More 650 Hydraulic Questions

phil_n · Apr 27, 2015

Well I pulled the pump - it was full of crud and the plungers were stuck but it actually looked in fair shape for wear. It was as if it hasn't had any flow through it for years and just sort-of dried up. I tried blowing air back through the manifold lines - nothing would go through the smaller (high pressure ?) line and only a very little through the larger (return ?) line. Does that sound right? I was expecting basically unrestricted flow through the return line at least.

The following picture is of the top cover: the two missing bolts were in the holes but not tight - it looks like the threads are stripped. What do they do? Are they part of the 3 that you should not remove when you remove the top cover? Could any damage have been done by running it with them loose?

I read about "inspection plates" a lot - is there one for the hydraulic sump? The nearest thing I can think of is the one with the PTO lever on it.

Thanks. phil n

JMOR · Apr 27, 2015

Those are two of 4 that bolt ram cylinder/valve body to the top cover. When missing, I expect that result could be blown gasket.

old · Apr 27, 2015

I could see major problem with those bolts missing. Blown gaskets/o-rings and or broken hold down tabs on the cylinder etc. Either way time to pull the top cover off and have a look see and also see if you can find the missing parts inside since they could be hard on things like the ring and pinion gear

phil_n · Apr 27, 2015

I'll get a gasket set at least before I do. I don't have any hydraulics anyhow so I probably won't be blowing anything up that isn't already blown up.

When I drained the hydraulic oil it was pretty clean looking with no lumps or strange things coming out with it.

souNdguy · Apr 28, 2015

along with the missing cyl bolts... if you can't blow thru the manifold, that should tell you something!

phil_n · Apr 28, 2015

Yeah, but what?

Should I be able to blow easily through both of them normally?

souNdguy · Apr 28, 2015

oil is suposed to flow thru them. do you think that air -shouldn't- be able to flow thru as well?

if you believe in magic.. then maybee...

phil_n · Apr 28, 2015

I thought maybe the pressure line would be normally terminated inside the lift mechanism by whatever the oil pressure was supposed to be acting against - relief valve, piston - whatever, so it would not be expected to pass air without something mechanical happening. I figured the scavenge side should be wide open to the sump.

BTW I do believe in magic. Like sitting here at my computer typing questions and answers magically appear. 8)

Thanks.

souNdguy · Apr 28, 2015

Look at the pump and manifold, then think about where the relief is.. Bottom of the center section. Oil must be able to freely flow thru the intake line in the manifold, and thru the pump, and be pumped out of the pump thru the pressure side of the manifold
. You can't have a mechanical termination of the pressure line at the manifold because you havnt gotten to the relief yet, psi would blow out manifold orings.

Remember, the pump is on the engine, manifold connects I to the trans, pipes in the trans take it to the center section, center has open sump for auction line, and has the relief for the incoming pressure line, from there, oil goes up the center housing to the top cover, from there it can be manipulated further at the blank off plate by adding a scv or diverter, or left alone to feed the cyl and valve assy under the top cover

Sean in PA · Apr 29, 2015

I thought maybe the pressure line would be normally terminated inside the lift mechanism by whatever the oil pressure was supposed to be acting against - relief valve, piston - whatever, so it would not be expected to pass air without something mechanical happening.

This is an open center system. The the fluid should flow from the sump through the pump and then to the control valve and when there is no work being done the fluid then flows back to the sump. It is only when fluid flows into the lift cylinder to lift the 3 point arms and is doing some actual work that the flow should be restricted and the pressure should develop.

JMOR · Apr 29, 2015

A few words are key here: "unrestricted flow", flow freely", etc.
With all assembled, it is not completely "open". You will need the approximately 40 PSI necessary to open the back pressure valve before flow through the high side.

phil_n · Apr 29, 2015

Thank you all for your help. Upon further inspection it seems the pump is needing a serious rebuild. The bearings are shot and the wobble shaft and bearing plate surfaces look like they have been eaten by acid. Can't afford the repairs right now, not to mention who knows how long it'll take to get parts in this alien land of Canada, so for now I'm just going to button it back together minus the innards and bolt it back on the tractor so I can at least use the FEL (separate pump). Also I guess I need at least a gasket set for the top cover before I open that up to take a look. I'll make a 'dummy' gasket to block off the slot where the drive connects to the cam in case engine oil tries to slosh through there.

And, I'm waiting on the FO20 - it's 'in the mail'. :roll:

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