More questions than answers part two

SVcummins

Well-known Member
My system just doesn’t have any capacity it will run for a few seconds full demand but then it starts sucking air and chattering
 
(quoted from post at 12:55:24 02/06/21) My system just doesn t have any capacity it will run for a few seconds full demand but then it starts sucking air and chattering

ASSUMING you are not depressing the clutch at the time almost all the oil the front pump is delivering to a function should be returning to the oil cooler and front pump PLUS transmission pump flow is added to the return flow.

So, in other words, with the transmission pump operating the oil delivered to the front pump will be greater than it can pump at full capacity and there should be an excess return flow to "lube" and NO shortage of oil to the front pump.

Dunno what you've got going on, but it doesn't make sense.

I think you are going to have to buy, borrow rent or steal a FloRater to get to the bottom of this.
 
The front pump should either work or not, running for a few seconds then not sounds like it is starving for fluid.
 
(quoted from post at 14:20:27 02/06/21) The front pump should either work or not, running for a few seconds then not sounds like it is starving for fluid.

The issue is that the front pump cannot draw it's own oil from the sump/rear end of the tractor.

It operates with a "flooded intake", fed from an oil cooler that is fed by function return oil and transmission pump oil, the flow of which should be in excess to what the front pump can pump.

As long as there's a supply of oil in the cooler, above the front pump it should not/cannot "starve" or "cavitate".

For this to work all hydraulic functions have to be working correctly so oil from the front pump returning from a function is filtered and returned to the oil cooler/front pump.

If there is a "high pressure leak to sump" or function return oil is returning "to sump" instead of the cooler the pump intake will no longer be "flooded" and it will cavitate.

SV has previously isolated various functions by blocking of the flow of oil to them without seeming to improve how the front pump functions.

oCLnDbT.jpg


Any excess flow of transmission pump oil combined with function return oil above and beyond the requirements of the front pump exits the upper port of the oil cooler (22) through hose (21) and tube (18) and returns to the transmission area for lube and ultimately returns "to sump".

Even with the front pump at full stroke there should still be a flow of oil out of the cooler (basically the flow rate of the transmission pump at that engine speed minus any 'leaks to sump") which should be pretty minimal in a properly functioning hydraulic system.
 
The one thing we have never gotten to the bottom of is the
fact that the transmission pump will not pass muster it will
pass the no pressure test but will not make the 50 psi the
book calls for ? I’ve had the rockshaft housing off and tractor
running to see if I could see anything but I couldn’t
 
When you had the rockshaft housing off did you inspect the square cover bolted to the underside of the housing ? This cover seals the rockshaft housing forcing return oil through the pipe down to the filter area. There have been cases where one of the bolts on the cover breaks and allows the cover to flex and blow out the packing resulting in a return to sump leak. Symptoms include what you are describing with cavitation after a few seconds of hyd function use. You can sometimes see oil leaking if you look in the hole where you adjust the load sensing arm while someone operates a remote cylinder. New bolts are grade 8 and cover can be re-used if not cracked.
 
4020 synchro early serial . Replaced the transmission pump because the old one wouldn’t pass the test well the new is the exact same
cvphoto74608.jpg
 
That just may be the problem . Also when I run the remote with the jumper hose and a bale on the 3 point hitch the bale slowly lowers
 
I haven't seen all that you have done but with the trans pump test not passing did you pull the manifold where the filter relief valve goes and check the gasket
 
Late to this party, but I have been working on these tractors for 45+ years, I have a couple of questions.

If you sit with the clutch depressed and NO hydraulic functions activated, how many seconds until you can hear the hydraulic pump start to cavitate?

If you remove the hydraulic pump bleed off line at the rear and run the tractor, how much oil is flowing out of the bleed off line?
 
Clutch in I can raise and Lower the 3 point about 3 times . Before this I could fully raise and Lower my farmhand f11 3 times before no oil and those are big long cylinder . Now it won’t hardly raise at all without depressing the clutch
cvphoto74740.jpg
 
Read my original post again, how long until you lose hydraulics WITHOUT using any hydraulic functions with the clutch in. Hold the clutch pedal down for at least 3 minutes or so. I am trying to determine if you have a hi pressure leak to sump with all the system valves in the center (in neutral or the "center" as in "closed center system") or if you have a return oil leak to sump. If there is no or very little of a hi pressure leak to sump it may take a long time for the main pump cavitate.

What has been done to the main hydraulic pump so far? A failed inner crankcase shaft seal can push a lot of oil back to the sump through the bleed off line, although it will usually blow the outer pump shaft seal when it gets real bad. It is pretty simple to disconnect the bleed off line by the brake valve and see how much flow you have with the engine running.
 
I will run a couple tests today . It leaks a bit out of the bleed line but no more than it ever has
 

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