300U hydrualics issue-again

hers the deal, my 300 U hydraulic system will sometimes produce a little screaching/groaning sound
with a slight bogging down in engine speed at the same time. This is intermitent. One day it may not happen at all. The next (like yesterday) it's fine for an hour, and then starts acting up every 15-30 seconds. Then it will stop and run fine.
I just took the system completely apart this spring.
Cleaned it all out nice, resivour, screen, lines,
cylinder, valve and controller. I found the screen loaded up with black stuff, and a few red paint chips. The paint chips have come off the inside off the resivour. The black stuff, who knows.
It does not seem to make any difference if I work the cylinder up and down a few times.
So my question is (are):
1- is my pump crapping out I and should replace?
I ran it over the winter with NO hydrofluid and it never screached or moaned or gave trouble. So, I think it's OK.
2- anybody else every have paint chipping off INSIDE the spoolers, res tank etc? and how to fix
3- hydraulic lines rotting out on the inside? anybody have any thoughts on that?

Again, I ran this about 15 hours with the no hydraulic fluid to the pump and it never gave trouble.

Any guidance here is most appreciated
tx
d

Whoa, running a pump with no oil. I hate to run them even a few minutes when they don't prime. Second, what condition is the ORFICE screen in the regulator valve assembly. That is the little jewel that passes the fluid through that tiny orfice to keep regulator piston down on ball keeping it open for low pressure standby. If insufficient fluid flows through the piston will move up, ball seats, system goes on pressure, the increase pressure forces more oil through the orfice and the piston again opens the ball, system goes back on low pressure standby. I usually, (not always) drilled them out a little as the newer orfices were larger. Went from .024 ti .031 but with wear in system I have gone over .040 on some.

Pete is absolutely correct. Good luck, and it is a miracle that it makes pressure at all if run W/no oil. Jim

Hi and thanks again- to be clear-I drained the fluid out in the woods because the pipe under my seat broke, squirting me with hot fluid( last December)and drove it home, 400 yards. Guy at Case IH said NO Problem to run it some with just residual fluid in pump. System NEVER made pressure, but it did not growl/howl screach and bog down the engine. I ran it maybe 4 hours over winter like that to reload wood shed. All ran fine no issues.
Drawbar chained up for use.
I had the system all part a couple weeks ago and all was very clean when reassembled. That screen was clean, all cleaned up nice in parts tanks.
I did find paint chips and black stuff, hence my question about hoses rotting from the inside and paint chips.
We will talk more about drilling it out later.
Is there someone (not dealer) who rebuilds these things?
thanks again

ok its apart- the orifice looks clean and open; that is the "safety valve orifice screen and plug" as indicated in the I&T shop manual. I that the hole to open up?
tx

Yes that is the orfice. If it is marked .024 drill it out to at least .031 as that is what the new ones have been for fifty years, since introduction of 4 & 560 series tractors. If it happens to have a roll pin with ball then it is the intermediate one. Get rid of the roll pin and ball. If you drill too far system will not develop pressure so you have to use wire gauge drill as that is very small. Cut end of screen off, clean out good and roll screen up to seal end. New orfices are over $50 if memory serves me well.

WOW That seems to have worked just fine. Ran for about 3 hours to test, no problems. It does seem to run a little easier with the lift engaged:
i.e. when lift the drawbar, the engine rpm goes up.
Is that normal?
It makes sense it would.

Orifice is marked 2, took it up to 0.031" ;and they are about $80 local, priced a couple months ago.
thanks again
dave

The system maintains a standby pressure of about 60 psi. If when you move the control valve the pressure necessary to move the cylinder is less than 60 psi the pressure in the system will drop and there will be less load on the engine.