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Ron..... ..Ah yes, the infamous bypass valve chain trick. Its a poormans built-in hydraulic scheme that trys to overcome the lack of a real live hydraulic system on modern tractors. Of course, every time you clutch, the internal hydraulic PTO driven pump stops pumping. It works, but not as well as an external 10 gpm @ 2500 psi pump driven off the engine front pully thru the bottom of the radiator by a long stinger shaft. When you chain the hydraulic lift arm in the DOWN configuration and then try to RAISE them with the hydraulic control, they obviously can't up so the hydraulic pressure bypass valve opens up inside the tractor and diverts about 2.5 gpm @ 1800 psi to the corner test port of the hydraulic pump plate. This test port then is plumbed to some small hydraulic cylinder somewhere it performs some light hydraulic work. Sometimes the pressure valve inside the tractor gives up. Sometimes you can see a swirl in the hydraulic fluid if you take the 6" round plate with the hydraulic dipstick off and carefully look inside. Sometimes you have to drain off about 2-3 gals before you can see. Myself, I say drain it all, probably needs it anyways. Remember, the hydraulic system is 5 gals of Ford/New Holland recommended M2C-134D, 3 drains (differential first), 1 fill up by the tranny shifter. Yeah, you can use the 60 yr old recommendation of 90wt gear oil, if'n you can find it. Hope this helps..... ...Dell
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