300 Utility hydraulics baffling me

Anonymous-0 · Oct 25, 2011

Hello, I have a 300 utility that has just left me at my wits end. Hope someone here has more knowledge, hence good advice for me. My hydraulics sometimes work, and sometimes don't. When they don't work, it's both the fast hitch and remotes that don't work. So it's not just the valve I'm thinking. It has a new hydraulic pump, new filter in hydraulic reservoir beneath seat, new o-rings throughout, and new fluid. I have tried several types of fluid and have blown out the lines with an air compressor to be sure of no obstructions. Also have slightly overfilled reservoir in case dipstick was 'off'. When I put the new filter in, I cleaned the inside of the reservoir so you could almost see your reflection. What else is there? I am completely out of ideas, and hope you may have some fresh ideas for me to try. Sorry for being long winded. Thanks!

Janicholson · Oct 25, 2011

A pin hole or crack in the suction line! Common reality hard to diagnose. Putting pressure into the vent hole under the seat (hole where the vent screws in) can allow oil to escape from the leak, Showing its location. The pilot valve and its tiny screen (see parts diagram caseih.com parts and service) could also have crud in it making it intermittent. Jim

Anonymous-0 · Oct 26, 2011

Thanks for the fresh ideas. Do you think a pinhole would cause all hydraulic functions to cease? When it isn't working nothing even budges or attempts to move, then 10 minutes later it works like the day it rolled off the assembly line.
The pilot valve, is that also referred to as a check valve? I have had the check valve apart and cleaned with new o rings, maybe it's time to try a new check valve?
Thanks for the assistance so far. I know when I get to the bottom of this I'll have a great little tractor on my hands.
Aaron

gurneejoe · Oct 26, 2011

It seems to me like the pressure relief on that circuit is sticking open ocasionally which would allow the oil to just dump back to the reservoir instead of going to the intended implement or hitch.

pete 23 · Oct 26, 2011

The pilot valve Jim referred to is the regulator valve in the block with the four bolt cover and heavy spring under it. It contains the regulator valve, relief valve and orfice screen which feeds the regulator valve. I have seen those orfices drilled out too large and cause your problem. Original was .024 and replacements are .031 so it is a very small hole indeed. Also, if the orfice is loose in the block it can cause your problem. It is a screwdriver slotted orfice with screen on it. The regulator piston has an o-ring on it that can leak and the piston is also spring loaded and that can break internally. It should have considerable resistance to make the button on bottom of piston move against the spring. Then , you might have a loose ball and seat under regulator piston. No one size fits all repair as there are many things that can cause your problem. Leaking o-ring on suction tube to pump also.

300 Utility hydraulics baffling me

Anonymous-0

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Janicholson

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Anonymous-0

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gurneejoe

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pete 23

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