Hydraulics again

[SVcummins]

Ran the test With the clutch in takes about 3 minutes before the pump cavatates

 

[wore out]

(quoted from post at 13:05:34 02/08/21) Ran the test With the clutch in takes about 3 minutes before the pump cavatates

That should pretty much rule out a "high pressure leak to sump".

Now you've got to figure out why "function return oil" (plus the flow from the transmission pump, if your foot is NOT on the clutch pedal) is not getting to the front pump in the required quantity to keep the pump intake "flooded" plus keeping a supply of oil in the oil cooler ahead of pump demand.

 

[David G]

Is that with no loader or 3 pt moving?

 

[SVcummins]

Remember that one guy said about that plate letting the seal
blow out ? Maybe that’s it

 

[SVcummins]

That’s with no demand anywhere on the system

 

[wore out]

(quoted from post at 14:38:57 02/08/21) Remember that one guy said about that plate letting the seal
blow out ? Maybe that s it

"Remember that one guy said about that plate letting the seal
blow out ?"

It would seem that is certainly worth investigating.

In my area 4020's with rockshafts are "rare birds" and I am not personally familiar with that issue, it will be interesting to hear about what you find!

 

[wore out]

I would ASSUME Key# 16 (beneath the hitch valve) is what the other fellow was referring to.

Should be able to remove the plug from the back of the main case and see if any oil is pouring down from there, especially while a helper is cycling a valve to operate a hydraulic function.

Also, the entire rockshaft hydraulics including the return side can be "taken out of play" by capping BOTH the supply and return lines to the rockshaft on the tractor side.

That would prevent transmission pump flow or function return oil from other functions from flowing UP the return line to the rockshaft and "dumping to sump"

 

[WTW]

Just the opposite. It is most likely a high pressure leak to sump is pump runs out of oil when nothing hydraulic is being used. It easily can be
confirmed it is a high pressure leak to sump by simply capping off the pump outlet high pressure line. If pump does not cavitate / run out of oil
the high pressure circuits somewhere in system is leaking to sump. Reconnect high pressure line confirm again by seeing if pump runs out of oil
with pressure line connected. Then find which function leak is in by capping off each function one at a time to determine which one is leaking to
sump. DW

 

[rsq ronnie]

Hello SV; How did you make out on "JDH 15" to adjust valves?

 

[SVcummins]

I have capped the feed line to the rockshaft with no change

 

[SVcummins]

I have capped the brake valve the steering scvs and rockshaft with no change

 

[SVcummins]

I still haven’t found one

 

[WTW]

That's good information. The leak may be in the pump?? If pump is running out of oil with main pump outlet circuits capped off, the first place to look for pump leak is to remove the seal drain line and check for very little to no flow from pump seal?? If seal drain is flowing oil the high pressure seal is out of pump dumping pump oil to sump. Low pressure seal is hiding problem keeping oil from running on ground until it fails. DW

 

[SVcummins]

It has always leaked a fair amount out of the case drain since the pump was new I’ll go pull the line apart and see what it looks like

 

[wore out]

WTW, I don't recall ever disagreeing with you before, but if the front pump doesn't run out of oil for three minutes with the clutch depressed I believe the system passes the "high pressure leak to sump" test.

If I'm wrong pllease explain, I'll listen quietly!

 

[rsq ronnie]

I have one here Ron

 

[wore out]

(quoted from post at 16:30:38 02/08/21) I have capped the feed line to the rockshaft with no change

To rule out a leak to sump from the plate under the rockshaft valve (on the return side) you would need to cap off the tractor side of the return line, as well.

 

[wore out]

(quoted from post at 15:59:48 02/08/21) Just the opposite. It is most likely a high pressure leak to sump is pump runs out of oil when nothing hydraulic is being used. It easily can be
confirmed it is a high pressure leak to sump by simply capping off the pump outlet high pressure line. If pump does not cavitate / run out of oil
the high pressure circuits somewhere in system is leaking to sump. Reconnect high pressure line confirm again by seeing if pump runs out of oil
with pressure line connected. Then find which function leak is in by capping off each function one at a time to determine which one is leaking to
sump. DW

WTW,

After "sleeping on this" I'll modify my comments... What I should have said is that if it takes three minutes of running with the clutch depressed to deplete the supply to the front pump there IS a small "high pressure leak to sump", but I don't believe that is significant enough to completely explain what SV has going on... if I understand correctly he soon runs out of oil available to functions WITH the transmission pump running.

According to SM-2039 a properly functioning transmission pump sends 4 gallons per minute up to the front pump which would be well in excess of what's required to "cover" a leak that takes three minutes to empty the oil cooler, IMHO.

I can't help but think the largest part of his problem is that function return oil and transmission pump oil is winding up in the "sump" rather than getting to the front pump.