555 no hydraulics

[JimFord555]

1979 555 lost all hydraulics suddenly

I can slightly tilt the loader and that s about it.

Did some research and checked:
-hoe main relieve valve
-loader system relieve valve
-tank had proper level of hydraulic fluid then I drained it undid the outlet and it has no filter screen and nothing was impending it
-filter was newish but had a small amount of metal bits in it (probably from when I pushed down on a rigger with the hoe and stripped the nut inside the ram connecting it to the plunger. That s fixed now)
-removed the pump and opened it up and it looks great to me
(Pump was being turned properly by its driveshaft and fluid was flowing and returning to tank when I looked into the filler hole while running)

I m guessing I need to go deeper into the relieve valves but thought I d check and see if anyone has any other ideas

Here is the YouTube of what I did https://youtu.be/ryhJFQJctWM

 

[Andy Wickiser]

Since you made visual inspections of all
of the suspected problem areas it's
probably time to buy, improvise, beg,
borrow or steal a hydraulic tester. Then
start by verifying that the pump can make
pressure when flow is restricted. Once
that is established move on to testing the
system relief valves. Hopefully you have
a service manual to follow the various
procedures. Sorry for the non-definitive
answer.

 

[JimFord555]

Sounds good. I have a manual and a few heavy duty mechanic friends that can help with the test equipment. This is a very frustrating problem