.

And what kind of results do you have? How about the portion that may be diverted to the PS or the rock shaft? It is so prone to substantial measuring errors it is a waste of time to assume that you will get any substansive answer from those shenanigans

 

[CADplans]

That is so fraught with logistical issues as to be impossible and useless.
1) How do you drain the entire pumps capacity while the engine is running full RPM. Do you suggest adding on a valve to divert the entirety of the flow? Make an error while you switch and the tubing could be subject to almost unlimited pressure with no safety relief, and you are right there in the middle of it with your fingers, hands and face.
2) How do you measure 5 seconds? Get things a second off and your results are seriously flawed. They are flawed even if only half a second off.

Well,, it was a better answer than "Gee,, I do not know,,,"
The hydraulics of that tractor are so simple, the flow is so low, and ,,, if you try something,,,
it is WAY better than "Gee,, I do not know,,,"

 

[wct097]

After the filter change the hydraulics seem stronger. I was able to lift the front of the tractor off the ground with the FEL, which suggests to me that the flow may not be as bad as I thought. My current plan is to remove the cap and clean the suction screen as suggested, drain and replace the fluid, and change the filter again. Hopefully that'll keep me going for another 6 months or so until we get moved and I can take the time to remove the SCV to see if I can repair it.

 

[elkaybmx]

You may also want to check the hydraulic hose just in front of your remote filter (the fram). It is suction side and tends to collapse, especially when the hydro fluid is cold. I put a brand new one on mine and it failed in a year or so. Next one I put on a added a wire similar to what is in a radiator hose. Also not sure if I saw in this thread were you cleaned the metal filter, which is in the base of the transmission. Your picture on previous page shows where it is located. It is the circular tube with a plate with 2 bolts holding cover on end.

 

[wct097]

Since my last post, I've used the tractor a good bit, changed the filter on the hydraulics a couple of times, but found it to be lacking in the warm weather and unusable in the cold.

I took the loader control valve off of my tractor yesterday. It had numerous issues including not returning to center/neutral, leaking from the top of the spools, and letting the stick over-travel (figured that one out). Additionally, the entire system became unusable in the cold. Yesterday I started it up and it took about 15 minutes to raise the bucket. Once warmed, it still couldn't hold the bucket up. I checked the fluid level and found the fluid to be showing signs of water (milky yellow color). At that point, I decided to park it and remove the control valve and change the fluid.

Once removed, one of the spools pulled out of the valve completely. I'm assuming this isn't normal... So my questions are:

Is it worth trying to rebuild? Am I likely to find that the spools are worn due to water intrusion, and thus not usable? Should I try it myself or take it somewhere? Is that just wasting time and money at this point? Should I just replace it with an aftermarket unit?

If I do replace it with an aftermarket unit, would I expect it to mount up the same or (more likely, IMO), would I be having to customize a mounting solution? When going aftermarket, do you just buy flex hoses to replace the hard lines? Do I have to get them custom made, or can I find pre-fab options at tractor supply or northern tool or something?

Here is the factory mounting:

 

[CADplans]

I would bet there is close to ZERO chance that valve could be replaced with an aftermarket without EXTENSIVE modifications,,,

I would be at Blue Ridge Diesel in Salem VA on Monday morning,,
if they could not rebuild the valve, they could direct you to the right place to do the rebuild,,,

Lynchburg must have a good hydraulics shop?? :thumbsup:

 

[Fallon]

The spools need to fit perfectly in the bores of the valve bodies. It's extremely precision machining & metal on metal tolerances. There are no seals to replace or rebuild, only the metal on metal surfaces keeping the hydraulic fluid from leaking.