640 hyds looses prime.... and loosening the plug doesn't fix

William Fissell · Nov 23, 2013

Hi,

640 hyds back togetyher, everything great, goes up, stays up, all good.

Come out today to brush hog. No up.

I loosen the pipe plug on the pump ("as usual") and let the air out... hyds come up slowly. Then. not at all.

Loosen pipe plug. nothing. Take pipe plug OUT with engine running. Nothing. Proofmeter shows RPMs. Pump will spit a drop now and then, no more.

Hydraulic fluid levels good by dipstick and overflow plug in diffy case.

I took the hydraulic pump off the and the fluid level in the return line on the manifold was a few inches below the oring.

Suggestions?

thanks in advance

JMOR · Nov 23, 2013

Sucking air or pump no sucky anymore. Try pressurizing at dipstick or hyd fill plug with compressed air. Be sure transmission level is correct, too.

William Fissell · Nov 23, 2013

Pump torn down now so hopefully pump no sucky will
be better very soon.

Irritated that the hyds pump repair kit doesn't
come w manifold seals

Will check tranny level, yes.

how can return line be (apparently) way lower than
level in reservoir... or are my eyes just off?

JMOR · Nov 23, 2013

(quoted from post at 19:47:17 11/23/13) Pump torn down now so hopefully pump no sucky will
be better very soon.

Irritated that the hyds pump repair kit doesn't
come w manifold seals

Will check tranny level, yes.

how can return line be (apparently) way lower than
level in reservoir... or are my eyes just off?

on't know.......seems like the ancient 'water level' to me, except 'oil'.

Anonymous-0 · Nov 23, 2013

Ihave sean the gear on the pump sheer the key and spin on shaft under load. RENE'

William Fissell · Nov 23, 2013

exactly my thouhgt

souNdguy · Nov 23, 2013

return? or pressure line?

William Fissell · Nov 23, 2013

return a few inches low, with dipstick normaal to high

chuck41 · Nov 23, 2013

When you remove that top plug on the pump,you must fill pump w/ hyd fluid-them tighten plug,you
may have to repeat this 2-3 times. Also like
JMOR said to pressurize the dipstick hole till the pump takes ahold. Chuck

souNdguy · Nov 23, 2013

i'm just trying to figure out what you are calling a return line.

I'm assuming the small pressure tube.. not the large suction line.

William Fissell · Nov 23, 2013

Hah! My bad, chris!

small diameter line: full

large diameter line: low

delano nc · Nov 23, 2013

where is the overflow plug on a 640?

Williams Fissell · Nov 23, 2013

My diffy has a pipe plug about 6" up fom bottom on the left rear which I use to Gauge filling.

William Fissell · Nov 24, 2013

Rebuilt pump, reinstalled and re primed. lift goes up and down now, tho not as fast as I'd like

sunbeam · Nov 24, 2013

To prime just just get the front lower than the back. As in a roadside ditch.

Williams Fissell · Nov 24, 2013

Interesting. Will try.

souNdguy · Nov 25, 2013

have you checked for free flow from the sump?

soundguy

souNdguy · Nov 25, 2013

that's for the diffy.. not the hyds.

seperate sumps...

William Fissell · Nov 25, 2013

No, how?

souNdguy · Nov 26, 2013

add air...

if there is a plug inthe suction line.. no pumpy....

640 hyds looses prime.... and loosening the plug doesn't fix

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