770 Hydraulic Problem

MotlyKrug · Jan 1, 2023

Acquired an Oliver 770 that needed a hydraulic pump rebuild to drive the New Idea 503 loader. Note, the loader cylinders have pressure extension and return lines for each. I rebuilt the pump and every cylinder on the loader, put it all back together. As you are sitting on the tractor, the right side hydraulic hook-ups are for the main lift cylinders and are working ok. The problem is the left side rotation cylinders will not work. I know it's building pressure because when i crack the lines at the cylinder they leak presurized air and oil. I'm not sure what I'm doing wrong here but I need some help. Thanks Much!

RCP · Jan 1, 2023

We had a similar problem; it was a hydraulic hose that came apart internally and
plugged the line.

MotlyKrug · Jan 1, 2023

Thanks RCP Ill start replacing hoses and see if that fixes it!

rrlund · Jan 2, 2023

Just pulling this out of my hat. Where the pipes come out of the pump to hook the hoses on, does that still have a kind of rounded
swivel fitting on one of them? Does that have to be turned to a certain position? I think it does for a one way cylinder. Does it
have to be for two way too?

MotlyKrug · Jan 2, 2023

All the cylinders are double action. Here is a picture of the lines with standard swivels on them

MotlyKrug · Jan 2, 2023

No it doesnt have the rounded swivels but Im finding out it does have the flow restrictors inside (I just downloaded a manual). I think I have an issue with the flow restrictor and I will tear into it tomorrow. Thanks so much for the advice!

MotlyKrug · Jan 2, 2023

Update on the hosesI replaced them all and still have an issue. On the bright side, all new hosesthe old hoses were in terrible shape! AlsoI isolated each cylinder & cycled everything.still no dice on the retraction side of either cylinder.

Any other thoughts?

Centerplate · Jan 3, 2023

Motly, I do not see your picture. Please try posting it again. I want to see of the hoses are on the correct ports on the left side of the tractor.
AS a test, could you attach the tilt cylinders to the right hand lever?

MotlyKrug · Jan 7, 2023

(quoted from post at 05:36:17 01/03/23) Motly, I do not see your picture. Please try posting it again. I want to see of the hoses are on the correct ports on the left side of the tractor.
AS a test, could you attach the tilt cylinders to the right hand lever?

Hi Centerplate -

Problem solved, turns out the restrictor valve on the swivel was turned in to tight...in fact it was tightened so tight it took vicegrips to get it lose. I backed it out 4 or 5 turns and it works great now.

Thank you everyone for your advice and input!

770 Hydraulic Problem

MotlyKrug

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RCP

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rrlund

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Centerplate

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